History of dog

Behaviour

 Dogs tend to be poorer than wolves and coyotes at observational learning, being more responsive to instrumental conditioning.[3] Feral dogs show little of the complex social structure or dominance hierarchy present in wolf packs. For dogs, other members of their kind are of no help in locating food items, and are more like competitors.[3] 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. Free ranging pet dogs however are more prone to predatory behaviour toward wild animals. Feral dogs have been reported to be effective hunters of reptiles in the Galapagos islands Despite common belief, domestic dogs can be monogamous.[29] 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 success.[28] Some sources say that dogs differ from wolves and most other large canid species by the fact that they do not regurgitate food for their young, nor the young of other dogs in the same territory. 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 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.

Trainibility

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.[32] Unlike tame wolves, dogs tend to respond more to voice than hand signals.[33] Although they are less difficult to control than wolves, they can be comparatively more difficult to teach than a motivated wolf.

Main article: Dog anatomy. See also: Dog health

Modern dog breeds show more variation in size, appearance, and behavior than any other domestic animal. Within the range of extremes, dogs generally share attributes with their wild ancestors, the wolves. Dogs are predators and scavengers, possessing sharp teeth and strong jaws for attacking, holding, and tearing their food. Although selective breeding has changed the appearance of many breeds, all dogs retain basic traits from their distant ancestors. Like many other predatory mammals, the dog has powerful muscles, fused wristbones, a cardiovascular system that supports both sprinting and endurance, and teeth for catching and tearing. Dogs are more variable in size than any other domesticated animal. The smallest known dog was a Yorkshire Terrier, who stood only 6.3 cm (2.5 in) at the shoulder, 9.5 cm (3.75 in) along the head-and-body length and weighed only 113 grams (4 ounces). The largest known dog was an English Mastiff which weighed 155.6 kg (343 lbs) and was 250 cm (8.2 feet) from the snout to the tail. The tallest dog is a Great Dane that stands 106.7 cm (42.2 in) at the shoulder.

Sight

A Greyhound, one of many breeds of sighthoundLike most mammals, dogs are dichromats and have color vision equivalent to red-green color blindness in humans. Different breeds of dogs have different eye shapes and dimensions, and they also have different retina configurations. Dogs with long noses have a "visual streak" which runs across the width of the retina and gives them a very wide field of excellent vision, while those with short noses 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. Some breeds, particularly the sighthounds, have a field of vision up to 270° (compared to 180° for humans), although broad-headed breeds with short noses have a much narrower field of vision, as low as 180°.

Hearing

According to hypertextbook.com, the frequency range of dog hearing is approximately 40 Hz to 60,000 Hz.[39] Dogs detect sounds as low as the 16 to 20 Hz frequency range (compared to 20 to 70 Hz for humans) and above 45 kHz[40] (compared to 13 to 20 kHz for humans), and in addition have a degree of ear mobility that helps them to rapidly pinpoint the exact location of a sound.[41] Eighteen or more muscles can tilt, rotate and raise or lower a dog's ear. Additionally, a dog can identify a sound's location much faster than a human can, as well as hear sounds up to four times the distance that humans are able to.[41] Those with more natural ear shapes, like those of wild canids like the generally hear better than those with the floppier ears of many domesticated species.

Smell

Scent hounds, especially the Bloodhound, are bred for their keen sense of smell.[42]Dogs have nearly 220 million smell-sensitive cells over an area about the size of a pocket handkerchief (compared to 5 million over an area the size of a postage stamp for humans). According to nhm.org, dogs can sense odors at concentrations nearly 100 million times lower than humans can. According to Dummies.com, the percentage of the dog's brain that is devoted to analyzing smells is actually 40 times larger than that of a human.[43] Some dog breeds have been selectively bred for excellence in detecting scents, even compared to their canine brethren. The highly sensitive nose of a dog.

Coat color

Domestic dogs often display the remnants of counter-shading, a common natural camouflage pattern. The general theory of countershading is that an animal that is lit from above will appear lighter on its upper half and darker on its lower half where it will usually be in its own shade. This is a pattern that predators can learn to watch for. A countershaded animal will have dark coloring on its upper surfaces and light coloring below.[46] This reduces the general visibility of the animal. One reminder of this pattern is that many breeds will have the occasional "blaze", stripe, or "star" of white fur on their chest or undersides.

Tail

There are many different shapes for dog tails: straight, straight up, sickle, curled, cork-screw. In some breeds, the tail is traditionally docked to avoid injuries (especially for hunting dogs). It can happen that some puppies are born with a short tail or no tail in some breeds.

Behavior and intelligence

Further information: Category:Dog training and behavior. Many dogs, such as this American Water Spaniel, have had their natural hunting instincts suppressed or altered to suit human needs. Many dogs can be trained to skillfully perform tasks not natural to canines, such as in this dog agility competition.Dogs are very social animals, but their personality and behavior vary with breed as well as how they are treated by their owners and others who come in contact with them. It is not uncommon for dogs to attack humans and other animals; however, this is usually because of lack of care or improperupbringing by its owner.

Intelligence

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Main article: Dog intelligence

Dogs are valued for their intelligence. This intelligence is expressed differently with different breeds and individuals, however. For example, Border Collies are noted for their ability to learn commands, while other breeds may not be so motivated towards obedience, but instead show their cleverness in devising ways to steal food or escape from a yard. Being highly adaptable animals themselves, dogs have learned to do many jobs as required by humans over the generations. Dogs are employed in various roles across the globe, proving invaluable assets in areas such as search-and-rescue; law enforcement (including attack dogs, sniffer dogs and tracking dogs); guards for livestock, people or property; herding; Arctic exploration sled-pullers; guiding the blind and acting as a pair of ears for the deaf; assisting with hunting, and a great many other roles which they may be trained to assume. Most dogs rarely have to deal with complex tasks and are unlikely to learn relatively complicated activities (such as opening doors) unaided. Some dogs (such as guide dogs for the visually impaired) are specially trained to recognize and avoid dangerous situations.

Evaluation of a dog's intelligence

The meaning of "intelligence" in general, not only in reference to dogs, is hard to define. Some tests measure problem-solving abilities and others test the ability to learn in comparison to others of the same age. Defining it for dogs is just as difficult. It is likely that dogs do not have the ability to premeditate an action to solve a problem. A mirror test is one possible measure of self-awareness.For example, the ability to learn quickly could be a sign of intelligence. Conversely it could be interpreted as a sign of a desire to please. In contrast, some dogs who do not learn very quickly may have other talents. An example is breeds that are not particularly interested in pleasing their owners, such as Siberian Huskies. Huskies are often fascinated with the myriad of possibilities for escaping from yards, catching small animals, and often figuring out on their own numerous inventive ways of doing both. Many owners of livestock guardian breeds believe that breeds like the Great Pyrenees or the Kuvasz are not easily trained because their stubborn nature prevents them from seeing the point of such commands as “sit” or “down”. Hounds may also suffer from this type of ranking. These dogs are bred to have more of a "pack" mentality with other dogs and less reliance on a master's direct commands. While they may not have the same kind of intelligence as a Border Collie, they were not bred to learn and obey commands quickly, but to think for themselveswhile trailing game.

Human relationships

A U.S. Army Staff Sgt. and his military working dog wait at a safe house before conducting an assault against insurgents in Buhriz, Iraq on April 10, 2007.Dogs are highly social animals. This can account for their trainability, playfulness, and ability to fit into human households and social situations. These attributes have earned dogs a unique position in the realm of interspecies relationships despite being one of the most effective, voracious, and potentially dangerous predators. Dogs and humans at times co-operate in some of the most effective hunting in the animal world; on that context, dogs are superpredators. Barking can be used as a form of communication amongst dogs.The loyalty and devotion that dogs demonstrate as part of their natural instincts as pack animals closely mimics the human idea of love and friendship, leading many dog owners to view their pets as full-fledged family members. Conversely, dogs seem to view their human companions as members of their pack, and make few, if any, distinctions between their owners and fellow dogs. Dogs fill a variety of roles in human society and are often trained as working dogs. For dogs that do not have traditional jobs, a wide range of dog sports provide the opportunity to exhibit their natural skills. In many countries, the most common and perhaps most important role of dogs is as companions. Dogs have lived and worked with humans in so many roles that their loyalty has earned them the unique sobriquet "man's best friend", a term which is used in other languages as well as in Icelandic (“besti vinur mannsins”). However, some cultures consider dogs to be unclean. In some parts of the world, dogs are raised as livestock to produce dog meat for human consumption. In many places, consumption of dog meat is discouraged by social convention or cultural taboo.

Dog communication

Dog communication refers to body movements and sounds dogs use to send signals to other dogs, and other animals (usually humans). Dog communication comes in a variety of forms. Dogs use certain movements of their bodies and body parts and different vocalizations to send signals. There are a number of basic ways a dog can communicate. These are movements of the ears, eyes and eyebrows, mouth, head, tail, and entire body, as well as barks, growls, whines and whimpers, and howls.

Reproduction

Dogs develop their own societies. Puppies participate with their littermates in learning to relate to other dogs. Dogs learn to successfully relate to other dogs by keeping the peace, rather than by constantly fighting to reestablish this hierarchy.

Life cycle

Main article: Canine reproduction

In domestic dogs, sexual maturity (puberty) begins to happen around age 6 to 12 months for both males and females,[51] although this can be delayed until up to two years old for some large breeds. Adolescence for most domestic dogs is around 12 to 15 months, beyond which they are for the most part more adult than puppy. As with other domesticated species, domestication has selectively bred for higher libido and earlier and more frequent breeding cycles in dogs, than in their wild ancestors. Dogs remain reproductively active until old age. An Australian Shepherd Puppy Red MerleMost female dogs have their first estrous cycle between 6 and 12 months, although some larger breeds delay until as late as 2 years. Females experience estrous cycles biannually, during which her body prepares for pregnancy, and at the peak she will come into estrus, during which time she will be mentally and physically receptive to copulation. Dogs bear their litters roughly 56 to 72 days after fertilization,[52] with an average of 63 days, although the length of gestation can vary. An average litter consists of about six puppies,[53] 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 12 pups in each litter.

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