Dogs: Characteristics, Behavior and Intelligence | Early European History And Religion

Home | Category: First Modern Human Life / Life and Culture in Prehistoric Europe

DOGS

basenji, one of the oldest dog breeds All dogs (Canis lupus familiaris) descended from the gray wolf, the largest member of the Canidae family. Gray wolves are native to the northern hemisphere continental areas, including North America and Eurasia. Dogs and wolves are still capable of interbreeding. Wolf-dog crossbreeds are very unpredictable and potentially dangerous. One wolf-dog crossbreed heard a couch spring squeak and then tore up upholstery searching for a mouse.

Dogs and canids (wolf-like and dog-like animals) evolved from hesperocyons, predators that looked somewhat like jackals and lived 37 million years ago in North America. Dogs are believed to have been the first animals to be domesticated by ancient humans. Most archaeologists believe that dogs were first domesticated about 20,000 to 30,000 years ago. This was before the development of agriculture and permanent human settlements. There are currently about 400 million dogs in the world and 400,000 wolves. [Source: Xiaoming Wang and Richard Tedford, Natural History magazine, July-August 2008; Angus Phillips, National Geographic, January 2002]

If trained properly and treated well, dogs are loyal and protective animals. Domestic dogs have been bred to many purposes throughout the millenia, including as draft animals, guards, hunting, herding, and fishing aids, and as lap animals. More recently dogs are employed as guide dogs for the blind, deaf, and disabled, using their keen sense of smell to detect bombs or drugs, and as therapy animals. Because of their association with humans, domestic dogs are not preyed upon by wild predators. However, feral domestic dogs may be preyed upon by any large predator. Often they are killed by other canids, such as wolves and jackals. Domestic dogs carry and transmit human diseases, including viral, bacterial, and parasitic diseases. Dogs are still one of the primary vectors for transmitting rabies to humans in undeveloped parts of the world. In addition, domestic dogs are responsible for attacks on adults and children, sometimes resulting in death. [Source: Tanya Dewey and Sheetal Bhagat, Animal Diversity Web (ADW) /=]

The first dog to be cloned was an Afghan cloned in 2005 by South Korean researchers.

Canids, Canines and Canis

Canidae is a biological family of caniform carnivorans ("dog-like" carnivores). It constitutes a clade (group of organisms composed of a common ancestor and all of its descendants) Members of this family are called canids. The family includes three subfamilies: Caninae, and extinct Borophaginae and Hesperocyoninae. Caninae are known as canines,and include domestic dogs, wolves, coyotes, raccoon dogs, foxes, jackals, African wild dogs and other species. [Source: Wikipedia]

The Canidae family is comprised of 13 genera and 37 species. Canids are widely distributed around the globe. They occur on all continents except Antarctica and are only member of the Order Carnivora that found in Australia (we’re talking about dingoes, introduced by humans during prehistoric times). Canidae fossils have been dated to the to the Oligocene Period (33 million to 23.9 million years ago) and Miocene Period (23 million to 5.3 million years ago), which makes them among the oldest extant groups of carnivores. Canids are probably an early offshoot of the caniform lineage (which includes mustelids (weasels),procyonids (raccoons and their relatives), ursids (bears), phocids and otariids (seals), and odobenids (walruses).[Source: Bridget Fahey and Phil Myers, Animal Diversity Web (ADW)]

Canis encompasses "dog like" canids. It is a diverse genera encompassing seven species of canids which include jackals, wolves, coyotes, and domesticated dogs. Canis means "dog" in Latin, "canine tooth" is also derived from Canis and refers due to the long fang-like teeth that all canids possess. Previously the Canis included foxes but they were removed and separated into their own Vulpes genera. African wild dogs are canids but not canis. They are classified into the genus Lycaon and are the only surviving member of this genus.[Source: Lydia Oliver, Animal Diversity Web (ADW) |=|]

Variety of Dog Breeds

Shar Pei, another of the oldest dog breeds According to Pet Keen, there are between 195 and 500 different dog breeds, based on different organizations’ recognitions and experimental breeds. The American Kennel Club (AKC) dog breed list currently includes 200 dog breeds in the United States. The Complete Dog Breed Book described about 420 breeds of dogs. The oldest breed, the saluki, is thought to have emerged in 329 B.C. The most ancient dogs based on DNA evidence are the dingo, New Guinea singing dog, African basenji and greyhound.

Domestic dogs come in an amazing variety of sizes and shapes. They have been selectively bred for millenia for various behaviors, sensory capabilities, and physical attributes, including dogs bred for herding livestock (collies, sheperds, etc.), different kinds of hunting (pointers, hounds, etc.), catching rats (small terriers), guarding (mastiffs, chows), helping fishermen with nets (Newfoundlands, poodles), pulling loads (huskies, St. Bernard's), guarding carriages and horsemen (dalmatians), and as companion dogs. Some kinds were even bred simply as lap warmers (Pekingese). Their basic morphology though, no matter how modified, is that of their wild ancestors, gray wolves. [Source: Tanya Dewey and Sheetal Bhagat, Animal Diversity Web (ADW)]

The fact that dogs have 78 chromosomes (compared to 46 for humans) creates more opportunities for variation and enables these variations to develop relatively quickly. National Geographic described one man who wanted to develop a tail-less boxer. He crossed a boxer with a tail-less Welsh Corgi and took the tail-less offspring that looked most like boxers and mated them with other boxers. Eight years and four generations later he produced tail-less boxers that were winning show events.

Ancestors of Dogs

Xiaoming Wang and Richard H. Tedford wrote in “Dogs: Their Fossil Relatives and Evolutionary History”: “The downfall of the dinosaurs 66 million years ago gave mammals an incredible opening, and they ran for it, rapidly becoming the dominant land vertebrates. Among those to emerge were the earliest carnivorans (members of the order Carnivora), whose living representatives include the cats and closely allied families, such as hyenas and mongooses, as well as dogs and closely allied families, such as bears, weasels, and seals. As their name implies, most carnivorans eat meat, and even those that aren’t carnivorous—such as the giant panda—can be recognized. [Source: from “Dogs: Their Fossil Relatives and Evolutionary History,” by Xiaoming Wang and Richard H. Tedford, 2008 Columbia University Press, Natural History magazine, July-August 2008 ]

“A young adult Eucyon davisi, about the size of a living coyote, approaches one of its parents in a submissive attitude. The large social groupings in several species of the subfamily Caninae may have arisen when such youngsters remained in their parents’ territory and helped raise pups. The genus Eucyon lived in North America from about 9 million to 5 million years ago. by the last upper premolar and first lower molar on each side of the mouth. Those teeth are specially adapted for shearing, and are known as carnassials. Only in some species, such as seals and sea lions, have the carnassials evolved into simpler forms.

“Back when mammals got their big break—during the Paleocene epoch, which lasted ten million years—conditions around the globe were warm and humid. And the epoch that followed, the Eocene, was marked by a warming trend so great that even the polar regions were quite hospitable to life. Surging into prominence, flowering plants diversified and created lush forests all over the Earth. In North America, where tree canopies sheltered a growing number of primates and other forest-dwelling mammals, the earliest carnivorans arose. From there they spread to Eurasia, over land bridges that then existed to Europe or near the present-day Bering Strait. Mostly the size of small foxes, or smaller, the carnivorans were adapted to life in and around trees, probably preying on invertebrates and small vertebrates. They lived in the shadow of the generally much larger hyaenodonts, a group of mammalian predators that had come on the scene earlier but which later became extinct.”

Dog Characteristics

Dog range in weight from less than one kilogram to 70 kilograms (154 pounds). They are endothermic (use their metabolism to generate heat and regulate body temperature independent of the temperatures around them), warm-blooded (homoiothermic, having a constant body temperature, usually higher than the temperature of their surroundings) and have bilateral symmetry (both sides of the animal are the same) and are polymorphic (“many forms”, species in which individuals can be divided into easily recognized groups, based on structure, color, or other similar characteristics). Males are larger than females. [Source: Tanya Dewey and Sheetal Bhagat, Animal Diversity Web (ADW) /=]

All dogs have the same bones. The difference between the sizes and shapes of dogs is largely attributed to the fact that genes that affect the development of the fetus and puppy greatly alter a dog's final shape. The heads of puppies have different proportions than the heads of adult dogs and the way these proportions grow affect the way a dog looks. A greyhound, for example, has a long, slender snout because its nose starts growing early. A bulldog has short nose because the growth starts late.

All dogs have multicolored coats The lifespan of domestic dogs depends on the care they receive, their breed, and body size. In general, larger breeds have shorter lifespans. Well-cared for animals can live for 12 years or more. [Source: Max Planck Institute for Demographic Research]

Dogs have a slightly higher heart-to-body weight ratios than cats and other animals.,” Oyama says. The average weight of a dog heart is about 0.7 to 0.8 percent of their body weight, whereas in cats it's about 0.35 percent. [Source: Liz Langley, National Geographic, February 13, 2016]

Dog Behavior

All dogs wag their tails and have the ability to be trained. Dogs are diurnal (active during the daytime), nocturnal (active at night), motile (move around as opposed to being stationary), nomadic (move from place to place, generally within a well-defined range), territorial (defend an area within the home range), social (associates with others of its species; forms social groups), and have dominance hierarchies (ranking systems or pecking orders among members of a long-term social group, where dominance status affects access to resources or mates). Domestic dogs can be active at any time of the day or night. Feral domestic dogs maintain home ranges that they defend against others and may move around throughout the year. [Source: Tanya Dewey and Sheetal Bhagat,Animal Diversity Web (ADW) /=]

According to Animal Diversity Web: Domestic dogs are similar to their ancestors, wolves, in that they are both pack animals with a complex set of behaviors related to determining the dogs position in the social hierarchy and their mood. There is only one leader in a pack, and often there is a struggle between members of the pack to determine who the leader is. The struggle ends with one animal on top of the other, with the submissive animal lying on its back. The dominant animal places its paw on the chest of the submissive one, and until the submissive animal looks away from the eyes of the dominant animal, the struggle continues. As soon as the submissive animal averts his eyes, he has admitted defeat and the leader of the pack has been determined.

Dog Communication

Domestic dogs communicate and sense with vision, touch, sound and chemicals usually detected by smelling. They also employ pheromones (chemicals released into air or water that are detected by and responded to by other animals of the same species). They use a complex set of communication modes to navigate their social environment. Chemical cues, such as pheromones (chemicals released into air or water that are detected by and responded to by other animals of the same species), communicate information on reproductive status, social status, and mood. Body language is heavily used and various vocalizations are used as well. Social bonding and communication also occurs through touch. [Source: Tanya Dewey and Sheetal Bhagat, Animal Diversity Web (ADW) /=]

Dogs and wolves share similar behaviors and means of communications. Tail waging is a sign a friendship. Bowing is an invitation to play. When a dog lays on it back and exposing the stomach it is making itself vulnerable as a display of trust and affection. Licking is an expression of affection and submission. Wolf puppies lick their mothers to encourage them to regurgitate food. No one has come up with with a satisfactory answer to the question of why dogs bark.

Dogs express submission by lowering their body and head, tucking back their ears, diverting their eyes, and tucking their tail between the legs. Anger and aggression is expressed by holding the tail high, baring the teeth and staring directly ahead. After mating the male dog removes his forelegs from around the female's back but his penis often remains inside her. Sometimes the pair will remain stuck for a half an hour or more. This is because just before ejaculations the base of the penis swells into a bulb and is unable to withdraw.

According to Animal Diversity Web: Dogs exhibit characteristic postures that reveal their states of mind. The neutral position is when a dog is calmly observing things in the environment. The mouth of a dog in this position may be open or closed. In the alert position, the dog's mouth may be open or closed, depending on the excitement level and environmental temperature. The hairs along the back and shoulders may raise without any intent of the dog to attack. The dog has simply focused his attention on some object and is curious about it. Offensive threat posture: hair raised, teeth showing, nose wrinkled, and growling may be heard. The tail is upright, although it may be wagging. A dog in this stance is ready to attack. Defensive threat: although the dog may be growling and snarling, the ears are laid back, which is a sign of submission in normal dogs, and the tail is hanging down. Greetings: relaxed face, mouth slightly open, loosely pulled back ears, tail wagging. This is the posture dogs assume when playing with family members or other dogs. Play invitation: lowered front part of body while keeping the rear end up. A dog may bark in this invitation to play, but it does not growl excessively. Submission: body low to the ground, as compact as possible. Ears are drawn back, tail is tucked tightly under body. Submissive dogs pull the corners of their mouths back but do not show their teeth (submissive grin). Some submissive dogs assume the most vulnerable position known to dogs, lying on the backs, exposing their undersides. This position admits ultimate defeat in the struggle of dominance between dogs. /=\

Dog Mating, Reproduction and Offspring

Dogs are iteroparous. This means that offspring are produced in groups such as litters multiple times in successive annual or seasonal cycles. They engage in year-round breeding and are capable of reproducing every six months, though usually they do less frequently than that. [Source: Tanya Dewey and Sheetal Bhagat, Animal Diversity Web (ADW) /=]

The number of offspring ranges from one to 12, with the average number of offspring being 3-9, depending on the breed and nutritional status of the mother. The average gestation period is 63 days. Females and males reach sexual or reproductive maturity at six to 12 months. however, the time that a dog actually breeds depends on many social factors, ranging from size of breed (larger dogs need more time before they are ready to breed) and level of confidence a dog must attain before being ready to breed. Females nurse and care for their puppies until they are weaned at about eight to 10 weeks of age. In feral domestic dog packs, puppies are cared for by all members of the pack. /=\

Reproduction in domestic dogs is generally manipulated by humans. Feral males tend to compete amongst themselves for access to receptive females. Some feral domestic dog populations have reverted to ancestral habits where a single male and female pair (the alpha animals) dominate mating in a small, family group, or pack. Other pack members help to care for the offspring of the dominant pair.

Dog can be monogamous (having one mate at a time), cooperative breeders (helpers provide assistance in raising young that are not their own) and polygynandrous (promiscuous), with both males and females having multiple partners. Most breeds are seasonally monocyclic, showing signs of heat every six months or so. Dog are altricial. This means that young are born relatively underdeveloped and are unable to feed or care for themselves or move independently for a period of time after birth. Parental care is provided by both females and males. /=\

The reproductive cycle has four stages: 1) anestrus, 2) proestrus, 3) estrus, and 4) diestrus. The anestrus period lasts about two to four months. Proestrus is the time when a bloody discharge first appears in a female. This is the beginning of "heat," a period that usually last nine days but that can last up to 28 days. The end of this period is marked by the female's acceptance of a male partner. Estrus is the period when the female is sexually receptive and breeding can occur. Ovulation occurs about 24 hours after the acceptance of the male. Ova survive and are capable of being fertilized for about four days after ovulation; therefore it is possible for a female to mate with more that one male. Diestrus follows estrus in the nonpregnant cycle, characterized by a state of "pseudopregnancy", which is followed by a return of the uterus and ovaries to the anestrus, resting state. /=\

Dog Food and Eating Behavior

Dogs are primarily omnivores (eat a variety of things, including plants and animals). Animal foods include birds, mammals, amphibians, reptiles, fish eggs carrion insects terrestrial non-insect arthropods. Among the plant foods they eat are seeds, grains, and nuts fruit. [Source: Tanya Dewey and Sheetal Bhagat, Animal Diversity Web (ADW) /=]

According to Animal Diversity Web: Puppies have different feeding habits than older dogs. A puppy needs twice as much protein and 50 percent more calories per pound of body weight daily in order to meet its growth requirements. A rapid change in a puppy's diet may cause gastrointestinal upsets. Puppies must feed four times daily until the age of three months, three times daily until six months and twice daily for the rest of its life. Older dogs' feeding habits are different in a couple of ways. The average size dog requires about 30 calories per pound of body weight per day.

Interestingly, larger breeds need only 20 calories per pound of weight, while smaller breeds need about 40 calories per pound of body weight. A dog's diet should consist of balanced porportions of proteins, carbohydrates, fats and, of course, water. A dog can go days without food and lose 30 percent to 40 percent of it's body weight without dying, but a 10 percent to 15 percent water loss could be fatal. All-meat diets are not recommended for dogs due to the lack of calcium and iron found in meat. Diet supplements should be avoided. Human foods that can be fatal to dogs include moldy cheese, onions, and chocolate. Feral domestic dogs will eat a variety of foods including animals and fruits. /=\

Dog Intelligence

A border collie named Rico appeared in a German television game show in 2001. He knew the names of 200 toys and the easily up the names of new objects and was so smart researchers at the Max Planck Institute of Evolutionary Anthropology in Leipzig decided to study him. Their research showed that Rico could learn and remember words as quickly as a human toddler — which can acquire about 10 words a day. [Source: Virginia Morell, National Geographic, March 2008]

After checking out reports from hundreds of other dog owners that claimed their pets had advanced language abilities, only two — both border collies — were as clever as their owners claimed. One of them, a dog living in Vienna — which the researchers named Betsy — had a vocabulary of more than 340 words. She showed intelligence at an early age: at ten weeks she could sit on command and after that picked up object names such as a ball, paper, box, kety and rope, and dozens more. As of 2008 she knew 15 people by name and was able to link photographs with object pictured in the photographs. Her owner told National Geographic, “She’s a dog in a human [pack]. We’re learning her language , and she’s learning ours.”

Juliane Kaminski, a cognitive psychologist who worked with both Rico and Betsy, told National Geographic , “Even our closest relatives, the great apes, can’t do what Betsy can do — hear a word only once or twice and know that the acoustic pattern stands for something...maybe these collies are especially good at it because they’re working dogs and highly motivated, and in their traditional herding jobs, they must listen very closely to their owners.”

“Because dogs are so smart — and so trainable — there’s a whole range of assistance services they can be taught. There are dogs who help people with autism, Vanessa Woods of the Canine Cognition Center Woods at Yale says: “Dogs for PTSD, because they can go in and spot-check a room. They can turn the lights on. They can, if someone’s having really bad nightmares, embrace them so just to ground them. They can detect low blood sugar, alert for seizures, become hearing dogs so they can alert their owner if someone’s at the door, or if the telephone’s ringing.” [Source: Jeff MacGregor; Smithsonian magazine, December 2020]

“Canines demonstrate a remarkable versatility. “A whole range of incredibly flexible, cognitive tasks,” she says, “that these dogs do that you just can’t get a machine to do. You can get a machine to answer your phone — but you can’t get a machine to answer your phone, go do your laundry, hand you your credit card, and find your keys when you don’t know where they are.” Woods and I are on the way out of the main puppy office downstairs, where the staff and student volunteers gather to relax and rub puppy tummies between studies.

How Can Dogs Walk Barefoot in the Snow

Reuters reported: “Ever wonder how dogs can walk barefoot in the snow? Now a Japanese scientist may have the answer -- an internal central heating system. The secret lies in how dogs circulate their blood to prevent cold surfaces from chilling the rest of their bodies, according to Hiroyoshi Ninomiya, a professor at Yamazaki Gakuen University, just west of Tokyo. [Source: Reuters, February 27, 2012 /]

“The system uses warm, oxygenated blood to heat the cold blood that has been in contact with a cold surface before returning it to the dog’s heart and central circulation. “Dogs exchange heat at the end of their legs. Arterial blood flows to the end of their legs and then heats up venous blood before returning it to the heart,” Ninomiya said of his findings, published in the journal Veterinary Dermatology. “In other words, they have a heat exchange system in their feet.” /

“Ninomiya studied a preserved dog’s leg under an electron microscope and found that because of the proximity of arteries and veins in the foot pad, the heat in the blood carried from the heart to the arteries is easily conducted to the cooler blood in the veins. This heat transference maintains a constant temperature in the foot pad, even when exposed to extremely cold conditions. Dogs are not alone in having this sort of heat exchange system, which is shared by other animals such as dolphins, Ninomiya said. /

“But not all dogs thrive in the cold, due to refining by breeders seeking specific traits, he added. “Dogs evolved from wolves, and so they still have some of that ancestry remaining,” he said. “But that doesn’t mean that one should always go and drag around in the snow all the time. There are many varieties of dogs nowadays that are not able to stand the cold.” /

Dogs with Jobs

Jesse Ellison wrote in Newsweek: Among those in competition at the Westminster Dog Show in 2011 was Elias, a Beauceron who spends his time off the runway sniffing out gluten in food to protect people with celiac disease. And as scientists better understand the power of a dog’s nose — 100,000 times more sensitive than a human’s — canines are moving into other professions, too. [Source:J esse Ellison, Newsweek, February 13, 2011]

Doctors–Medical Techs: Labradors — Labs can detect colorectal and bowel cancer with 98 percent accuracy by examining stool samples, according to a recent study. The current technology is correct only 10 percent of the time.

Military Bomb Specialists: German Shepherds — Despite upwards of $20 billion spent on technology to detect roadside bombs, nothing beats a dog’s nose. Accordingly, there’s a major push to equip more soldiers with pups, especially in Afghanistan.

Pest Police: Jack Russell Terriers — Dogs can sniff out bedbugs with a 95 percent success rate, three times better than mere sight detection. So terriers, puggles, and other small breeds are increasingly in the employ of busy exterminators.

Deep-Sea Scientists: Rottweilers — Many breeds are used to help scientists track endangered species. One Rottweiler named Fargo worked aboard a boat looking for right whales — his broad chest gave him seaworthy balance.

Reality-TV Stars: Chihuahuas — Real Housewives meets Animal Planet: a new reality show called Doggie Moms follows five women and their pampered pooches. Can dogs out-Snooki the humans?

Image Sources: Wikimedia Commons

Text Sources: National Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Nature, Scientific American. Live Science, Discover magazine, Discovery News, Ancient Foods ancientfoods.wordpress.com ; Times of London, Natural History magazine, Archaeology magazine, The New Yorker, Time, Newsweek, BBC, The Guardian, Reuters, AP, AFP, Lonely Planet Guides, “World Religions” edited by Geoffrey Parrinder (Facts on File Publications, New York); “History of Warfare” by John Keegan (Vintage Books); “History of Art” by H.W. Janson (Prentice Hall, Englewood Cliffs, N.J.), Compton’s Encyclopedia and various books and other publications.

Last updated June 2024