How diverse are dogs in their traits other than appearance?

How diverse are dogs in their traits other than appearance?

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I've asked this question about dogs not so long ago, and the short answer was - dogs are the most diverse looking species of mammals because they got a small number of genes that have a big impact on appearance.

I would like to ask a follow up question- differences in appearance are easy to notice, and I would like to learn about other traits that might be genetically based.

Are there other major differences between dog breeds, like longevity, cognitive performance, friendliness, etc? Or are all dogs more or less the same in traits other than appearance?

Are there plots of traits like these among different dog breeds that identify outliers?

Dogs are highly diverse in their patterns of copy number variation (variation in the number of copies of different genes). This has been shown to be probably related to the diversity in morphology. It would thus presumably also affect other traits such as those that you list, and it seems to at least have been shown for disease susceptibility. Interestingly, wolves have less copy number variation on average than dogs (citation).

A Dog's Eye View of Morphological Diversity

Copyright: © 2010 Liza Gross. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Competing interests: The author has declared that no competing interests exist.

The history of genetic discovery offers a lesson in inspired choices. Mendel pried the principles of inheritance from the seeds, pods, and flowers of pea plants. Morgan linked trait inheritance to specific chromosomes after the unexpected appearance of a white-eyed fly among the red-eyed multitudes. McClintock showed that genes could change position on a chromosome by charting the idiosyncrasies of every leaf and kernel of her beloved maize plants.

And now Elaine Ostrander, who admits a sense of “awe” and “marvel” at her pet organism, the domestic dog, has found that some complex traits may not have such a complex genetic basis after all. Working with longtime collaborators Carlos Bustamante and Robert Wayne, Ostrander and her colleagues report that complex traits like body size and coat color may fall under the control of surprisingly few genes.

Early on, Ostrander recognized the dog's potential to undercover the genetic basis of complex traits. Morgan's white-eyed flies arose from a single-gene mutation, but most traits spring from more complex genetic interactions. Complex (or quantitative) traits are controlled by more than one gene, in combination with environmental factors, and vary by degree, with snout, for example, ranging from recessed to elongated.

Pure-bred dogs, with their storied history of intensive breeding for humans' prodigious preferences, offer geneticists a unique opportunity to link variations at a given spot in the genome (the genotype) with the physical expression (phenotype) of complex traits. From the puny pug's snub nose to the regal collie's prominent snout, the squat corgi's stubby legs to the sleek saluki's willowy limbs, the hairless chihuahua's nervous reserve to the dreadlocked komondor's fearless courage, no other land mammal approaches the dog's phenotypic diversity. Breeders maintain these archetypes by selecting for nearly every facet of a dog's being, leaving breeds with restricted gene pools and prone to genetic disease.

Still, such clear divisions among breeds help geneticists match genes with traits. Researchers have recently linked numerous gene variants and so-called quantitative trait loci (QTL)—regions of DNA associated with a trait—to several classic traits in dog breeds, including leg length, coat color, and skeletal size. It's possible that this diversity results from several QTLs with weak effects or from just a few QTLs with large effects.

To explore these possibilities and track the signs of human selection in the dog genome, Ostrander, Bustamante, and their colleagues developed a map of canine genetic diversity. Dogs, like humans, have two copies of every gene. The copies may have identical sequences (called homozygous) or different sequences (heterozygous). Using DNA from registered breeds and wild canids (915 dogs from 80 breeds, plus 83 canids, including wolves, jackals, coyotes, and feral African “village” dogs), the authors determined the sequence of over 120,000 spots in the genome likely to harbor single nucleotide polymorphisms (SNPs, pronounced “snips”)—that is, they determined which of the four DNA bases (A, C, T, and G) occupy these sites. Such single-base variations, where one dog may have an A and another a T, promise to reveal the genetic roots of morphology, behavior, and disease.

Using statistics, scientists can identify a SNP at one spot in the genome that occurs with another SNP at an adjacent location more often than one would expect by chance. The SNPs may or may not occur within a gene. The nonrandom association of SNPs (called linkage disequilibrium) and blocks of DNA can help researchers map genome regions that encode heritable traits and also provide clues to an organism's evolutionary history.

One would expect that sequences inherited from the gray wolf, the dog's evolutionary forerunner, would show up as shorter blocks of shared DNA (broken up by the random mixing of DNA from both parents over generations). Likewise, the genetic imprint of inbreeding, the lot of all official dog breeds, might be long stretches of identical sequences (referred to as “runs of homozygosity,” or ROHs).

Not surprisingly, individuals within breeds share long stretches of identical sequence (ROHs) while individuals across different breeds—and African village dogs and wolves, which mate randomly—do not. Interestingly, different breeds share many more linked loci than wolves do, supporting the notion that dogs went through a genetic bottleneck during domestication. Even so, village dogs harbor more genetic diversity than the gray wolf, perhaps because they managed to keep their populations large enough to avoid inbreeding, unlike the relentlessly persecuted wolf.

The finding that dogs from different breeds do not share large chunks of DNA, the authors explain, suggests that different breeds share few sequences inherited from their ancestors. But, they reasoned, sequences shared among breeds with similar features may well represent the genetic resources from which humans fashioned the remarkably diverse expression of these traits.

Indeed, the authors linked several shared sequences to genetic variants affecting classic morphological traits, including fur length and texture, coat color, stubby legs, snout length, and body weight. When breeders selected for variations of these traits, they unwittingly targeted certain regions of the genome, but which ones?

To find out, the authors looked for correlations between the frequency of specific genetic variations and specific phenotypes—including body size, ear type, and skull, dental, and skeletal dimensions—across 80 breeds. For body size, where dogs take the prize for biggest range among terrestrial mammals, six genomic regions stood out, including areas with genes known to influence body size. For ear type, another breed-defining trait, just one region emerged as the likely source for everything from the pharaoh hound's outsized, erect ears to the basset's low-hanging, floppy lugs. The modern mutation in this area is nearly ubiquitous in floppy-eared dogs and the region shows greatly reduced sequence diversity, both indicators of strong selection.

In nearly all the traits studied, the authors report, just a few high-impact QTLs accounted for the phenotypic variations across breeds. Interestingly, genome-wide association studies in humans suggest just the opposite: that most complex human traits fall under the control of hundreds of genes of small effect.

The patterns of linked genetic regions, with so few controlling trait diversity, indicate that breed dogs (and village dogs) went though a bottleneck at domestication, followed by another bottleneck, resulting from strong selection as humans aggressively bred dogs for whatever trait struck their fancy.

Aside from proving the dog's value as a genetic model, this study offers researchers a treasure trove of genetic data to pair genes with traits, illuminate the dog's evolution from wolf to companion, and secure its place as the geneticist's new best friend.

Boyko AR, Quignon P, Li L, Schoenebeck J, Degenhardt JD, et al. (2010) A Simple Genetic Architecture Underlies Morphological Variation in Dogs. doi:10.1371/journal/pbio.1000451

Part 1: Defining Terms


Species is a Latin word meaning &ldquokind&rdquo or &ldquoappearance.&rdquo No doubt, we learn to distinguish among different types of plants and animals&mdashbetween cats and dogs, for instance&mdashby their appearance. Today biologists use many aspects other than an organism&rsquos appearance to characterize species: body functions, biochemistry, behavior, and genetic make-up. As such there are many ways to define what a species is. The most common species concept is the &ldquobiological species concept.&rdquo

Lab Question


Taxonomy is the identification and classification of species. The taxonomic system developed by Linnaeus in the eighteenth century is still used today. It has two main features. First, it assigned to each species a two-part Latin name. The first word of the name is the genus to which the species belongs. The second part of the name, the specific epithet, refers to one species within the genus. For example, humans are Homo sapiens while the black rat isRattus rattus and the Norwegian rat isRattus norvegicus. Notice each species has its own unique name, but the two rat species have a similar genus name. This means that the two rat species are in the same genus and suggests that they are more closely related to each other than either of them are to humans which are in a different genus.

The second component of the taxonomic system developed by Linnaeus was adopting a filing system for grouping species into a hierarchy of increasingly general categories. Taxonomists place related genera in the same family, groups of related families into orders, groups of related orders into classes, classes into phyla (phylum, singular), phyla into kingdoms, and kingdoms into domains.

Today we are going to focus on three of the four kingdoms in the domain Eukarya (organisms with nuclei): kingdom Plantae, kingdom Animalia, and kingdom Fungi.

Bulldogs Are Dangerously Unhealthy, But There May Not Be Enough Diversity in Their Genes to Save Them

Uga, the beloved canine mascot of the University of Georgia’s sports teams, wouldn’t be much on the field. With his squashed, baby-like face and stout, low-slung torso, he looks more likely to take a nap than make a tackle. Yet it is because of these very features—not in spite of them—that the bulldog has won hearts on both sides of the Atlantic, rising to the heights of university mascot and even proud icon of the U.S. Marine Corps.

Related Content

And it is because of the bulldog’s legions of admirers—not in spite of them—that the breed is now in trouble. Decades of breeding have accentuated the traits that make up the dog's distinctive and wildly popular look, but compromised its health in the process. Now, the first comprehensive genetic assessment suggests that the bulldog no longer has the genetic diversity left for breeders to raise enough healthy animals to improve its overall outlook.

“They've lost so much genetic diversity over the past decades,” says Niels Pedersen, professor emeritus of medicine and epidemiology at the University of California at Davis School of Veterinary Medicine and lead author of the new assessment. “It's a breed that's really kind of bred itself into a genetic corner.”

The study, published Thursday in the open access journal Canine Genetics and Epidemiology, represents the first broad-based effort to assess genetic diversity among English bulldogs using DNA analysis. Pedersen and colleagues tested 102 registered English bulldogs used for breeding, 87 from the United States and 15 from overseas. They compared that group with a second subset of 37 English bulldogs that had been brought to the university's Veterinary Clinical Services for various health problems.

For bully-lovers, the results are harrowing: Researchers found that little wiggle room remains in the bulldogs' limited genes for breeders to rebuild healthy phenotypes from within the existing breed. Introducing new genes from outside the purebred bulldog line could be a boon to the animals' health. But because the resulting dogs are no longer pedigreed and don't look exactly like today's standard, diehard bulldog breeders aren't likely to start that process anytime soon.

Boasting both looks and personality, the bulldog has long been among the most popular dog breeds in the U.S. and UK. The American Kennel Club describes them as “equable and kind, resolute and courageous." As Pedersen puts it: "The bulldog's saving grace is that people absolutely love them and are willing to overlook all their health problems. They're an ideal pet, relatively small but not that small, they don't bark a lot, they aren't that active, and they are really placid and they have a beautiful disposition.” 

But his research suggests that all that love might not be enough to save them. In fact, love itself is the problem.

The original "Handsome Dan," circa 1889. (Yale University Manuscripts & Archives Digital Images Database / Wikimedia Commons)

It's well known that bulldogs suffer from a variety of physical ailments that make them particularly unhealthy—and that many are the unfortunate byproducts of breeding to the extremes of the same physical features that win them prizes and acclaim. As a result, the bulldog's lifespan is relatively short, with most living on average a mere 8 years according to one recent study by the National Institutes of Health.

The bulldog's list of ailments is long. First their thick, low-slung bodies, broad shoulders and narrow hips make bulldogs prone to hip dysplasia and make it difficult for them to get around. Short snouts and compressed skulls cause most to have serious breathing difficulties, which not only increases their risk of respiratory-related death but makes it tough to keep cool. Wrinkly skin can also make bulldogs more prone to eye and ear problems. As if that weren’t enough, the dogs are plagued by allergic reactions and autoimmune disorders exacerbated by inbreeding.

Perhaps the most telling example of how dramatically human breeders have manipulated the bulldog is this: The breed is now largely unable to procreate naturally (even more so than the giant panda, which notoriously requires “panda porn” to be enticed to do the deed in captivity). Bulldogs are often too short and stocky to mate, and their heads as infants are too big for a natural birth from the dog's narrow pelvis. So the breed survives thanks to artificial insemination and cesarian section births, which have become the norm.

How did the sturdy bulldog, symbol of the British Empire, end up in such a bind? First, you have to understand that today's bulldog is the product of hundreds of years of selective breeding. As recently as the mid-19th century it looked quite different. The bulldog’s ancestors were fighters, bred for bull-baiting before the English banned the sport in 1835. But those taller, leaner, less-wrinkled and far more athletic bulldogs didn’t make great house pets, and so were largely unwanted.

Soon, a handful of breeders who loved the dogs began to reinvent them through selective breeding. By the second half of the 19th century the bulldog had a new look—and a new popularity that criss-crossed the Atlantic ocean. The AKC recognized the modern breed of bulldog in 1886, and the bulldog was chosen to represent such august institutions as Yale University, which appointed the bully "Handsome Dan" as its icon in 1889. But the seeds of the modern bulldog’s genetic demise were sown from the start, Pedersen says. 

A very small number of founding dogs—just 68, by Pedersen’s estimates—began the breed. All purebred bulldogs today have descended from those dogs and their progeny. Later, humans created subsequent “bottlenecks” that even further reduced the gene pool of this small group. “Those probably involved a popular sire that everybody loved,” Pedersen explains. “He may have been a show winner, and so everybody then subsequently bred his line.”

In recent decades, the dog’s popularity has spawned inbreeding and rapidly altered the shape and style of its body—as one can see in the various versions of Uga, the University of Georgia mascot. But inbreeding isn’t the primary problem, says Pedersen. It's that such breeding was done to create the distinctive physical attributes that make a bulldog look like a bulldog. Those aesthetic “improvements”—dramatic changes to head shape and size, skeleton, and skin—come with a heavy cost.

“If you look at standard poodles, they're almost as inbred as bulldogs but they are far more healthy because their inbreeding wasn't directed towards drastically changing their appearance,” Pedersen says. “The standard poodle doesn't look too much different than the ancestral village dogs, that are still in the Middle East and other parts of the world."

Many breeders simply deny that the bulldog has any unusual problems. “It is a myth that the Bulldog is inherently unhealthy by virtue of its conformation,” declares the Bulldog Club of America's official statement on the health of the breed. Yet a Journal of Veterinary Internal Medicine study that investigated causes of death for more than 70,000 dogs between 1984 and 2004, found that bulldogs were the second most likely breed to die of congenital disease. (Newfoundlands were most likely.)

Breeders often blame health ills on unscrupulous, puppy mill-type breeders who breed sick and otherwise unsuitable dogs indiscriminately. It’s true that the odds of getting a healthier individual bulldog are far better when buyers deal with credible breeders who screen for health issues in advance. But when it comes to the health of the breed as a whole, the genes tell a different story, says Pedersen.

Puppy mill breeders can run down the genetics of a popular breed in a hurry, but that doesn't appear to apply where the bulldog is concerned. “When we analyzed the dogs who came into the clinic for health problems, who tended to be more common or pet store type bulldogs, they were genetically identical to the registered and well-bred dogs,” he says. “The mills aren't producing dogs that are much differently genetically as far as we could see than the ones being bred properly.”

Understanding genetic diversity is crucial to managing the future of any breed, says Aimée Llewellyn-Zaidi, head of health and research at the Kennel Club (Britain's counterpart to the AKC). Her organization has participated in genetic research, including providing canine subjects for a 2015 genetic study published in Canine Genetics and Epidemiology that estimated the rate of loss of genetic diversity within pedigreed dogs. That study found that bulldogs might enjoy some modest replenishment of genetic diversity through the use of imported animals, which could be an avenue to improve bulldog genetics.

“It would be very interesting to use genomic tools to investigate the bulldog breed on a global level, as it is well-established that breeds that have developed in isolation over time can be utilized to improve over-all genetic diversity and selection for positive characteristics, on a global level,” says Llewellyn-Zaidi, who was not involved in the research.

Some breeders are already taking steps to improve the lovable dog's lot. In 2009, the Kennel Club altered the regulations for bulldogs to discourage breeding for the purpose of exaggerating features like short muzzles or loose skin that humans find desirable but have detrimental impacts on dog health. That means leaner bulldogs, and less wrinkly ones so that eyes and noses are not obscured. Others are creating non-pedigreed, mixed bulldog breeds like the Olde English Bulldogge and the Continental Bulldog, which look more like throwbacks to the bulldog's more athletic ancestors.

If such hybrid breeds catch on, the bulldog's future might look a bit more like its past—and certainly a lot brighter. But that will only happen if more breeders decide to embrace something a bit different from the dogs they now know and love. 

BioEd Online


Students explore phenotypic differences in hair types found in the coats of different dog breeds, as they begin to learn about complex traits. Based on information provided, students also predict the genotypes of different dog breeds.

This activity is from the Complex Traits guide for teachers. Lessons are designed for use with students in grades 6&ndash8, but they also may be easily adjusted for use with other grade levels as appropriate.

Teacher Background

Most characteristics, such as height, body shape and disease susceptibility, in living organisms are controlled by more than one gene. Coat type in dogs is an example. Variations in three genes determine the patterns of hair length, curl and presence of &ldquofurnishing&rdquo (beard and bushy eyebrows, combined with wiry hair) that are observable in about 95% of all dog breeds. In this activity, students will categorize the coat phenotypes of eight different dog breeds, and then will connect the phenotypes to possible genotypes.

The dog breeds that are included in this activity are the Bassett Hound, Bichon Frise, Border Terrier, English Cocker Spaniel, Golden Retriever, Havanese, Irish Water Spaniel, and Kerry Blue Terrier. These breeds display the complete range and combinations of coat types: long vs. short hair, curly vs. straight hair, and presence or absence of furnishings. The ancestors of modern dogs all had coats with short, straight hair without furnishings. The other characteristics have arisen because of mutations in genes related to hair growth and development. Mutations are changes in the DNA sequence, usually as a result of mistakes when DNA is copied. If the mutation is present in the egg or sperm cell of a parent, it is passed onto the offspring. In dogs, selective breeding has consolidated and increased the frequency of many mutations that affect appearance or behavior.

Three different genes regulate hair type in dogs. Hair length (L), as described previously, can be long or short. The ancestral condition in dogs is short hair. Long-haired dogs have inherited a mutation involving the substitution of a single nucleotide in the gene responsible for terminating hair growth. Dogs with one or two copies of the mutation have long hair. Thus, dogs with the genotype &ldquoLl&rdquo and &ldquoLL&rdquo have short hair. Dogs with the genotype &ldquoll&rdquo have long hair.

Curl (C) is governed by a change in one of the genes responsible for a structural protein in hair (keratin). The mutation again involves the substitution of a single nucleotide&mdashthis time, a T (thymine) is substituted for a C (cytosine). The substitution is believed to affect folding of the completed protein, leading to curled or wavy hair. Dogs with straight hair have two copies of the straight form of the gene (cc) dogs with wavy hair have one copy of the straight form of the gene and one copy of the curly form (Cc) dogs with curly hair are homozygous for the curly mutation (CC).

Wiry hair is an interesting characteristic in dogs. Dogs that possess hair that is coarse and bristly like wire, always also have a beard (longer hair on the chin and muzzle and bushy eyebrows. Dog experts refer to the additional facial hair features as &ldquofurnishings.&rdquo All of these physical changes are due to the same mutation in a single gene. The gene is responsible for producing a signaling protein important for keratin development and initiation of hair growth. Importantly, in this case, one mutation in a single gene leads to multiple changes in the phenotype. The Irish terrier, shown at right, provides a good example of furnishing and wiry coat. The mutation leading to wiry hair and furnishings consists of the insertion of 167 base pairs within the signaling protein gene called RSPO2. This means that extra DNA was added into the existing sequence that comprised the gene. The extra section of DNA appears to change the levels and actions of the proteins produced by the gene.

Only one copy of the &ldquofurnishings&rdquo (F) mutation is necessary for the characteristic to be present. A dog with the genotype &ldquoff&rdquo will not have furnishings. However, a dog with Ff or FF will present the furnishings phenotype.

When only one copy of an allele is necessary for a trait to be present, inheritance of the trait is described as &ldquodominant.&rdquo Furnishings is an example of a dominant trait. Dogs with only one copy of the furnishings allele (genotype of Ff) will have wiry hair and a bearded face. Conversely, absence of furnishings is a recessive trait, because two copies of the allele (ff) are necessary for furnishings to be absent.

Objectives and Standards

Materials and Setup

Complex Traits slide set (slides 27&ndash41), available at

Computer and projector, or interactive whiteboard

Set of eight Dog Breed cards copied onto cardstock (see p. 25&ndash26 one set per group)

Copy of &ldquoGenetics of Dog Coats&rdquo (p. 27, one per student)

Copy of &ldquoConfirmed Hair Genotypes&rdquo to be distributed after students have completed Part 2, item 6 (one per student, p. 28)

Procedure and Extensions

Part 1: Hair phenotypes

Remind students about the activity, &ldquoGenotypes and Phenotypes.&rdquo Ask, Is short or long hair the only distinguishing characteristic of dog&rsquos coats? Students might mention curly vs. straight hair or coat color. Explain, Coat color and patterns of color, for example, are governed by interactions among many different genes. Show students Slide 27, with two different coat patterns. Mention, for example, that several different genes can be responsible for something that appears simple, such as a black coat.

Show Slide 28 and tell students that they will be investigating hair length and texture in eight different dog breeds. Give each group of students one set of Dog Breed cards. Direct the members of each group to discuss the different kinds of fur or hair that can be observed on the dogs. Use the term &ldquophenotype&rdquo when referring to the different observable features of hair.

Next, direct the groups to sort the eight cards into different categories of fur or hair. They should not use color as a criterion for sorting.

After the groups have sorted their cards, allow each group to present or describe the different coat categories they used.

Part 2: Hair genotypes

Remind students about what they already have learned about the gene mutation that determines whether a dog has long or short hair. (If necessary, revisit Slide 24.) Discuss the other characteristics that contribute to hair type in dogs. Show Slide 29 and explain that three genes govern the hair type in most breeds of dogs. The gene for hair length is one of the three genes. Curl is affected by a gene that codes for one of the structural proteins in hair. Like the gene for hair length, a single point mutation is responsible for the curly allele. In this case, however, one inherited copy of the mutation (Cc) causes soft, wavy hair and two copies (CC) cause soft, curly hair. A dog must have two copies of the original (&ldquoancestral&rdquo) version of the allele (cc) to have straight hair.

Display Slide 30 showing a photo of an Irish terrier with furnishing and wiry hair. Ask if any of the students have a dog with similar facial and coat hair. Mention that the eyebrows and beard are called &ldquofurnishings.&rdquo Tell students that the coat hair is stiff like wire. In the case of the gene for furnishing, extra DNA (167 base pairs) has been inserted into the original gene. The protein produced by the gene is involved in switching on other genes, and the additional DNA changes how that protein regulates hair growth. Mention that this is an example of how a single gene can have effects in many different parts of the body.

Give each group of students the sheet entitled &ldquoGenetics of Dog Coats&rdquo (Slide 31). Tell students that they will decide on the phenotype and genotype of each dog, based on what they have learned about the genetics of hair type.

Display Slide 32. Point out that photos of a dog&rsquos coat may be misleading because of breed standards in dog competitions.

Project Slide 33 showing the Bichon Frise by itself. Tell students, Let&rsquos figure out what the genotype of the dog must be, based on the traits that we have observed and recorded.

Since the Bichon has long hair, which combination of alleles is possible? [&ldquoll&rdquo is the only possible genotype.]

We determined that the hair is curly. What genotypes are possible? [Since the Bichon is clearly &ldquocurly,&rdquo and not wavy or straight, the genotype is CC].

Since the dog has furnishing, what are the possible genotypes? [It is not possible to know if the individual pictured is homozygous, FF, or heterozygous, Ff. However, since the trait appears consistently within members of the breed, it is reasonable to assume that most individuals of this breed are homozygous for the furnishings allele, FF].

Let each group work through the remaining dog breeds. (Slides 33&ndash40 contain enlarged images all eight dogs for use as needed.) Tell students to determine the phenotypes of all the dogs, before proceeding to the genotypes. If you have Internet access in your classroom, students may want to access additional photographs of the different breeds to look for characteristics, such as furnishings.

Have the groups report on their conclusions regarding the genotype and phenotypes of each breed, by asking each group to present the findings for a different breed. Or, have each group submit a written explanation of the decisions they made regarding each breed.

Distribute the student sheet, &ldquoConfirmed Hair Genotypes,&rdquo which summarizes typical genotypes for each breed (Slide 41) for a discussion with the class. Students may notice that in most cases, the breeds are homozygous for dominant traits. Based on phenotype, it is not possible to know if an individual has a single or both alleles for a trait that shows a dominant pattern of inheritance. However, because dog breeds have been selected over generations to &ldquobreed true,&rdquo most of the variant alleles have been eliminated over time. In other words, dogs with undesirable characteristics themselves (or whose offspring had undesirable characteristics) were not bred to produce additional offspring.


The origin of the domestic dog (Canis lupus familiaris or Canis familiaris) is not clear. Whole-genome sequencing indicates that the dog, the gray wolf and the extinct Taymyr wolf diverged around the same time 27,000–40,000 years ago. [3] How dogs became domesticated is not clear, however the two main hypotheses are self-domestication or human domestication. There exists evidence of human-canine behavioral coevolution.

Dog intelligence is the ability of the dog to perceive information and retain it as knowledge in order to solve problems. Dogs have been shown to learn by inference. A study with Rico showed that he knew the labels of over 200 different items. He inferred the names of novel items by exclusion learning and correctly retrieved those novel items immediately. He also retained this ability four weeks after the initial exposure. Dogs have advanced memory skills. A study documented the learning and memory capabilities of a border collie, "Chaser", who had learned the names and could associate by verbal command over 1,000 words. Dogs are able to read and react appropriately to human body language such as gesturing and pointing, and to understand human voice commands. After undergoing training to solve a simple manipulation task, dogs that are faced with an insolvable version of the same problem look at the human, while socialized wolves do not. Dogs demonstrate a theory of mind by engaging in deception. [4] [5]

The dog's senses include vision, hearing, sense of smell, taste, touch, proprioception, and sensitivity to the earth's magnetic field.

Dog communication is about how dogs "speak" to each other, how they understand messages that humans send to them, and how humans can translate the ideas that dogs are trying to transmit. [6] : xii These communication behaviors include eye gaze, facial expression, vocalization, body posture (including movements of bodies and limbs) and gustatory communication (scents, pheromones and taste). Humans communicate with dogs by using vocalization, hand signals, and body posture. Dogs can also learn to understand communication of emotions with humans by reading human facial expressions. [7]

Two studies have indicated that dog behavior varied with their size, body weight and skull size. [8] [9]

Play Edit

Dog-dog Edit

Play between dogs usually involves several behaviors that are often seen in aggressive encounters, for example, nipping, biting and growling. [10] It is therefore important for the dogs to place these behaviors in the context of play, rather than aggression. Dogs signal their intent to play with a range of behaviors including a "play-bow", "face-paw," "open-mouthed play face" and postures inviting the other dog to chase the initiator. Similar signals are given throughout the play to maintain the context of the potentially aggressive activities. [11]

From a young age, dogs engage in play with one another. Dog play is made up primarily of mock fights. It is believed that this behavior, which is most common in puppies, is training for important behaviors later in life. Play between puppies is not necessarily a 50:50 symmetry of dominant and submissive roles between the individuals dogs who engage in greater rates of dominant behaviors (e.g. chasing, forcing partners down) at later ages also initiate play at higher rates. This could imply that winning during play becomes more important as puppies mature. [12]

Emotional contagion is linked to facial mimicry in humans and primates. Facial mimicry is an automatic response that occurs in less than 1 second in which one person involuntary mimics another person's facial expressions, forming empathy. It has also been found in dogs at play, and play sessions lasted longer when there were facial mimicry signals from one dog to another. [13]

Dog-human Edit

The motivation for a dog to play with another dog is distinct from that of a dog playing with a human. Dogs walked together with opportunities to play with one another, play with their owners with the same frequency as dogs being walked alone. Dogs in households with two or more dogs play more often with their owners than dogs in households with a single dog, indicating the motivation to play with other dogs does not substitute for the motivation to play with humans. [14]

It is a common misconception that winning and losing games such as "tug-of-war" and "rough-and-tumble" can influence a dog's dominance relationship with humans. Rather, the way in which dogs play indicates their temperament and relationship with their owner. Dogs that play rough-and-tumble are more amenable and show lower separation anxiety than dogs which play other types of games, and dogs playing tug-of-war and "fetch" are more confident. Dogs which start the majority of games are less amenable and more likely to be aggressive. [15]

Playing with humans can affect the cortisol levels of dogs. In one study, the cortisol responses of police dogs and border guard dogs was assessed after playing with their handlers. The cortisol concentrations of the police dogs increased, whereas the border guard dogs' hormone levels decreased. The researchers noted that during the play sessions, police officers were disciplining their dogs, whereas the border guards were truly playing with them, i.e. this included bonding and affectionate behaviors. They commented that several studies have shown that behaviors associated with control, authority or aggression increase cortisol, whereas play and affiliation behavior decrease cortisol levels. [16]

Empathy Edit

In 2012, a study found that dogs oriented toward their owner or a stranger more often when the person was pretending to cry than when they were talking or humming. When the stranger pretended to cry, rather than approaching their usual source of comfort, their owner, dogs sniffed, nuzzled and licked the stranger instead. The dogs' pattern of response was behaviorally consistent with an expression of empathic concern. [17]

A study found a third of dogs suffered from anxiety when separated from others. [18]

Personalities Edit

The term personality has been applied to human research, whereas the term temperament has been mostly used for animal research. [19] However, both terms have been used interchangeably in the literature, or purely to distinguish humans from animals and avoid anthropomorphism. [20] Personality can be defined as “a set of behaviors that are consistent over context and time”. [21] Studies of dogs' personalities have tried to identify the presence of broad personality traits that are stable and consistent over time. [20] [21] [22] [23]

There are different approaches to assess dog personality:

  • Ratings of individual dogs: either a caretaker or a dog expert who is familiar with the dog is asked to answer a questionnaire, for instance the Canine Behavioral Assessment and Research Questionnaire, [24] concerning how often the dog shows certain types of behavior.
  • Tests: the dog is submitted to a set of tests and its reactions are evaluated on a behavioral scale. For instance, the dog is presented to a familiar and then an unfamiliar person in order to measure sociability or aggression. [25]
  • Observational test: The dog’s behavior is evaluated in a selected but not controlled environment. An observer focuses on the dog’s reactions to naturally occurring stimuli. For example, a walk through the supermarket can allow the observer to see the dog in various types of conditions (crowded, noisy…) [26]

Several potential personality traits have been identified in dogs, for instance "Playfulness", "Curiosity/Fearlessness, "Chase-proneness", "Sociability and Aggressiveness" and "Shyness–Boldness". [27] [28] A meta-analysis of 51 published peer reviewed articles identified seven dimensions of canine personality: [20]

  1. Reactivity (approach or avoidance of new objects, increased activity in novel situations)
  2. Fearfulness (shaking, avoiding novel situations)
  3. Activity
  4. Sociability (initiating friendly interactions with people and other dogs)
  5. Responsiveness to training (working with people, learning quickly)
  6. Submissiveness
  7. Aggression

Dog breed plays an important role in the dog's personality dimensions, [29] [30] while the effects of age and sex have not been clearly determined. [21] The personality models can be used for a range of tasks, including guide and working dog selection, finding appropriate families to re-home shelter dogs, or selecting breeding stock. [31] [32] [33]

Leadership, dominance and social groups Edit

Dominance is a descriptive term for the relationship between pairs of individuals. Among ethologists, dominance has been defined as "an attribute of the pattern of repeated, antagonistic interactions between two individuals, characterized by a consistent outcome in favor of the same dyad member and a default yielding response of its opponent rather than escalation. The status of the consistent winner is dominant and that of the loser subordinate." [34] Another definition is that a dominant animal has "priority of access to resources". [34] Dominance is a relative attribute, not absolute there is no reason to assume that a high-ranking individual in one group would also become high ranking if moved to another. Nor is there any good evidence that "dominance" is a lifelong character trait. Competitive behavior characterized by confident (e.g. growl, inhibited bite, stand over, stare at, chase, bark at) and submissive (e.g. crouch, avoid, displacement lick/yawn, run away) patterns exchanged. [35]

One test to ascertain in which group the dominant dog was used the following criteria: When a stranger comes to the house, which dog starts to bark first or if they start to bark together, which dog barks more or longer? Which dog licks more often the other dog's mouth? If the dogs get food at the same time and at the same spot, which dog starts to eat first or eats the other dog's food? If the dogs start to fight, which dog usually wins? [36]

Domestic dogs appear to pay little attention to relative size, despite the large weight differences between the largest and smallest individuals for example, size was not a predictor of the outcome of encounters between dogs meeting while being exercised by their owners nor was size correlated with neutered male dogs. [37] Therefore, many dogs do not appear to pay much attention to the actual fighting ability of their opponent, presumably allowing differences in motivation (how much the dog values the resource) and perceived motivation (what the behavior of the other dog signifies about the likelihood that it will escalate) to play a much greater role. [35]

Two dogs that are contesting possession of a highly valued resource for the first time, if one is in a state of emotional arousal, in pain if reactivity is influenced by recent endocrine changes, or motivational states such as hunger, then the outcome of the interaction may be different than if none of these factors were present. Equally, the threshold at which aggression is shown may be influenced by a range of medical factors, or, in some cases, precipitated entirely by pathological disorders. Hence, the contextual and physiological factors present when two dogs first encounter each other may profoundly influence the long-term nature of the relationship between those dogs. The complexity of the factors involved in this type of learning means that dogs may develop different "expectations" about the likely response of another individual for each resource in a range of different situations. Puppies learn early not to challenge an older dog and this respect stays with them into adulthood. When adult animals meet for the first time, they have no expectations of the behavior of the other: they will both, therefore, be initially anxious and vigilant in this encounter (characterized by the tense body posture and sudden movements typically seen when two dogs first meet), until they start to be able to predict the responses of the other individual. The outcome of these early adult–adult interactions will be influenced by the specific factors present at the time of the initial encounters. As well as contextual and physiological factors, the previous experiences of each member of the dyad of other dogs will also influence their behavior. [35]

Scent Edit

Dogs have an olfactory sense 40 times more sensitive than a human's and they commence their lives operating almost exclusively on smell and touch. [6] : 247 The special scents that dogs use for communication are called pheromones. Different hormones are secreted when a dog is angry, fearful or confident, and some chemical signatures identify the sex and age of the dog, and if a female is in the estrus cycle, pregnant or recently given birth. Many of the pheromone chemicals can be found dissolved in a dog's urine, and sniffing where another dog has urinated gives the dog a great deal of information about that dog. [6] : 250 Male dogs prefer to mark vertical surfaces and having the scent higher allows the air to carry it farther. The height of the marking tells other dogs about the size of the dog, as among canines size is an important factor in dominance. [6] : 251

Dogs (and wolves) mark their territories with urine and their stools. [38] The anal gland of canines give a particular signature to fecal deposits and identifies the marker as well as the place where the dung is left. Dogs are very particular about these landmarks, and engage in what is to humans a meaningless and complex ritual before defecating. Most dogs start with a careful bout of sniffing of a location, perhaps to erect an exact line or boundary between their territory and another dog's territory. This behavior may also involve a small degree of elevation, such as a rock or fallen branch, to aid scent dispersal. Scratching the ground after defecating is a visual sign pointing to the scent marking. The freshness of the scent gives visitors some idea of the current status of a piece of territory and if it is used frequently. Regions under dispute, or used by different animals at different times, may lead to marking battles with every scent marked-over by a new competitor. [6] : 252–4

Feral dogs Edit

Feral dogs are those dogs living in a wild state with no food and shelter intentionally provided by humans, and showing a continuous and strong avoidance of direct human contacts. [39] In the developing world pet dogs are uncommon, but feral, village or community dogs are plentiful around humans. [40] The distinction between feral, stray, and free ranging dogs is sometimes a matter of degree, and a dog may shift its status throughout its life. In some unlikely but observed cases, a feral dog that was not born wild but living with a feral group can become behavior-modified to a domestic dog with an owner. A dog can become a stray when it escapes human control, by abandonment or being born to a stray mother. A stray dog can become feral when forced out of the human environment or when co-opted or socially accepted by a nearby feral group. Feralization occurs through the development of the human avoidance response. [39]

Feral dogs are not reproductively self-sustaining, suffer from high rates of juvenile mortality, and depend indirectly on humans for their food, their space, and the supply of co-optable individuals. [39]

Other behavior Edit

Dogs have a general behavioral trait of strongly preferring novelty ("neophillia") compared to familiarity. [41] The average sleep time of a dog in captivity in a 24-hour period is 10.1 hours. [42]

Estrous cycle and mating Edit

Although puppies do not have the urge to procreate, males sometimes engage in sexual play in the form of mounting. [43] In some puppies, this behavior occurs as early as 3 or 4 weeks-of-age. [44]

Dogs reach sexual maturity and can reproduce during their first year, in contrast to wolves at two years-of-age. Female dogs have their first estrus ("heat") at 6 to 12 months-of-age smaller dogs tend to come into heat earlier whereas larger dogs take longer to mature.

Female dogs have an estrous cycle that is nonseasonal and monestrus, i.e. there is only one estrus per estrous cycle. The interval between one estrus and another is, on average, seven months, however, this may range between 4 and 12 months. This interestrous period is not influenced by the photoperiod or pregnancy. The average duration of estrus is 9 days with spontaneous ovulation usually about 3 days after the onset of estrus. [45]

For several days before estrus, a phase called proestrus, the female dog may show greater interest in male dogs and "flirt" with them (proceptive behavior). There is progressive vulval swelling and some bleeding. If males try to mount a female dog during proestrus, she may avoid mating by sitting down or turning round and growling or snapping.

Estrous behavior in the female dog is usually indicated by her standing still with the tail held up, or to the side of the perineum, when the male sniffs the vulva and attempts to mount. This tail position is sometimes called “flagging”. The female dog may also turn, presenting the vulva to the male. [45]

The male dog mounts the female and is able to achieve intromission with a non-erect penis, which contains a bone called the os penis. The dog's penis enlarges inside the vagina, thereby preventing its withdrawal this is sometimes known as the "tie" or "copulatory lock". The male dog rapidly thrust into the female for 1–2 minutes then dismounts with the erect penis still inside the vagina, and turns to stand rear-end to rear-end with the female dog for up to 30 to 40 minutes the penis is twisted 180 degrees in a lateral plane. During this time, prostatic fluid is ejaculated. [45]

The female dog can bear another litter within 8 months of the previous one. Dogs are polygamous in contrast to wolves that are generally monogamous. Therefore, dogs have no pair bonding and the protection of a single mate, but rather have multiple mates in a year. The consequence is that wolves put a lot of energy into producing a few pups in contrast to dogs that maximize the production of pups. This higher pup production rate enables dogs to maintain or even increase their population with a lower pup survival rate than wolves, and allows dogs a greater capacity than wolves to grow their population after a population crash or when entering a new habitat. It is proposed that these differences are an alternative breeding strategy, one adapted to a life of scavenging instead of hunting. [46]

Parenting and early life Edit

All of the wild members of the genus Canis display complex coordinated parental behaviors. Wolf pups are cared for primarily by their mother for the first 3 months of their life when she remains in the den with them while they rely on her milk for sustenance and her presence for protection. The father brings her food. Once they leave the den and can chew, the parents and pups from previous years regurgitate food for them. Wolf pups become independent by 5 to 8 months, although they often stay with their parents for years. In contrast, dog pups are cared for by the mother and rely on her for milk and protection but she gets no help from the father nor other dogs. Once pups are weaned around 10 weeks they are independent and receive no further maternal care. [46]

There are many different types of behavioural issues that a dog can exhibit, including growling, snapping, barking, and invading a human's personal space. A survey of 203 dog owners in Melbourne, Australia, found that the main behaviour problems reported by owners were overexcitement (63%) and jumping up on people (56%). [47] Some problems are related to attachment while others are neurological, as seen below.

Separation anxiety Edit

When dogs are separated from humans, usually the owner, they often display behaviors which can be broken into the following four categories: exploratory behaviour, object play, destructive behaviour, and vocalization, and they are related to the canine's level of arousal. [48] These behaviours may manifest as destructiveness, fecal or urinary elimination, hypersalivation or vocalization among other things. Dogs from single-owner homes are approximately 2.5 times more likely to have separation anxiety compared to dogs from multiple-owner homes. Furthermore, sexually intact dogs are only one third as likely to have separation anxiety as neutered dogs. The sex of dogs and whether there is another pet in the home do not have an effect on separation anxiety. [49] It has been estimated that at least 14% of dogs examined at typical veterinary practices in the United States have shown signs of separation anxiety. Dogs that have been diagnosed with profound separation anxiety can be left alone for no more than minutes before they begin to panic and exhibit the behaviors associated with separation anxiety. Separation problems have been found to be linked to the dog's dependency on its owner, not because of disobedience. [48] In the absence of treatment, affected dogs are often relinquished to a humane society or shelter, abandoned, or euthanized. [50]

Resource guarding Edit

Resource guarding is exhibited by many canines, and is one of the most commonly reported behaviour issues to canine professionals. [51] It is seen when a dog uses specific behaviour patterns so that they can control access to an item, and the patterns are flexible when people are around. [52] If a canine places value on some resource (i.e. food, toys, etc.) they may attempt to guard it from other animals as well as people, which leads to behavioural problems if not treated. The guarding can show in many different ways from rapid ingestion of food to using the body to shield items. It manifests as aggressive behaviour including, but not limited to, growling, barking, or snapping. Some dogs will also resource guard their owners and can become aggressive if the behaviour is allowed to continue. Owners must learn to interpret their dog's body language in order to try to judge the dog's reaction, as visual signals are used (i.e. changes in body posture, facial expression, etc.) to communicate feeling and response. [51] These behaviours are commonly seen in shelter animals, most likely due to insecurities caused by a poor environment. Resource guarding is a concern since it can lead to aggression, but research has found that aggression over guarding can be contained by teaching the dog to drop the item they are guarding. [52]

Jealousy Edit

Canines are one of a number of non-human animals that can express jealousy towards other animals or animal-like objects. [53] This emotion may feed into other behavioural problems, manifest as attention-seeking behaviour, withdrawing from social activity, or aggression towards their owner or another animal or person.

Noise anxiety Edit

Canines often fear, and exhibit stress responses to, loud noises. Noise-related anxieties in dogs may be triggered by fireworks, thunderstorms, gunshots, and even loud or sharp bird noises. Associated stimuli may also come to trigger the symptoms of the phobia or anxiety, such as a change in barometric pressure being associated with a thunderstorm, thus causing an anticipatory anxiety.

Tail chasing Edit

Tail chasing can be classified as a stereotypy. It falls under obsessive compulsive disorder, which is a neuropsychiatric disorder that can present in dogs as canine compulsive disorder. [54] In one clinical study on this potential behavioral problem, 18 tail-chasing terriers were given clomipramine orally at a dosage of 1 to 2 mg/kg (0.5 to 0.9 mg/lb) of body weight, every 12 hours. Three of the dogs required treatment at a slightly higher dosage range to control tail chasing, however, after 1 to 12 weeks of treatment, 9 of 12 dogs were reported to have a 75% or greater reduction in tail chasing. [55] Personality can also play a factor in tail chasing. Dogs who chase their tails have been found to be more shy than those who do not, and some dogs also show a lower level of response during tail chasing bouts. [54]

Comparisons made within the wolf-like canids allow the identification of those behaviors that may have been inherited from common ancestry and those that may have been the result of domestication or other relatively recent environmental changes. [39] Studies of free-ranging African Basenjis and New Guinea Singing Dogs indicate that their behavioral and ecological traits were the result of environmental selection pressures or selective breeding choices and not the result of artificial selection imposed by humans. [56]

Early aggression Edit

Dog pups show unrestrained fighting with their siblings from 2 weeks of age, with injury avoided only due to their undeveloped jaw muscles. This fighting gives way to play-chasing with the development of running skills at 4–5 weeks. Wolf pups possess more-developed jaw muscles from 2 weeks of age, when they first show signs of play-fighting with their siblings. Serious fighting occurs during 4–6 weeks of age. [57] Compared to wolf and dog pups, golden jackal pups develop aggression at the age of 4–6 weeks when play-fighting frequently escalates into uninhibited biting intended to harm. This aggression ceases by 10–12 weeks when a hierarchy has formed. [58]

Tameness Edit

Unlike other domestic species which were primarily selected for production-related traits, dogs were initially selected for their behaviors. [59] [60] In 2016, a study found that there were only 11 fixed genes that showed variation between wolves and dogs. These gene variations were unlikely to have been the result of natural evolution, and indicate selection on both morphology and behavior during dog domestication. These genes have been shown to affect the catecholamine synthesis pathway, with the majority of the genes affecting the fight-or-flight response [60] [61] (i.e. selection for tameness), and emotional processing. [60] Dogs generally show reduced fear and aggression compared to wolves. [60] [62] Some of these genes have been associated with aggression in some dog breeds, indicating their importance in both the initial domestication and then later in breed formation. [60]

Social structure Edit

Among canids, packs are the social units that hunt, rear young and protect a communal territory as a stable group and their members are usually related. [63] Members of the feral dog group are usually not related. Feral dog groups are composed of a stable 2–6 members compared to the 2–15 member wolf pack whose size fluctuates with the availability of prey and reaches a maximum in winter time. The feral dog group consists of monogamous breeding pairs compared to the one breeding pair of the wolf pack. Agonistic behavior does not extend to the individual level and does not support a higher social structure compared to the ritualized agonistic behavior of the wolf pack that upholds its social structure. Feral pups have a very high mortality rate that adds little to the group size, with studies showing that adults are usually killed through accidents with humans, therefore other dogs need to be co-opted from villages to maintain stable group size. [39]

Socialization Edit

The critical period for socialization begins with walking and exploring the environment. Dog and wolf pups both develop the ability to see, hear and smell at 4 weeks of age. Dogs begin to explore the world around them at 4 weeks of age with these senses available to them, while wolves begin to explore at 2 weeks of age when they have the sense of smell but are functionally blind and deaf. The consequences of this is that more things are novel and frightening to wolf pups. The critical period for socialization closes with the avoidance of novelty, when the animal runs away from - rather than approaching and exploring - novel objects. For dogs this develops between 4 and 8 weeks of age. Wolves reach the end of the critical period after 6 weeks, after which it is not possible to socialize a wolf. [46]

Dog puppies require as little as 90 minutes of contact with humans during their critical period of socialization to form a social attachment. This will not create a highly social pet but a dog that will solicit human attention. [64] Wolves require 24 hours contact a day starting before 3 weeks of age. To create a socialized wolf the pups are removed from the den at 10 days of age, kept in constant human contact until they are 4 weeks old when they begin to bite their sleeping human companions, then spend only their waking hours in the presence of humans. This socialization process continues until age 4 months, when the pups can join other captive wolves but will require daily human contact to remain socialized. Despite this intensive socialization process, a well-socialized wolf will behave differently to a well-socialized dog and will display species-typical hunting and reproductive behaviors, only closer to humans than a wild wolf. These wolves do not generalize their socialization to all humans in the same manner as a socialized dog and they remain more fearful of novelty compared to socialized dogs. [65]

In 1982, a study to observe the differences between dogs and wolves raised in similar conditions took place. The dog puppies preferred larger amounts of sleep at the beginning of their lives, while the wolf puppies were much more active. The dog puppies also preferred the company of humans, rather than their canine foster mother, though the wolf puppies were the exact opposite, spending more time with their foster mother. The dogs also showed a greater interest in the food given to them and paid little attention to their surroundings, while the wolf puppies found their surroundings to be much more intriguing than their food or food bowl. The wolf puppies were observed taking part in antagonistic play at a younger age, while the dog puppies did not display dominant/submissive roles until they were much older. The wolf puppies were rarely seen as being aggressive to each other or towards the other canines. On the other hand, the dog puppies were much more aggressive to each other and other canines, often seen full-on attacking their foster mother or one another. [66]

A 2005 study comparing dog and wolf pups concluded that extensively socialised dogs as well as unsocialised dog pups showed greater attachment to a human owner than wolf pups did, even if the wolf was socialised. The study concluded that dogs may have evolved a capacity for attachment to humans functionally analogous to that human infants display. [67]

Cognition Edit

Despite claims that dogs show more human-like social cognition than wolves, [68] [69] [70] several recent studies have demonstrated that if wolves are properly socialized to humans and have the opportunity to interact with humans regularly, then they too can succeed on some human-guided cognitive tasks, [71] [72] [73] [74] [75] in some cases out-performing dogs at an individual level. [76] Similar to dogs, wolves can also follow more complex point types made with body parts other than the human arm and hand (e.g. elbow, knee, foot). [75] Both dogs and wolves have the cognitive capacity for prosocial behavior toward humans however it is not guaranteed. For canids to perform well on traditional human-guided tasks (e.g. following the human point) both relevant lifetime experiences with humans - including socialization to humans during the critical period for social development - and opportunities to associate human body parts with certain outcomes (such as food being provided by human hands, a human throwing or kicking a ball, etc.) are required. [77]

After undergoing training to solve a simple manipulation task, dogs that are faced with an insoluble version of the same problem look at the human, while socialized wolves do not. [70]

Reproduction Edit

Dogs reach sexual maturity and can reproduce during their first year in contrast to a wolf at two years. The female dog can bear another litter within 8 months of the last one. The canid genus is influenced by the photoperiod and generally reproduces in the springtime. [39] Domestic dogs are not reliant on seasonality for reproduction in contrast to the wolf, coyote, Australian dingo and African basenji that may have only one, seasonal, estrus each year. [45] Feral dogs are influenced by the photoperiod with around half of the breeding females mating in the springtime, which is thought to indicate an ancestral reproductive trait not overcome by domestication, [39] as can be inferred from wolves [78] and Cape hunting dogs. [79]

Domestic dogs are polygamous in contrast to wolves that are generally monogamous. Therefore, domestic dogs have no pair bonding and the protection of a single mate, but rather have multiple mates in a year. There is no paternal care in dogs as opposed to wolves where all pack members assist the mother with the pups. The consequence is that wolves put a lot of energy into producing a few pups in contrast to dogs that maximize the production of pups. This higher pup production rate enables dogs to maintain or even increase their population with a lower pup survival rate than wolves, and allows dogs a greater capacity than wolves to grow their population after a population crash or when entering a new habitat. It is proposed that these differences are an alternative breeding strategy adapted to a life of scavenging instead of hunting. [46] In contrast to domestic dogs, feral dogs are monogamous. Domestic dogs tend to have a litter size of 10, wolves 3, and feral dogs 5–8. Feral pups have a very high mortality rate with only 5% surviving at the age of one year, and sometimes the pups are left unattended making them vulnerable to predators. [39] Domestic dogs stand alone among all canids for a total lack of paternal care. [80]

Dogs differ from wolves and most other large canid species as they generally do not regurgitate food for their young, nor the young of other dogs in the same territory. [81] However, this difference was not observed in all domestic dogs. Regurgitating of food by the females for the young, as well as care for the young by the males, has been observed in domestic dogs, dingos and in feral or semi-feral dogs. In one study of a group of free-ranging dogs, for the first 2 weeks immediately after parturition the lactating females were observed to be more aggressive to protect the pups. The male parents were in contact with the litters as ‘guard’ dogs for the first 6–8 weeks of the litters’ life. In absence of the mothers, they were observed to prevent the approach of strangers by vocalizations or even by physical attacks. Moreover, one male fed the litter by regurgitation showing the existence of paternal care in some free-roaming dogs. [82]

Space Edit

Space used by feral dogs is not dissimilar from most other canids in that they use defined traditional areas (home ranges) that tend to be defended against intruders, and have core areas where most of their activities are undertaken. Urban domestic dogs have a home range of 2-61 hectares in contrast to a feral dogs home range of 58 square kilometers. Wolf home ranges vary from 78 square kilometers where prey is deer to 2.5 square kilometers at higher latitudes where prey is moose and caribou. Wolves will defend their territory based on prey abundance and pack density, but feral dogs will defend their home ranges all year. Where wolf ranges and feral dog ranges overlap, the feral dogs will site their core areas closer to human settlement. [39]

Predation and scavenging Edit

Despite claims in the popular press, studies could not find evidence of a single predation on cattle by feral dogs. [39] [83] [84] However, domestic dogs were responsible for the death of 3 calves over one 5-year study. [84] Other studies in Europe and North America indicate only limited success in the consumption of wild boar, deer and other ungulates, however it could not be determined if this was predation or scavenging on carcasses. Studies have observed feral dogs conducting brief, uncoordinated chases of small game with constant barking - a technique without success. [39]

In 2004, a study reviewed 5 other studies of feral dogs published between 1975 and 1995 and concluded that their pack structure is very loose and rarely involves any cooperative behavior, either in raising young or in obtaining food. [85] Feral dogs are primarily scavengers, with studies showing that unlike their wild cousins, they are poor ungulate hunters, having little effect on wildlife populations where they are sympatric. [86] : 267 However, several garbage dumps located within the feral dog's home range are important for their survival. [87] Even well-fed domestic dogs are prone to scavenge gastro-intestinal veterinary visits increase during warmer weather as dogs are prone to eat decaying material. [88] Some dogs consume feces, which may contain nutrition. [89] [90] On occasion well-fed dogs have been known to scavenge their owners' corpses. [91]

Studies using an operant framework have indicated that humans can influence the behavior of dogs through food, petting and voice. Food and 20–30 seconds of petting maintained operant responding in dogs. [92] Some dogs will show a preference for petting once food is readily available, and dogs will remain in proximity to a person providing petting and show no satiation to that stimulus. [93] Petting alone was sufficient to maintain the operant response of military dogs to voice commands, and responses to basic obedience commands in all dogs increased when only vocal praise was provided for correct responses. [94]

A study using dogs that were trained to remain motionless while unsedated and unrestrained in an MRI scanner exhibited caudate activation to a hand signal associated with reward. [2] Further work found that the magnitude of the canine caudate response is similar to that of humans, while the between-subject variability in dogs may be less than humans. [95] In a further study, 5 scents were presented (self, familiar human, strange human, familiar dog, strange dog). While the olfactory bulb/peduncle was activated to a similar degree by all the scents, the caudate was activated maximally to the familiar human. Importantly, the scent of the familiar human was not the handler, meaning that the caudate response differentiated the scent in the absence of the person being present. The caudate activation suggested that not only did the dogs discriminate that scent from the others, they had a positive association with it. Although these signals came from two different people, the humans lived in the same household as the dog and therefore represented the dog's primary social circle. And while dogs should be highly tuned to the smell of items that are not comparable, it seems that the “reward response” is reserved for their humans. [96]

Research has shown that there are individual differences in the interactions between dogs and their human that have significant effects on dog behavior. In 1997, a study showed that the type of relationship between dog and master, characterized as either companionship or working relationship, significantly affected the dog's performance on a cognitive problem-solving task. They speculate that companion dogs have a more dependent relationship with their owners, and look to them to solve problems. In contrast, working dogs are more independent. [97]

Dogs in the family Edit

In 2013, a study produced the first evidence under controlled experimental observation for a correlation between the owner's personality and their dog's behaviour. [98]

Dogs at work Edit

Service dogs are those that are trained to help people with disabilities such as blindness, epilepsy, diabetes and autism. Detection dogs are trained to using their sense of smell to detect substances such as explosives, illegal drugs, wildlife scat, or blood. In science, dogs have helped humans understand about the conditioned reflex. Attack dogs, dogs that have been trained to attack on command, are employed in security, police, and military roles. Service dog programs have been established to help individuals suffering from Post Traumatic Stress Disorder (PTSD) and have shown to have positive results. [99]

The human-dog relationship is based on unconditional trust however, if this trust is lost it will be difficult to reinstate. [ citation needed ]

In the UK between 2005 and 2013, there were 17 fatal dog attacks. In 2007–08, there were 4,611 hospital admissions due to dog attacks, which increased to 5,221 in 2008–09. It was estimated in 2013 that more than 200,000 people a year are bitten by dogs in England, with the annual cost to the National Health Service of treating injuries about £3 million. [100] A report published in 2014 stated there were 6,743 hospital admissions specifically caused by dog bites, a 5.8% increase from the 6,372 admissions in the previous 12 months. [101]

In the US between 1979 and 1996, there were more than 300 human dog bite-related fatalities. [102] In the US in 2013, there were 31 dog-bite related deaths. Each year, more than 4.5 million people in the US are bitten by dogs and almost 1 in 5 require medical attention. A dog's thick fur protects it from the bite of another dog, but humans are furless and are not so protected. [103]

Attack training is condemned by some as promoting ferocity in dogs a 1975 American study showed that 10% of dogs that have bitten a person received attack dog training at some point. [104]

The number of factors that define diversity is truly unlimited. Throughout an individual’s life, the unique biological and genetic predispositions, experiences and education alter who they are as a person. These nature versus nurture interactions are what diversify and evolve the human race, allowing individuals to connect and learn from each other.

While such idiosyncrasies are infinite, there are a number of factors commonly discussed, considered and tracked. If you're looking to better understand the topic of diversity, you should know the following individual differences that are commonly considered when discussing diversity in the workplace .

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Cognitive disabilities

Cognitive disabilities, also known as intellectual functioning, are recognized by the EEOC when an individual meets this criteria :

  • Intellectual functioning level (IQ) below 70-75
  • Significant limitations in adaptive skills — the basic conceptual, social and practical skills needed for everyday life
  • Disability began before age 18

Different functioning may affect an individual’s memory, problem-solving abilities, attention, communication, linguistics, as well as verbal, reading, math and visual comprehension. However, having an intellectual disability does not mean the person is not capable of great success as an employee.

Some of the most famous and successful people in the world have cognitive disabilities ranging from Dyslexia, ADHD and Dyspraxia. To name a few: Satoshi Tajiri, the creator and designer of Pokemon, has Asperger's Syndrome Bill Gates, the founder of Microsoft, has Dyslexia Emma Watson, famous actress and activist, has ADHD .

Intellectual functioning can be difficult to notice, understand and communicate for both employees and employers, so it’s important to provide employees with a variety of tools and resources to can help them function optimally at their job. The Job Accommodation Network provides a list of possible accommodations employers can provide to support employees of all abilities.

Physical abilities & disabilities

Hiring individuals with varying disabilities and experiences will not only help your team build a more diverse and inclusive environment, but bring unique perspectives and ideas to help your company reach a wider market of customers and clients.

Start by checking how your company stands against the national Disability Equality Index . Also, consider some of these simple ways to boost disability inclusivity at your office and throughout your hiring process :

  • Establish an Employee Resource Group (ERG)
  • Offer comprehensive health benefit packages
  • Partner with disability advocacy groups
  • Design your website and application process with accessibility in mind
  • Create an internship program for people with disabilities

Additionally, ensure your office is ADA compliant and make available ramps, automated doors, visual aids, telephone headsets, screen readers as well as accommodations for service animals, so if a job seeker or employee requires an aid of some sort, you are prepared to support their needs.

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Mental health

Employee wellness is becoming a major trend in the HR space, but too often mental health is left out of the conversation. Without the support and resources to seek and receive the help employees need, companies may see an increase in absenteeism, work-family conflict, increased mental health and behavioral problems and even higher turnover rates.

To combat the stigma around mental health in the workplace, employers are improving resources, like insurance benefits, to cover mental health services and build a more inclusive company culture that supports mental health.


Neurodiversity, as defined by the National Symposium on Neurodiversity “is a concept where neurological differences are to be recognized and respected as any other human variation. These differences can include those labeled with Dyspraxia, Dyslexia, Attention Deficit Hyperactivity Disorder, Dyscalculia, Autistic Spectrum, Tourette Syndrome, and others.”

While there may be certain stereotypes and stigmas around neurodiverse individuals, research has found that some conditions , like autism and dyslexia, enhance an individual’s ability to recognize patterns, retain information and excel in math — all critical skills for any job .

Behavior & ethodiversity

Everyone has their own unique mannerisms and behavior patterns they develop throughout their lives. Such behaviors are a result of an individual's upbringing, family, friends, culture, etc., and they can be interpreted in different ways. This is an important element of diversity to recognize because while a behavior may seem ordinary or unremarkable to you, to someone else it may seem rude, odd or inappropriate.

For example, let's say you are on the elevator and your colleague doesn’t start a conversation with you. That doesn’t necessarily mean they are being rude, it may simply be uncomfortable or uncommon for them to converse in such close and brief quarters.

Behavioral diversity or ethodiversity can be highly specific and subtle between individuals. It’s important to remember that behavior is a result of a person's unique experiences, and if something feels odd, rude or inappropriate, consider politely asking them about why they do what they do rather than reacting negatively or being judgmental.

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Personality & thought-style

Bringing a variety of different personalities and thought-styles into a workplace can bring both stressful situations and genius creativity. To avoid the former, companies opt for hiring for culture fit, which consequently halt's the latter. Instead, companies should hire for culture add in pursuit of diverse personalities that work well together and challenge one another’s ideas and thoughts.

It's difficult to know a person’s personality and thought-style by their resume or even interview, which is why 22% of companies ask job candidates, as well as employees, to complete personality tests. Doing so helps companies understand their strengths, weaknesses and gaps and build a company culture that supports extroverts, introverts and everyone in-between.

While a number of companies boast about their team’s vast ‘diversity of thought,’ it shouldn’t be the only metric by which your team is measuring its diversity. Know that by hiring individuals with a wide range of diverse traits listed in this article, you will naturally acquire people with diverse personalities and thought-styles.

Cultural background

There are a number of factors that make up different cultures, including traditional food, language, religion and customs. The United States alone has several different cultures within each region, state and even town.

While a lot of people enjoy learning about other cultures for short time periods, it’s an entirely different experience to work with individuals on a daily-basis who come from different cultures.

Cultural differences can bring a wealth of learning opportunities as well as some complicated challenges and barriers among employees who are unfamiliar or uncomfortable with one another’s unique cultures. For example, cheek kisses are fairly common in French culture, and if you have a colleague or candidate who practices such behavior, they may view a cheek kiss as a friendly hello, whereas you may find that quite inappropriate at work.

Above everything, it's important to educate your team about different cultures and celebrate the differences. Additionally, creating a culture that encourages open communication will help employees explore each other's cultural differences without creating a hostile work environment.

Geographical location

Geographical location plays a major role in the culture, language, education, social roles, socioeconomic status, beliefs and ideologies with which a person is accustomed. Keep in mind that just because an individual lives in a particular location now, doesn’t mean they’ve always lived there. It’s important to get to know your candidates’ and colleagues’ rich history to better understand their unique experiences in life prior to working with you.

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Language, linguistics & accents

Reports from the United States Census Bureau found that at least 350 languages are spoken in the homes of Americans. Unlike most countries, and contrary to popular belief, the United States does not have an official language . However, language, linguistics and accents can play a significant role in an individual’s ability to get and keep a job.

For job seekers, if a job description or recruitment materials are only in one language, like English, it may be difficult for them to apply for a role or make it through an interview process . While it is not feasible for any company to translate all of their recruitment materials into 350+ different languages, it can be helpful to provide a few additional translations for common languages in your community and workplace. You may also consider utilizing an online translation service or in-person interpreter for roles that don’t require individuals to be fluent in a language to work.

Additionally, accents reflect the different ways individuals pronounce certain words within a language and such differences can lead to accent bias or perception , where people judge or discriminate against an individual’s intelligence and abilities simply by the way they pronounce certain words. Individual’s may also have an affinity for people who have a similar accent to their own. Understanding different accent biases will help you and your team to identify your own biases and challenge them when you meet people from different language backgrounds.


For starters, ethnicity is different from race, which we will cover in an upcoming section. Rather than biological factors, ethnicity is based on learned behaviors . Ethnicity is associated with culture, history, nationality, heritage, dress, customs, language, ancestry and geographical background. Common examples of ethnicity include: Hispanic or Latinx, Irish, Jewish, or Cambodian.

Unlike ethnicity, which we discussed earlier in this article, race is biologically determined. Examples of race include: White, Black or African American American, Indian or Alaska Native, Asian, Native Hawaiian or Other Pacific Islander.

Nadra Kareem Nittle provides a clear example of race versus ethnicity for Thought Co. stating that , “Race and ethnicity can overlap. For example, a Japanese-American would probably consider herself a member of the Japanese or Asian race, but, if she doesn't engage in any practices or customs of her ancestors, she might not identify with the ethnicity, instead considering herself an American.”

Citizenship status

In 1986, the Immigration Reform and Control Act (IRCA) was passed, making it illegal for employers to discriminate against candidates and employees when recruiting, referring, hiring or firing individuals based on their citizenship or immigration status. Even with such laws in place, citizenship status alone can play a significant role in foreign-born workers' ability to get a job or break past stereotypes related to immigrants and citizenship status .

In 2017, immigrants made up 13.6% of the U.S. population . Of those immigrants, 77% were lawful immigrants , 27% lawful permanent residents, 23% unauthorized immigrants and 5% were temporary lawful residents.

Gaining citizenship is certainly a challenging feat, and for those that do, the vast majority participate in the American workforce. In fact, foreign-born persons had a significantly lower unemployment rate at 3.5% in 2018, compared to native-born citizens at 4%.

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At any given time, there are several generations employed in the workforce. Each generation has its own distinct differences defined by the time period people were born and the unique social, political and economic changes that occurred during their upbringing.

In the workforce, such differences can pose challenges for individuals among generations. These challenges can turn into an unconscious bias known as ageism. Ageism in the workplace is defined as the tendency to have negative feelings about another person based on their age.

Stereotypes of different generations contribute to this bias. For example , baby boomers are seen as workaholics, Generation Xers are risk takers, millennials care about meaningful work and now Generation Zers ghost employers and seek job security. Such stereotypes can lead employers and colleagues to believe there are skills gaps and life milestones (like having children or retiring) that may affect certain age groups from excelling at their company.

While ageism can affect any member of the workforce, 58% of workers notice age bias when people enter their 50s. On the other hand, people under 25 years old are 2x less likely to experience age discrimination.

Family & upbringing

Family has a significant impact on every individual’s life. It plays a role in a person's upbringing and provides support throughout an individual’s life. While some families are biologically related, others are chosen.

No matter what an individual’s family situation is, as an employer, it’s important to understand that everyone has obligations outside of work to the ones they love. Not only that but by providing perks and benefits such as family medical leave, flexible work hours, child and elder care benefits, you will help employees foster close relationships with their family, thus enhancing their work-life balance and satisfaction.

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Ideologies are the conceptions an individual, group or culture have about different aspects of life. Most people have distinct economic, political and religious ideologies that are influenced by the people in their family, their upbringing, geographical location and education. Ideologies play a part in how often and comfortable employees share their opinions with colleagues. Vastly differing ideologies may make individuals more cautious to start a conversation with a coworker if they know it could lead to a heated debate.


Morals reflect an individual’s beliefs for acceptable thoughts and behaviors. Morals tend to reflect an individual’s upbringing, family, life experiences, income, ideologies, cultural background, citizenship status, privilege, personalities, socioeconomic status, social roles, as well as social, religious, political and worldly beliefs.

Most companies, seek individuals who share the same personal morals, values and ethics to align with the company’s core values . For employers, shared morals can alter how a company prioritizes its work and the impact it makes on the industry, local community and the world at large.

Social roles

Social roles are constructs that are influenced by certain demographics of an individual, such as age, behavior, gender and culture. A common example is that of gender roles , which are assigned to individuals the moment their sex is identified and have unique precepts that vary by culture. Stereotypes are often correlated with social roles held about a particular demographic and can affect an individual’s ability to move into certain professional roles, industries and face barriers, which is evident between men and women with the Glass Ceiling .

To become a true equal opportunity employer and support diversity and inclusion in the workplace, it’s important to become acutely aware of social roles and stereotypes unique to your culture, community, industry and workplace. Your team can help to break down barriers and open opportunities for people regardless of perceived social roles by attracting a diverse employee base in your recruitment materials. This trucking company did just that when they launched a recruitment campaign about women truckers to attract more female candidates.

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Gender identity

Gender roles are social constructs that vary by different cultures and are assigned to individuals at birth based on their biological sex. Once a child is assigned their gender, they are more or less segregated into either the male or female gender binaries.

Rather than these distinct binaries, popular belief finds that there is a spectrum of gender identities that may or may not correspond to the individual’s sex assigned at birth. A few common non-binary gender identities include: non-binary, transgender, gender-transition, gender queer, gender fluid and demigender, however there is a long list of other non-binary identities you should learn about . There are also ungender identities , such as agender , non-gendered, genderless and gender-free.

Such identities are defined by the individual and how they view and expect others to view themself. It’s important to keep in mind that individuals may identify differently from how you perceive their identity, so it's courteous to ask for people’s preferred pronouns as well as share your own.

Gender expression

Gender expression, which may be different from an individual’s sex or gender identity, refers to the external appearance of an individual’s gender identity. Gender expression may be interpreted through clothing, hair, makeup, voice, behavior, mannerisms, interests and preferred pronouns. Again, because you can not assume an individual's gender even based on their gender expression, it's important to ask for their preferred pronouns. For more information on how to become an inclusive workplace for all gender identities and expressions, check out the Human Rights Campaign's guide to gender identity & gender expression in the workplace.

Unlike gender identity and gender expression, sex refers to the biological and genetic differences between male and female bodies. More specifically, women are born with two X chromosomes and men are born with one X and one Y chromosome. Typically, once a child is assigned their gender based on biological sex, they are more-or-less segregated into either the male or female gender binaries.

However, contrary to popular belief, biology of sex, similar to gender, has a spectrum of differences that cannot be classified simply as man and woman. Some people who are born with a combination of sex characteristics and reproductive organs are classified on the genetic sex spectrum called intersex .

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Sexual orientation is also different from gender identity, gender expression and biological sex. Sexual orientation is defined by the Human Rights Campaign as “an inherent or immutable enduring emotional, romantic or sexual attraction to other people.” Common sexual orientations include heterosexual, gay, lesbian, bisexual, asexual, pansexual and questioning.

As of yet, less than half of U.S. states have laws in place that protect employees from discrimination based on sexual orientation and gender identity. That doesn’t mean employers can't create a diverse and inclusive workplace by:

  • Educating your team about different gender identity terms.
  • Asking candidates and employees about their gender pronouns.
  • Creating an Employee Resource Group to support the LGBTQIA+ individuals at your workplace.
  • Checking out these 50 ideas for building an inclusive workplace.
  • Utilizing executive bonuses t o support diversity goals.
  • Learning about current issues and laws related to LGBTQIA+ employees.
  • Implementing unconscious bias training, but also learning about some of the critiques of unconscious bias training.


Education varies greatly by location, school and teacher, and can be heavily influenced by national, state and district laws and requirements. This means that no single individual will have the exact same education. Not only that, but high-level education can be extremely expensive and unattainable for a significant part of the American population, and for upper-level jobs (or even entry-level jobs) post-high school degrees are often required.

The Bureau of Labor Statistics found in 2015 that the correlation between the level of education and unemployment rate is quite startling.

Image via bureau of labor statistics

The average cost of a four-year college degree continues to rise, leaving recent grads who took out loans to pursue their dreams with on average, $29,800 of debt as of 2018. Not surprisingly, many talented young professionals are looking for alternative career paths that don’t require such exorbitant costs.

On the flip side, employers are creating opportunities to help such professionals bypass college in exchange for applicable experiences.

Some companies no longer require candidates to complete a Bachelor’s or Master’s degree to compete for a role. Instead, companies are focusing on experiences, as well as hard and soft skills to qualify candidates. Additionally, removing education requirements allows candidates with more diverse , non-traditional backgrounds to apply.


Income plays a major role in every individual’s life starting from the day they are born and throughout their upbringing, professional career and into retirement. Income can be affected by geographical location, taxes, family, education, skills and socioeconomic background. Unconscious biases related to an individual's age, gender, gender identity and expression, sexual orientation, race, ethnicity and privilege can also affect their income.

In 2019, the Paycheck Fairness Act (PFA), first devised in 1997, was passed. This act builds upon existing legislation with three key components:

  1. It prohibits employers from asking candidates how much they previously made.
  2. It allows employees to share their pay with work colleagues.
  3. It requires employers to disclose all pay information with the Equal Employment Opportunity Commission.

Other income-based laws you should know about include the the Equal Pay Act of 1963, which prohibits pay discrimination based on gender and the Lilly Ledbetter Fair Pay Act of 2009, which prohibits gender-based wage discrimination and allows workers to sue for discrimination. While these acts are certainly steps in the right direction, there is still work to be done. Just check out this graph below for discrepancies in pay based on gender, race and ethnicity in the United States in 2018.

Content via IWPR Image via Built In

Socioeconomic status

Socioeconomic status (SES) is the measurement and categorization of people based on their education, income and occupation. It is also a strong indicator of privilege, as well as the opportunities and resources an individual has access to in order to excel at school and work.

Additionally, SES is found to contribute significantly to one’s mental health, physical health, stress, performance and functioning both in the workplace and in life.

To support candidates and employees of all SES, it’s important to consciously create and distribute recruitment content that will reach and resonate with individuals of varying SES. As an employer, make sure to provide adequate salaries, benefits and resources to help individuals who are impacted by their own SES.

Life experiences

Life experiences encompass all of the unique work, education, military, private and public occurrences an individual undergoes throughout their life that contributes to who they are, how they view the world and how they interact with others.


Privilege refers to social power that can be inhibited or compounded based on an individual’s sex, gender identity, race, ethnicity, religion, age, citizenship status, socioeconomic status, social role, cultural background and disability status. Privilege can affect a person’s ability to obtain certain levels and quality of education, jobs, higher income and opportunities throughout life.

For employers, it is important to consider an individual’s privilege and the opportunities they may or may not have access to due to their personal demographics. Let’s not forget the recent college admissions scandal , which is an excellent example of how privilege and opportunity — rather than merit — can provide some individuals with more highly regarded experiences than others.

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Marital status

Marriage is a major event for many people. Not only that, but getting married, divorced, separated or becoming widowed can alter an individual’s beliefs, geographical location, income, parental status, family, citizenship status, socioeconomic status, privilege, family and even behaviors.

Similar to gender bias, marital status bias can prevent highly qualified individuals from getting a job or excelling in their career. And while there are national laws that prohibit employers from discriminating against an individual’s gender, sex and sexual orientation , only some states have specific laws prohibiting marital status discrimination in the workplace.

Marital status can especially affect an individual in the workplace if their partner also works in the same place. Some companies have an anti-nepotism policy in place to prevent a family member from working on the same team or in hierarchy to one another.

Parental status

While parental status can affect both mothers and fathers, in particular, pregnant women, working mothers and women of childbearing age face a motherhood penalty or maternal wall . Stereotypes related to a woman’s role and needing time off after childbirth and for childcare often place women at a disadvantage in their careers compared to men and fathers.

Not only that, but female candidates are more likely to be asked questions about their parental plans and responsibilities during an interview. Even though discriminating against parents and pregnant people is illegal , inquiring about a job seeker’s parental status technically isn’t illegal .

In addition to working mothers, 54% of women with a young child leave their job because they need to care for their child. For individuals who take a large chunk of time off to fulfill caregiving needs, it can be extremely difficult for them to explain the gaps in their resume and find employers willing to support them as they reenter their career.

Employers can support working parents by reducing unconscious bias against them and by providing benefits like flexible work hours, childcare benefits, parental leave and adoption assistance to ease the challenges that working parents face and keep top employees in its workforce.

Military experience

Military veterans offer a wealth of skills, knowledge and experience, making them exceptional contributions to any role or company. However, many employers are unfamiliar with military culture, experiences or common military language , which may make it difficult for them to understand the value such individuals can bring to a company. There are a number of resources available to help employers better understand how military skills are relevant to a specific role role, such as this military skills translator and this skills matcher .

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Criminal background

The unemployment rate for people ages 25-44 who have formerly been incarcerated is more than five times higher than the national average. These individuals are in their prime working age but are struggling to find a company that will hire them with a criminal background.

And while some states provide incentives by offering tax breaks for companies that hire candidates with felony convictions, other states allow employers to require criminal history on job applications, perpetuating issues of social bias. In recent years, politicians from both sides have made efforts to support incarcerated individuals, from Obama’s Fair Chance Business Pledge (2016) to Trump’s First Step Act (2018). Today, however, it’s still up to employers to decide whether or not they will allow an individual’s past prevent them from excelling in a rewarding career in the future.

Political beliefs

There are a lot of different opinions on how, when and if politics should be allowed in the workplace. For some, such discussions are a great way to connect with and engage in stimulating conversations unrelated to work. However, when colleagues have radically different political affiliations and views, controversy can erupt, making the workplace uncomfortable at best and unbearable at worst.

Not only that, but bringing politics into the workplace can lead to issues around political affiliation discrimination . And while there is no national law that prohibits employers from discriminating against a candidate or employee based on their political affiliation, a few states do .

All that being said, it can be extremely difficult to eliminate all traces of politics from the workplace. A lot can and is assumed about an individual’s political affiliation based on their resume and personal interests. But is eliminating all politics really the answer? Just like every other element of diversity on this list, political diversity is also important for providing unique ideas, morals and beliefs to the workplace and fostering a truly diverse and inclusive workplace.

Religious & spiritual beliefs

Whether or not people discuss their religious affiliations at work, it’s important to create a workplace that is understanding and accepting of everyone’s beliefs, even if they are different from one another.

Employers can do this by offering floating holidays so that employees can take time off for religious holidays and celebrations when they need. It’s also important to respect individuals who wear religious clothing at work and ensure they are treated fairly and equally by their cohorts. Depending on your office and building layout, consider creating a space for private religious and spiritual practice so employees have a space to go during the day, and don’t have to leave work or disrupt colleagues.

W ork experiences

There’s no doubt that every single workplace is different. Every company has their own unique mission, core values , policies, culture and benefits, which vary by region, industry, size and employer. Each time an employee moves into a new role, industry or company, they bring their previous work experiences and skills with them.

For employers, it’s often beneficial to attract talent with diverse work experience, even hiring out-of-market candidates . Such experiences can help your team better understand different aspects of your own industries or reach new customer markets, so don’t count candidates out just because they have different workplace experiences.


Skill set is a less obvious type of diversity, but one that is hugely important to the recruitment process. Depending on their professional history, candidates will have a particular skill set. However, based on their personal experiences and background, they’ll have a vastly different set of strengths that can benefit your business and culture. Suss out individual skills — emotional intelligence, budding leadership abilities and the like — to create a positive culture that allows employees to excel.

While some skills are innate, others are learned. In the workplace, we tend to focus on the skills that directly apply to one’s specific role. However, there are a number of other skills an individual picks up on through their personal interests and experiences that make them excellent at their job. If you are able to hone in on these unique skills and encourage employees to bring them to work, your team will surely excel in innovation and creativity.

It’s important to remember that individual differences are what make each of your team members unique and providing a workplace that allows for individuals to excel will only help your team grow and innovate. Individuals of all types of diversity on this list will experience different types of bias, which can affect their ability to excel in the workplace. When you are building out a diverse and inclusive workforce, make sure to continuously educate your team on why diversity and inclusion matters so everyone is on the same page.

Teeth and Mouth

Adult dogs have incisors, canines, premolars, and molars.

Like their wolf ancestors, dogs are carnivores with teeth designed for rending and tearing meat. They have 28 deciduous (baby) teeth that are replaced by 42 permanent (adult) teeth between 2 andه months of age (see Table: Canine Adult Dentition). The different types of teeth have specialized functions, depending on their position in the mouth. The front teeth, which include the 12 incisors and 4 large canine teeth (eye teeth), are designed for grasping and tearing. The rearward premolar and molar teeth grind food into smaller pieces that can be swallowed.

Canine Adult Dentition

The mouth also contains the salivary glands, which secrete saliva that lubricates the food and begins digestion. The tongue helps guide food to the back of the throat and is important for licking up small food pieces and lapping up water. Dogs also lick as a sign of affection or subservience, or both.

Do Dog Breeds Have Personalities? Data on 17,000 Pups Shows Genetic Roots

It doesn’t take a scientist to tell you that golden retrievers are usually friendly and that you shouldn’t aggravate a pit bull. There are exceptions, of course, but the personality types associated with different dog breeds generally hold true. Now, an unprecedented analysis of 17,000 dogs confirms why it’s so consistent: Much of their personality is actually written in their DNA.

The co-lead author of the bioRxiv preprint, Evan MacLean, Ph.D., is a comparative psychologist at the University of Arizona in Tucson and the owner of two dogs with big personalities, a Labrador retriever (friendly, active, outgoing, according to the American Kennel Club), and a Yorkshire terrier (affectionate, sprightly, tomboyish). In the study, also led by Noah Snyder-Mackler, Ph.D., an assistant professor at the University of Washington, the team compared the personalities of 17,000 dogs of different breeds with the genomes of around 5,700 dogs to find a relationship between DNA and their traits. They found multiple: 131 sections of dog DNA that line up with 14 personality traits, across breeds.

“Our findings suggest that there are certainly genetic influences on dog behavior, and dog owners are never working with a ‘blank slate’,” MacLean tells Inverse.

What makes the study different from previous research on dog personalities is that it examines how dog genomes and personality traits vary across breeds rather than within a breed. Doing so, he says, is a better indicator of the “heritability” of a trait — a measure of how well differences in a dog’s genes accounts for differences in its traits. Just as you wouldn’t study the genetics of eye color in a family of purely brown-eyed people, it doesn’t make sense to study the genetics of dog behavior among similarly behaved dogs of the same breed. Better to study different breeds, so you can see how much of a role genes play in behavior.

The personality “traits,” or dog behaviors, that the team focused on were determined by the C-BARQ (Canine Behavioral Assessment & Research Questionnaire) project, which compiles personality data from about 50,000 dogs of 300 different breeds and cross-breeds, as described by their owners. The 14 traits aren’t quite like the American Kennel Club’s descriptive adjectives rather, they break those descriptors down into traits shared among dogs.

In the analysis of the 14 traits, trainability, chasing, and aggression seemed to be the most heritable — that is, they were most embedded in differences in the dog genome across breeds. The other traits have to do with dog rivalry fear of strangers, settings, and other dogs attachment and attention-seeking touch sensitivity and energy level.

MacLean points out that there are no genes specifically for any of these traits only genes related to these behaviors. “Dogs faced natural problems that required learning, protective behaviors and predatory behaviors etc. long before humans were trying to sculpt any of those traits,” he says. “Natural variance in these types of behaviors may have provided the raw material for breeders to work with in developing dog breeds for more specific functions.”

Unfortunately for owners who can’t deal with their pet’s personality, this means that sometimes, there’s not much you can do to change how a pet behaves. “Certain breeds are more inclined to engage in certain behaviors, which can be frustrating if it’s a behavior the owner is struggling with,” MacLean says.

That said, even though the analysis shows that certain personality traits are rooted in the genomes of individual breeds, he adds it’s “a mistake to overlook the enormous amount of variation within breeds as well.” As the occasionally aggressive golden retriever and docile pit bull illustrates, genes aren’t everything. “While one breed may exhibit more or less of a particular behavior on average, you never know exactly what you are going to get in any individual dog — you only know, on average, what you might expect to get,” he says.

“So, if you are looking for a dog that has particular characteristics, you can make an educated guess based on breed, but it’s never a guarantee.”

At the end of the day, there will be differences in the inherited behavioral differences among breeds, but MacLean doesn’t think this means that some good boys and girls are better than others. “Different dogs will do different things,” he says, “but to me, thats one of the great marvels and joys of having such an interesting and diverse species to share our lives with.”

Genetic basis of morphological diversity in the domestic dog

Despite the high level of phenotypic variation among breeds, genetic divergence within the domestic dog and between most species of the genus Canis is quite low. All species of Canis have identical karyotypes [30] and genetic comparisons based on mitochondrial and nuclear genes reveal low levels of divergence between members of this genus [11, 22, 31]. In part, this level of genetic similarity explains the level of inter-fertility seen among species of Canis. As suggested by Gray et al. [32], the dog experienced two population bottlenecks, the first associated with domestication and the second with the formation of various breeds, with the latter responsible for most of the loss in genetic diversity. This has resulted in much higher linkage disequilibrium in dogs compared to humans [13]. Although mtDNA markers fail to reveal breed-specific markers [11], both microsatellite loci [33] and SNPs [15] are capable of assigning individual purebred dogs to their specified breed. Nevertheless, genetic markers to date are considerably less effective at providing well-supported phylogenetic groups of breeds, primarily as a result of most breeds differing more by allele frequency than fixed differences. Therefore, reconstructing the overall phylogeny of domestic dogs is considerably more complicated as a result of the recent origin of many breeds coupled with high levels of admixture during breed formation.

Deciphering the underlying genetic causes of morphological diversity in the domestic dog presents considerable challenges. Top-down approaches [34], using a QTL mapping, linkage disequilibrium mapping and association analyses are all methods that take advantage of the dog genome sequence. Furthermore, such methods bypass the need for large pedigrees. Such an approach has proven useful in identifying candidate genes and the mutations responsible for traits associated with spotting and the hair ridge in Rhodesian ridgebacks [18]. These same methods allowed Sutter et al. [21] and Gray et al. [20] to identify a chromosomal region whose variation appears to be associated with size differences in dogs. Despite these advances as a result of comparative genomics and marker-assisted mapping, deciphering the mechanisms responsible for the origin of form in the domestic dog will be challenging. For instance, the QTL identified by Sutter et al. [21] appears to be associated with size, yet variation at the IGF1 locus does not appear to be 'a major contributor to body size in all small dogs'. Association analyses are an excellent first approximation but multifactorial traits resulting from gene/environment interactions and epistasis complicate our understanding of the genetic basis of form.

As stated by Carroll [35], 'The key to understanding form is development'. The question still remains - What processes are responsible for the diversity of forms observed in the domestic dog? Rather than major modifications in structural genes, changes may be considerably more subtle and involve changes in the timing of gene expression, the alteration of interactions among various gene products and variation in regions of genes controlling development. Such changes might allow for changes in the phenotype without major genetic divergence. The domestic dog may very well offer clues to the types of changes in form observed in nature, such as those observed for the mammalian radiations, and this is the reason why continued research on genes controlling development in dogs is an exciting avenue of research.

Watch the video: How Different Are Different Types of Dogs? (August 2022).