From Wikipedia, the free encyclopedia
(Canis lupus familiaris
pronounced /ˈkeɪ.nɪs ˈluːpəs fʌˈmɪliɛərɪs/
) is a domesticated form
of the wolf
member of the Canidae
of the order Carnivora
The term is used for both feral
varieties. The domestic dog
has been one of the most widely kept working
and companion animals in human
history. Amongst canine enthusiasts, the word "dog" may also mean
the male of a canine species, as opposed to the word "bitch
" for the female of the
The dog quickly became ubiquitous across culture across the
world, and was extremely valuable to early human settlements. For
instance, it is believed that the successful emigration across the
might not have been possible without sled dogs
Dogs perform many roles for people, such as hunting
, protection, assisting police and military
, and, more recently, aiding handicapped
. This versatility, more than almost any other known
animal, has given them the nickname "Man's best friend" in the
western world. Currently, there are estimated to be 400 million
dogs in the world.
Over the 15,000 year span that the dog had been domesticated, it
diverged into only a handful of landraces
, groups of similar animals whose morphology
and behavior have been
shaped by environmental factors
functional roles. As the modern understanding of genetics
developed, humans began to intentionally breed dogs for a wide
range of specific traits. Through this process, the dog has
developed into hundreds of varied breeds
, and shows more behavioral and
morphological variation than any other land mammal.
For example, height measured to the withers
ranges from a few inches in the Chihuahua
few feet in the Irish Wolfhound
; color varies from
white through grays (usually called "blue'") to black, and browns
from light (tan) to dark ("red" or "chocolate") in a wide variation
of patterns; coats
be short or long, coarse-haired to wool-like, straight, curly, or
common for most breeds to shed
this coat, but non-shedding breeds are
is the common use term that refers to members of
the subspecies Canis lupus familiaris
. The term is
sometimes used to refer to a wider range of species: it can be used
to refer to some belonging to the family Canidae, which includes foxes
, Bush Dog
, the cape dog Lycaon
and many others; or it can be used to
refer to the subfamily of Caninae, or the genus Canis, also often
called the "true dogs," which genus includes only the wolf, jackal,
coyote, and dog.
members of the family have "dog" in their common names, such as the
. A few animals have "dog" in their common names but are not
canids, such as the prairie dog
and the dog fish
The English word dog
comes from Middle English
, from Old
, a "powerful dog breed".
term may derive from Proto-Germanic *dukkōn
in Old English finger-docce
word also shows the familiar petname diminutive -ga
also seen in
"beetle, worm", among others.
the archaic structure of the word, the term dog
ultimately derive from the earliest layer of Proto-Indo-European
vocabulary, reflecting the role of the dog as the earliest domesticated animal
traditionally the general word for all domestic canines, and
was reserved for mastiffs and similar breeds. By the
16th century, dog had become the general word, and hound had begun
to refer only to types used for hunting. Hound
to German Hund
, common Scandinavian hund
, and Icelandic
, is ultimately derived from the Proto-Indo-European
"dog", found in Welsh ci
, Lithuanian šuõ
In breeding circles, a male canine is referred to as a
, while a female is called a bitch
English bicche, from Old English bicce, ultimately from Old Norse
bikkja). A group of offspring is a litter
. The father of a litter is
called the sire
, and the mother is called the
. Offspring are generally called pups
, from French
, until they are about a year old. The process of
birth is whelping
, from the Old English word
, (cf. German Welpe, Dutch welp, Swedish valp,
Icelandic hvelpr) .
The domestic dog was originally classified as Canis
and Canis familiarus domesticus
by Carolus Linnaeus
was reclassified in 1993 as Canis lupus familiaris
subspecies of the gray wolf Canis lupus
, by the Smithsonian Institution
American Society of
. Overwhelming evidence from behavior,
vocalizations, morphology, and molecular biology
led to the
contemporary scientific understanding that a single species, the
gray wolf, is the common ancestor
for all breeds of
however, the timeframe and mechanisms by which dogs diverged are
Some new evidence, however, exists that the Indian Wolf
, Canis indica, was domesticated
early on and played a role in the ancestry of some dog breeds,
especially those which originated in Southeast Asia, which is
outside the range of the gray wolf.
this turns out to be true, it would rule against the unilateral use
of the species name lupus in the classification of the dog.
A hunter with a large pack of beagles
, a breed of hunting dogs
Domestic dogs inherited a complex social hierarchy
and behaviors from their wolf ancestors. Dogs are pack animals with
a complex set of behaviors related to determining each dog's
position in the social hierarchy, and they exhibit various postures
and other means of nonverbal communication
reveal their states of mind.
These sophisticated forms of social cognition and communication may
account for their trainability, playfulness, and ability to fit
into human households and social situations, and these attributes
have earned dogs a unique relationship with humans despite being
potentially dangerous apex predators
Although experts largely disagree over the details of dog
domestication, it is agreed that human interaction played a
significant role in shaping the subspecies.
Shortly after domestication, dogs became ubiquitous in human
populations, and spread throughout the world. Emigrants from
Siberia likely crossed the Bering Strait
with dogs in their company,
and some experts suggest that use of sled dogs may have been
critical to the success of the waves that entered North America
roughly 12,000 years ago. Dogs were an important part of life for
population in North
America, and were their only domesticated animal. Dogs also carried
much of the load in the migration of the Apache
tribes 1,400 years ago. Use of
dogs as pack animals in these cultures often persisted after the
introduction of the horse
The current consensus among biologists and archaeologists is
that no one can be sure when dogs were domesticated.
There is conclusive evidence that dogs genetically diverged from
their wolf ancestors at least 15,000 years ago
but some believe domestication to have occurred earlier.
It is not known whether humans domesticated the wolf as such to
initiate dog's divergence from its ancestors, or whether dog's
evolutionary path took a different course already prior to
domestication. Lately the latter view has gained proponents such as
biologists Raymond and Lorna Coppinger.
They theorize that some wolves started gathering around the
campsites of the paleolithical man to scavenge his refuse. There,
an evolutionary pressure developed that favored those who were less
frightened by and keener in approaching humans.
The bulk of the scientific evidence for the evolution of the
domestic dog stems from archaeological findings and mitochondrial
studies. The divergence date of roughly 15000 years ago is
based in part on archaeological evidence that demonstrates that the
domestication of dogs occurred more than 15,000 years ago,
and some genetic evidence indicates that the domestication of dogs
from their wolf ancestors began in the late Upper
close to the Pleistocene
boundary, between 17,000 and 14,000
But there is a wide range of other, contradictory findings that
make this issue controversial.
Archaeological evidence plays a large role in this debate. In
2008, a team of international scientists released findings from an
excavation at Goyet Cave in Belgium declaring that a large, toothy
canine existed 31,700 years ago and ate a diet of horse, musk ox
to this Belgium discovery, the earliest dog fossils were two large
skulls from Russia and a mandible
from Germany, that dated from roughly
14,000 years ago.
Remains of smaller dogs from Natufian
cave deposits in the Middle
East, including the earliest burial of a human being with a
domestic dog, have been dated to around 10,000 to 12,000 years
is a great deal of archaeological evidence for dogs throughout
Europe and Asia around this period and through the next two
thousand years (roughly 8,000 to 10,000 years ago), with fossils
uncovered in Germany, the French Alps, and Iraq, and cave paintings
This ancient mosaic, likely Roman, shows a large dog with a collar
hunting a lion.
Thus, the archaeological evidence suggests that the latest dogs
could have diverged from wolves was roughly 15000 years ago,
although it is possible that they diverged much earlier.
DNA studies have provided a wider range of possible divergence
dates, from 15,000 to 40,000 years ago,
to as much as 100,000 to 140,000 years ago.
evidence depends on a number of assumptions that may be
Genetic studies are based on comparisons of genetic
between species, and depend on a calibration date.
Many estimates of divergence dates from DNA evidence use an
estimated wolf-coyote divergence date (roughly 1 million years ago)
as a calibration. If this estimate is incorrect, and the actual
wolf-coyote divergence is closer to 750,000 or 2 million years ago,
then the DNA evidence that supports specific dog-wolf divergence
dates would be interpreted very differently. Furthermore, it is
believed that the genetic diversity of wolves has been in decline
for the last 200 years, and that the genetic diversity of dogs has
been reduced by selective breeding
. This could
significantly bias DNA analyses to support an earlier divergence
date. The genetic evidence for the domestication event occurring in
East Asia is also subject to violations of assumptions. These
conclusions are based on the location of maximal genetic
, and assume that hybridization does not occur, and
that breeds remain geographically localized. Although these
assumptions hold for many species, there is good reason to believe
that they do not hold for canines.
Genetic analyses indicate all dogs are likely descended from a
handful of domestication events with a small number of founding
although there is evidence that domesticated dogs interbred with local
of wild wolves on several occasions.
Data suggests that dogs first diverged from wolves in East Asia,
and that these domesticated dogs then quickly migrated throughout
the world, reaching the North American continent around 8000
The oldest groups of dogs, which show the greatest genetic
and are the most similar to their wolf ancestors,
are primarily Asian and African breeds, including the Basenji
, Lhasa Apso
, and Siberian Husky
Some breeds that were thought to be very old, such as the Pharaoh Hound
, Ibizan Hound
, and Norwegian
, are now known to have been created more recently.
There is a great deal of controversy surrounding the
evolutionary framework for the domestication of dogs.
Although it is widely claimed that "man domesticated the wolf,"
man may not have taken such a proactive role in the process.
The nature of the interaction between man and wolf that led to
domestication is unknown and controversial. At least three early
species of the Homo
genus began spreading out of Africa
roughly 400,000 years ago, and thus lived for a considerable period
in contact with canine species. Despite this, there is no evidence
of any adaptation of canine species to the presence of the close
relatives of modern man. If dogs were domesticated, as believed,
roughly 15,000 years ago, the event (or events) would have
coincided with a large expansion in human territory and the
development of agriculture. This has led some biologists to suggest
that one of the forces that led to the domestication of dogs was a
shift in human lifestyle in the form of established human
settlements. Permanent settlements would have coincided with a
greater amount of disposable food and would have created a barrier
between wild and anthropogenic canine populations.
Domesticated dogs got advantages that wolves never had—more
safety, more reliable food, lesser caloric needs, and more chance
to breed. Humans have an upright gait that give them larger range
over which to see both potential predators and prey, as well as color vision
least by day give humans better warning of predators that could be
dangerous to both humans and dogs. With their tool use, humans
could get dogs to take more specialized roles in a hunt. Humans and
dogs together could hunt prey that neither humans nor wolves could
detect and subdue without aid from the other. Dogs and humans
together out-competed other large predators and crowded wild
, and big cats
out in their range and
thus share the top of the food chain.
Human families and wolf packs have similar structures, but
unlike the wolf pack, the human family did not suppress the mating
of canine associates even if a man and woman had the dog in clear
subordination. The sorts of canines that might never bred had they
been in a wolf pack were able to breed earlier and more often.
Although humans could never travel at the pace of wolves or dogs,
they did not need to travel as far to find prey.
Dogs have lived and worked with humans in so many roles that
they have earned the unique nickname, "man's best friend",
phrase which is used in other languages as well. They have been
bred for herding livestock,
hunting (e.g. pointers and hounds),
guarding, helping fishermen with nets, and pulling loads, in
addition to their roles as companions.
as guide dogs
dogs, assistance dogs, hearing dogs, and psychological therapy dogs
provide assistance to individuals with physical or mental
dogs owned by epileptics have been shown to alert their handler
when the handler shows signs of an impending seizure, sometimes
well in advance of onset, allowing the owner to seek safety,
medication, or medical care.
Owners of dogs often enter them in competitions
as breed conformation shows or sports
, including racing and
In conformation shows, also referred to as breed shows, a judge
familiar with the specific dog breed evaluates individual purebred
dogs for conformity with their established breed type as described
in the breed standard. As the breed standard only deals with the
externally observable qualities of the dog (such as appearance,
movement, and temperament), separately tested qualities (such as
ability or health) are not part of the judging in conformation
As a food
A dish made with dog meat
in South Korea
Dog meat is consumed in some East Asian countries, including
Korea, China, and Vietnam, a practice that dates back to
estimated that 13–16 million dogs are killed and consumed in Asia
BBC claims that, in 1999, more than 6,000 restaurants served soups
made from dog meat in South Korea.
In Korea, the primary dog breed raised for meat, the
(누렁이), differs from those breeds raised for pets
which Koreans may keep in their homes.
most popular Korean dog dish is gaejang-guk
), a spicy stew meant to balance the body's heat
during the summer months; followers of the custom claim this is
done to ensure good health by balancing one's gi
, or vital energy of the body. A 19th century
version of gaejang-guk
explains that the dish is prepared
by boiling dog meat with scallions
and chili powder. Variations of the
dish contain chicken and bamboo shoots. While the dishes are still
popular in Korea with a segment of the population, dog is not as
widely consumed as beef, chicken, and pork.
Other cultures, such as Polynesia
and Pre-Columbian Mexico
consumed dog meat in their history. However, Western, South Asian,
African, and Middle Eastern cultures generally regard consumption
of dog meat as taboo
. In some places, however,
such as in rural areas of Poland, dog fat is believed to have
medicinal properties - being good for the lungs for instance.
risks to humans
In the USA, cats and dogs are a factor in more than 86,000 falls
each year in the USA.
feces can cause a number of human diseases, including toxocariasis
can cause blindness, and can also contain hookworms
that cause cutaneous larva migrans
the United States, about 10,000 cases of Toxocara infection are
reported in humans each year. Almost 14% of the US population is
infected with Toxocara, a parasite of dogs and cats that can be
passed from animals to humans.
The incidence of dog bites, and especially fatal dog bites, is
extremely rare in America considering the number of pet dogs in the
Fatalities from dog bites occur in America at the rate of one per
four million dogs.
A Colorado study found that bites in children were less severe than
bites in adults.
incidence of dog bites in the US is 12.9 per 10,000 inhabitants,
but for boys aged 5 to 9 the incidence rate is 60.7 per 10,000.
Moreover, children have a much higher chance to be bitten in the
face or neck.
claws with powerful muscles behind them can lacerate flesh in a
scratch that can lead to serious infections.
In the UK between 2003 and 2004, there were 5,868 dog attacks
resulting in 5,770 working days lost in sick leave.
Main article: Dog anatomy
Domestic dogs have been selectively bred for millennia for
various behaviors, sensory capabilities, and physical
Modern dog breeds
more variation in size, appearance, and behavior than any other
domestic animal. Nevertheless, their morphology is based on that of
their wild ancestors, gray wolves.
Dogs are predators
, and like
many other predatory mammals, the dog has powerful muscles, fused
wrist bones, a cardiovascular system that supports both sprinting
and endurance, and teeth for catching and tearing. Dogs are highly
variable in height and weight. The smallest known adult dog was a
, that stood only 6.3 centimetres (2.5 in) at
the shoulder, 9.5 cm (3.7 in) in length along the
head-and-body, and weighed only 113 grams (4.0 oz). The
largest known dog was an English Mastiff
155.6 kilograms (343 lb) and was 250 cm (98 in)
from the snout to the tail.
The tallest dog is a Great
that stands 106.7 cm (42.0 in) at the
The dog's visual system has evolved to aid proficient
While a dog's visual
is poor (that of a poodle
's has been estimated to translate to a Snellen
their visual discrimination for moving objects is very high; dogs
have been shown to be able to discriminate between humans (e;g.
identifying their owner) from distances up to a mile.
hunters, dogs often rely on their vision in low light situations:
they have very large pupils, a high density of rods
in the fovea
, an increased flicker rate, and a tapetum
The tapetum is a reflective surface behind the retina that reflects
light back to give the photoreceptors a second chance to catch the
The eyes of different breeds of dogs have different shapes,
dimensions, and retina configurations.
long-nosed breeds have a "visual streak" – a wide foveal region
that runs across the width of the retina and gives them a very wide
field of excellent vision. Some long-muzzled
breeds, particularly the sighthounds
, have a field
of vision up to 270° (compared to 180° for humans). Short-nosed
breeds, on the other hand, have an "area centralis": a central
patch with up to three times the density of nerve endings as the
visual streak, giving them detailed sight much more like a human's.
breeds with short noses
have a field of vision similar to that of humans.
Most breeds have good vision
, but some show a genetic predisposition
– such as Rottweilers
, where one
out of every two has been found to be myopic.
The frequency range of dog hearing is approximately 40 Hz
to 60,000 Hz,
which means that dogs can detect sounds far beyond the upper limit
of the human auditory spectrum.
Additionally, dogs have ear mobility which allows them to rapidly
pinpoint the exact location of a sound.
Eighteen or more muscles can tilt, rotate, raise, or lower a dog's
ear. A dog can identify a sound's location much faster than a human
can, as well as hear sounds at four times the distance.
While the human brain is dominated by a large visual cortex
dog brain is dominated by an olfactory cortex
in dogs is roughly forty times bigger than the olfactory
bulb in humans, relative to total brain size, with 125 to 220
million smell-sensitive receptors.
this standard with nearly 300 million receptors.
Dogs can discriminate odors at concentrations nearly 100 million
times lower than humans can.
The wet nose is essential for determining the direction of the air
current containing the smell. Cold receptors in the skin are
sensitive to the cooling of the skin by evaporation of the moisture
by air currents.
A heavy winter coat with countershading in a mixed breed
of domestic dogs are either "double",
made up of a coarse guard
and a soft down
, like a wolf, or "single", with the topcoat only. Dogs
with double coats tend to originate in colder climates.
Domestic dogs often display the remnants of countershading
common natural camouflage pattern. A countershaded animal will have
dark coloring on its upper surfaces and light coloring below,
which reduces its general visibility. Thus many breeds will have an
occasional "blaze", stripe, or "star" of white fur on their chest
There are many different shapes for dog tails: straight,
straight up, sickle, curled, or cork-screw. In some breeds, the
tail is traditionally docked
to avoid injuries (especially for
some breeds, puppies can be born with a short tail or no tail at
occurs more frequently in those breeds that are frequently docked
and thus have no breed standard
regarding the tail.
While all dogs are genetically very similar,
and selective breeding have reinforced certain
characteristics in certain populations of dogs, giving rise to dog
types and dog breeds. Dog types are broad categories based on
function, genetics, or characteristics.
are well known for
their short muzzles.
Dog breeds are groups of animals that possess a set of inherited
characteristics that distinguishes them from other animals within
the same species. Modern dog breeds are non-scientific
classifications of dogs kept by modern kennel clubs
. Purebred dogs of one breed
are genetically distinguishable from purebred
dogs of other breeds,
but the means by which kennel clubs classify dogs is unsystematic.
Systematic analyses of the dog genome has revealed only four major
types of dogs that can be said to be statistically distinct.
These include the "old world dogs" (e.g., Malamute
), "herding"-type (e.g., Border Collie
), and "all others" (also
called "modern"- or "hunting"-type).
Some breeds of dogs are prone to certain genetic ailments such
as elbow or hip dysplasia
deafness, pulmonic stenosis
, and trick knees
. Two serious medical
conditions particularly affecting dogs are pyometra
, affecting unspayed
females of all types and ages, and
bloat, which affects the larger breeds or deep-chested dogs. Both
of these are acute conditions, and can kill rapidly. Dogs are also
susceptible to parasites such as fleas
, as well as hookworms
, and heartworms
Dogs are highly susceptible to theobromine poisoning
from ingestion of chocolate
. Theobromine is toxic to dogs
because although the dog's metabolism is capable of breaking down
the chemical, the process is so slow that even small amounts of
chocolate can be fatal, especially dark chocolate.
Dogs are also vulnerable to some of the same health conditions
as humans, including diabetes
, dental and heart
disease, epilepsy, cancer, hypothyroidism, and arthritis.
Main article: Aging in dogs
The typical lifespan of dogs varies widely among breeds, but for
most the median longevity, the age at which half the dogs in a
population have died and half are still alive, ranges from 10 to 13
Individual dogs may live well beyond the median of their breed.
The longest-lived breeds, including Toy Poodles
, Japanese Spitz
, and Tibetan Spaniels
, have median
longevities of 14 to 15 years.
The median longevity of mixed breed dogs, taken as an average of
all sizes, is one or more years longer than that of purebred dogs
when all breeds are averaged.
The dog widely reported to be the longest-lived is "Bluey
," who died in 1939
and was claimed to be 29.5 years old at the time of his death;
however, the Bluey record is anecdotal and unverified.
The longest verified records are of dogs living for 24 years.
Although wild dogs, like wolves, are apex predators
, they can be killed in
territory disputes with wild animals.
Furthermore, in areas where both dogs and other large predators
live, dogs can be a major food source for big cats or canines.
Reports from Croatia indicate that dogs are killed more frequently
than sheep. Wolves in Russia apparently limit feral dog
populations. In Wisconsin, more compensation has been paid for dog
losses than livestock.
Some wolf pairs have been reported to prey on dogs by having one
wolf lure the dog out into heavy brush where the second animal
waits in ambush.
In some instances, wolves have displayed an uncharacteristic
fearlessness of humans and buildings when attacking dogs, to the
extent that they have to be beaten off or killed.
Coyotes and big cats have also been known to attack dogs. Leopards
in particular are known to have a predilection for dogs, and have
been recorded to kill and consume them regardless of the dog's size
Tigers in Manchuria, Indochina, Indonesia, and Malaysia, are
reputed to kill dogs with the same vigor as leopards.
Striped Hyenas are major predators of village dogs in Turkmenistan,
India, and the Caucasus.
Reptiles such as alligators and pythons have been known to kill and
Some sources describe dogs as carnivores
sources describe dogs as omnivores
, despite their descent from wolves
and despite their classification in the order Carnivora
Unlike an obligate carnivore
, such as a member of the
cat family with its shorter small intestine
, a dog is neither
dependent on meat-specific protein nor a very high level of protein
in order to fulfill its basic dietary requirements. Dogs are able
to healthily digest a variety of foods, including vegetables and
grains, and can consume a large proportion of these in their diet.
In the wild, canines often eat available plants and fruits.
In domestic dogs, sexual
begins to happen around age six to twelve months for
both males and females,
although this can be delayed until up to two years old for some
large breeds. This is the time at which female dogs will have their
. They will experience subsequent estrous cycles
biannually, during which the body prepares for pregnancy
. At the peak of the cycle, females
will come into estrus, being mentally and physically receptive to
Because the ova
survive and are
capable of being fertilized for a week after ovulation, it is
possible for a female to mate with more than one male.
Dogs bear their litters roughly 56 to 72 days after fertilization
an average of 63 days, although the length of gestation can vary.
An average litter consists of about six puppies
though this number may vary widely based on the breed of dog. Toy dogs
generally produce from
one to four puppies in each litter, while much larger breeds may
average as many as twelve.
Some dog breeds have acquired traits through selective breeding
that interfere with reproduction. Male French Bulldogs
, for instance, are
incapable of mounting the female. For many dogs of this breed, the
female must be artificially inseminated
order to reproduce.
According to the Humane Society of the
, 3–4 million dogs and cats are put down
each year in the
United States and many more are confined to cages in shelters
because there are many more animals than there are homes. Spaying
or castrating dogs helps keep overpopulation down.
humane societies, SPCAs, and other animal protection organizations
urge people to neuter their pets and to adopt animals from shelters
instead of purchasing them.
Neutering reduces problems caused by hypersexuality, especially
in male dogs.
Spayed female dogs are less likely to develop some forms of cancer,
affecting mammary glands, ovaries, and other reproductive
However, neutering increases the risk of urinary
in female dogs,
well as osteosarcoma, hemangiosarcoma, cruciate ligament rupture,
obesity, and diabetes mellitus in either gender.
is considered to be one of the most intelligent
The domestic dog has a predisposition to exhibit a social
intelligence that is uncommon in the animal world.
Dogs are capable of learning in a number of ways, such as through
) and by observation.
Dogs go through a series of stages of cognitive development.
They are not born with the understanding that objects which are not
being actively perceived still remain in existence, called object
. This occurs as the infant learns to interact
intentionally with objects around it. For dogs, this occurs at
roughly 8 weeks of age.
Puppies learn behaviors quickly by following examples set by
This form of intelligence is not peculiar to those tasks dogs have
been bred to perform, but can be generalized to myriad abstract
problems. For example, Dachshund puppies who watched an experienced
dog pull a cart by tugging on an attached piece of ribbon in order
to get a reward from inside the cart learned the task fifteen times
faster than those who were left to solve the problem on their
Dogs can also learn by mimicking human behaviors. In one study,
puppies were presented with a box, and shown that when a handler
pressed a lever, a ball would roll out of the box. The handler then
allowed the puppy to play with the ball, making it an intrinsic
reward. The pups were then allowed to interact with the box.
Roughly three-quarters of the puppies subsequently touched the
lever, and over half successfully released the ball, compared to
only 6 percent in a control group that did not watch the human
manipulate the lever.
Another study found that handing an object between experimenters
who then used the object's name in a sentence successfully taught
an observing dog each object's name, allowing the dog to
subsequently retrieve the item.
Dogs also demonstrate sophisticated social cognition
behavioral cues with abstract meanings.
One such class of social cognition involves the understanding that
others are conscious agents. Research has shown that dogs are
capable of interpreting subtle social cues, and appear to recognize
when a human or dog's attention is focused on them. To test this,
researchers devised a task in which a reward was hidden underneath
one of two buckets. The experimenter then attempted to communicate
with the dog to indicate the location of the reward by using a wide
range of signals: tapping the bucket, pointing to the bucket,
nodding to the bucket, or simply looking at the bucket.
The results showed that domestic dogs were better than chimpanzees
, wolves, and
human infants at this task, and even young puppies with limited
exposure to humans performed well.
, an expert on dog psychology, states that these results
demonstrated the social cognition of dogs can exceed that of even
our closest genetic relatives, and that this capacity is a recent
genetic acquisition which distinguishes the dog from its ancestor,
Studies have also investigated whether dogs engaged in partnered
play change their behavior depending on the attention-state of
Those studies showed that play signals were only sent when the dog
was holding the attention of its partner. If the partner was
distracted, the dog instead engaged in attention-getting behavior
before sending a play signal.
Dr. Coren has also argued that dogs demonstrate a sophisticated
theory of mind by engaging in deception, which he supports with a
number of anecdotes, including one example where a dog hid a stolen
treat by sitting on it until the rightful owner of the treat left
Although this could have been accidental, Coren suggests that the
thief understood that the treat's owner would be unable to find the
treat if it were out of view. Together, the empirical data and anecdotal
points to dogs possessing at least a limited form of
Main article: Dog behavior
Although dogs have been the subject of a great deal of behaviorist psychology
(e.g. Pavlov's dog
), they do not enter
the world with a psychological "blank slate".
Rather, dog behavior is affected by genetic factors as well as
Domestic dogs exhibit a number of behaviors and predispositions
that were inherited from wolves.
The Gray Wolf
is a social animal
has evolved a sophisticated means of communication and social
. The domestic dog has inherited some of these
predispositions, but many of the salient characteristics in dog
behavior have been largely shaped by selective breeding by humans.
Thus some of these characteristics, such as the dog's highly
developed social cognition
, are found only in
primitive forms in grey wolves.
Differences from wolves
Compared to equally sized wolves, dogs tend to have 20% smaller
skulls, 30% smaller brains
well as proportionately smaller teeth than other canid species.
Dogs require fewer calories to function than wolves. Their diet of
human refuse in antiquity made the large brains and jaw muscles
needed for hunting unnecessary. It is thought by certain experts
that the dog's limp ears are a result of atrophy
of the jaw muscles.
The skin of domestic dogs tends to be thicker than that of wolves,
with some Inuit
the former for use as clothing due to its greater resistance to
wear and tear in harsh weather.
The paws of a dog are half the size of those of a wolf, and their
tails tend to curl upwards, another trait not found in wolves.
Dogs tend to be poorer than wolves at observational learning
more responsive to instrumental conditioning
Feral dogs show little of the complex social structure or dominance
present in wolf packs. For dogs, other members of
their kind are of no help in locating food items, and are more like
Feral dogs are primarily scavengers, with studies showing that
unlike their wild cousins, they are poor ungulate
hunters, having little impact on
wildlife populations where they are sympatric
. However, feral dogs
have been reported to be effective hunters of reptiles in the Galápagos
and free ranging pet dogs are more prone to predatory behavior
toward wild animals.
Despite common belief, domestic dogs can be monogamous
Breeding in feral packs can be, but does not have to be restricted
to a dominant alpha pair (despite common belief, such things also
occur in wolf packs).
Male dogs are unusual among canids by the fact that they mostly
seem to play no role in raising their puppies, and do not kill the
young of other females to increase their own reproductive
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canid species by the fact that they do not regurgitate food for
their young, nor the young of other dogs in the same territory.
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for the young by the males has been observed in domestic dogs,
dingos as well as in other feral or semi-feral dogs. Regurgitating
of food by the females and direct choosing of only one mate has
been observed even in those semi-feral dogs of direct domestic dog
ancestry. Also regurgitating of food by males has been observed in
free-ranging domestic dogs.
Dogs display much greater tractability than tame wolves, and are
generally much more responsive to coercive techniques involving
fear, aversive stimuli, and force than wolves, which are most
responsive toward positive conditioning and rewards.
Unlike tame wolves, dogs tend to respond more to voice than hand
Although they are less difficult to control than wolves, they can
be comparatively more difficult to teach than a motivated wolf.
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