Middle Eastern Origin of Dogs Argued in New Genome Study

A study of the dog genome published in Nature, the pre-eminent publication in biology, reached some surprising and immediately controversial results. For one, disagreeing with prior studies, the new research concludes that “dog breeds share a higher proportion of multi-locus haplotypes unique to grey wolves from the Middle East….” (vonHoldt et al., Genome-wide SNP and Haplotype Analyses Reveal a Rich History Underying Dog Domestication, Nature, vol. 464(8), April 2010). This takes issue with mitochondrial DNA studies that suggested that canine domestication first occurred in east Asia (see Savolainen et al., Science vol. 298, 1610-1613, 2002).

The new research does accept that interbreeding with local wolf populations “clearly occurred elsewhere in the early history of specific lineages.” The researchers sampled 912 dogs from 85 breeds, as well as taking samples from 225 grey wolves from 11 populations around the world. Certain breeds were found to have demonstrated admixture with wolves, particularly breeds with ancient origins that are highly divergent from other dog breeds. Breeds in this group include, not surprisingly, Akitas, Alaskan malamutes, Siberian huskies, and American Eskimo dogs. However, wolf admixture is also found in basenjis, Afghan hounds, Samoyeds, salukis, Canaan dogs, New Guinea singing dogs, dingoes, Chow chows, and Chinese Shar Peis. Some breeds share more with Chinese wolves, some with European wolves, and some with Middle Eastern wolves. Akitas, for instance, show admixture with Chinese wolves, Staffordshire bull terriers with Northern wolves, and basenjis with Middle Eastern wolves. In some cases, the admixture must have been ancient. Dingoes have been isolated from any wolf population for perhaps 4,000 years.

Towards the end of the paper, the researches say that “some ancient east Asian breeds show affinity with Chinese wolves, which suggests that they were derived from Chinese wolves or admixed with them after domestication." This challenges the assumption that has prevailed for some years that dogs were domesticated only once, and harks back to Darwin and others who suggested that canine domestication may have occurred more than once from different populations of canids. The researchers also note that wolves have changed as a result of dogs. The mutation responsible for black coat color was transferred from dogs to grey wolves.

The researchers found “distinct genetic clusters” even within modern dogs based on phenotype and function, including spaniels, scent hounds, mastiff-like breeds, small terriers, retrievers, herding dogs, and sight hounds. Scent hounds include Basset hounds, beagles, and dachshunds. The research behind this six-page paper (supplementary information of 38 pages) is probably only the beginning of a series of papers one can expect from these 36 authors. That’s right! 36 authors.

Supplemental note. I received a comment arguing that American Eskimo dogs do not belong in the category of ancient breeds that show admixture with wolves. The supplemental information to the paper in Nature lists three somewhat distinct groups of dogs in this category. The first consists of basenjis, Afghan hounds, Samoyeds, Salukis, and Canaan dogs. The second consists of New Guinea singing dogs, dingoes, Chow chows, Shar peis, and Akitas. The third consists of Alaskan malamutes, Siberian huskies and American Eskimo dogs. Looking at Supplemental Figure 1, the research indicates that the first group demonstrates significant gene sharing with Middle Eastern wolves, the second group with Chinese wolves, and the third group with Northern wolves. The Inuit Sled Dog (sometimes confused with the American Eskimo dog) is generally thought of as an ancient breed, but the American Eskimo Dog is described by the American Kennel Club as a member of the Spitz family related to the spitz breeds and the white Pomeranian. See Sue Hamilton, "Replica or the Real Deal," The Fan Hitch 4(3) (May 2002). The Nature article does, however, list "Ancient and spitz breeds" as one category so I have to assume, until I hear from one of the Nature article's authors, that they do in fact mean the American Eskimo dog.

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Owning Both a Dog and a Cat: Start Them Young

We have been expecting them to get along for perhaps thousands of years. An Italian woodcut from 1549 shows two dogs and a cat waiting for scraps to fall, or be thrown, from a table (Banchetti Compositioni di Vivende, 1549).  The second picture is the left section of Pietro Lorenzetti's Last Supper in Assisi (c. 1520).

Two scientists at Tel Aviv University recently applied some scientific approaches to looking at the interactions of dogs and cats living in the same households. Neta-li Feuerstein and Joseph Terkel, Interrelationships of Dogs (Canis familiaris) and Cats (Felis catus L.) Living under the Same Roof, Applied Animal Behaviour Science, 113, 150-165 (2008). Feuerstein and Terkel note that both species were attracted by the presence of food in human settlements. Cats served as controllers of vermin in grain supplies, and though this may have begun in Egypt, the oldest evidence of a domesticated cat comes from Cyprus around 9,500 years ago. These authors accept an older date for the emergence of the dog, somewhere between 35,000 and 100,000 years ago. They accept that cats are at an earlier phase of domestication than dogs.

Dogs and cats both belong to the order Carnivora, but their social behavior is quite different. Dogs live and hunt in packs, but cats are mostly solitary hunters. Feuerstein and Terkel conducted their research through questionnaires and observations in the homes of individuals having both species as pets. They hypothesized that an early age of adoption would make things smoother, and that early adoption would also increase the amount of understanding the member of one species might have of the body cues of the other. Direct observations included using fixed situations such as rolling a ball between a dog and a cat to determine whether mutual play would occur, and to observe any dominant behavior. Cat food was placed between the dog and the cat to see what this would bring about. Cat food was used because dogs like the high protein content of cat food.

The researchers noted that certain behaviors had different meanings for each species. Stretching out the forefeet is, for a dog, a sign of amicability and submission, but for the cat it is an aggressive behavior. Lying on the back is submissive for a dog, but aggressive for a cat. Moving the head away is submissive for a dog, but aggressive and dominant for a cat, and horizontal tail wagging is amicable and submissive for a dog, but aggressive and even a hunting posture for a cat.

Dominance behavior patterns of the cat include direct stare, pricked ears, and jumping to a high place (higher than the dog). Aggressive behavior patterns of cats include:

• Growl
• Hiss or spit
• Piloerection (along the back, tail, or both), whiskers may also be directed
• Extracted claws
• Thrashing tail
• Arching the back and tail (creating an inverted U shape of the tail)
• Raised fore-leg
• Attack (lunge, using fore-legs, claws extracted)
• Flattened ears (pointing backwards)
• Lying on the back
• Averted gaze (with enlarged pupils)

Fear and submission behavior patters of cats include:

• Ears turned backwards
• Excessive salivation
• Backing away
• Crouched walk (lowered back, close to the floor)
• Sideways movement
• Tail flattened to the body (sometimes between the hind legs)
• Retreating (to occupy a position as far as possible from the dog
• Grooming (licking and grooming the body)
• Head shake (from side to side)

Play behavior patterns of cats include chirping, purring, kneading (with sheathed claws), moving the tip of the tail, rolling on the ground, and licking the dog’s face or body. For dogs, dominance behavior patterns include tail raised above the level of the back, direct stare, standing tall or stiff walking, pricked ears, lips pooled forward, barking, moving over the cat. Aggressive behavior patters include wrinkled on the upper part of the shout, bared teeth, hackles raised between shoulders and tail, growling, and attacking. Fear and submissive behavior patters include:

• Averted gaze
• Lowered tail
• Crouching walk or posture
• Lying on the back
• Flattened ears
• Lips retracted
• High pitched whine
• High pitched bark
• Backing away
• Yawn
• Licking lips
• Blinking
• Retreating

Play behavior patters include the play bow, play growl, chasing, lying on the back, biting, licking motion in the air or on the cat’s body, and play face (relaxed, lips retracted, ears falling downwards).

The researchers found that cats performed significantly more play behavior and fear or submission towards the dog than the other way around. Female cats exhibited a higher level of both aggression and indifference to the dogs compared with male cats, and a lower level of amicability towards the dogs. Neutered female cats were more often afraid of dogs than intact females. Dogs were found to be more friendly to cats if the dogs if the cat came first in the home. With cats it did not matter which came first. Dogs were less aggressive if they encountered the cats before the dogs were a year old. With cats, they were more friendly if they encountered the dogs before being six months old. In other words, cats lose their ability to adapt to dogs at an earlier age than is true of dogs with respect to cats.

As to the four behaviors in the table above which have opposite meanings for the species, the authors found that the animals read the meaning of the other species “significantly correctly.” They believe that the longer period of adaptability in dogs reflects the fact that dogs, descended from wolves, must develop collaborative hunting skills over a longer period of time, whereas cats become solitary hunters and do not need such social skills.

The authors argue that through adding a dog to a house with a cat, “the cat’s quality of life can be improved.” I would have to note that our cat, Jack, would very much disagree. Jack was ten years old when we adopted Chloe. He had spent most of his life in a coop apartment in Brooklyn Heights that allowed cats, but not dogs (cats don’t have to go into common areas very often). We could only adopt a dog when we moved out of the building. Jack has never taken to Chloe, though he has over time gained the upper hand. She stays clear of him, and he hisses if she gets near. He has become a mean cat, probably reflecting his feeling that things were just fine before she arrived. They have never played together, though Chloe spent years trying to accomplish that. Everyone’s experience is different.

The war between dogs and cats has been a source of wonder, and often amusement, though history. The last panel from a reconstructed Egyptian wall painting, dating from soon after the domestication of cats, shows the mouse pharoah and his army attacking the cat fortress. The dogs aid the mice by pulling pharoah's chariot. Since the mice seem to be winning, it must be assumed that the current pharoah was a dog person (or a mouse person). A. Erman (1894) Life in Ancient Egypt, p. 520. Macmillan & Co. London.

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Why Do Dogs Respond to Our Social Cues?

A focus of research on dog behavior has concerned the ability of dogs to respond to our social cues. In object choice tasks, a dog will have to decide which of two or more containers contains food. With certain controls, the dog unaided by a human will only perform at chance levels. If, however, a human points to the correct container, the dogs will much more likely go to it than the others. Even a human moving his eyes from the dog to the correct container and back and forth in this manner will help the dogs make the right choice, though not as often as pointing. Dogs will also choose the container a human is pointing at even if this is the wrong container, they’ve had a chance to smell the container with the food, and their noses should tell them to ignore the human’s pointing gesture. They trust us even when they shouldn’t. These findings, long known among canine behaviorists, lead to another question. Why do they follow our gestures when other animals, such as apes, don’t? Do they know we are trying to help them? Have they learned to trust us in the process of domestication? Pamela J. Reid of the ASPCA’s Animal Behavior Center in Urbana, Illinois, recently reviewed the literature on this topic, looking at the various hypotheses that have been propounded to explain why dogs read us so well. She distilled the conclusions of prior researchers down to four basic theories:

1. Dogs learn to respond to human social cues through basic conditioning processes.
2. Dogs reduced their fear of humans in the process of domestication and began to apply all-purpose problem-solving skills to their interactions with people.
3. Dogs’ co-evolution with humans equipped them with the cognitive machinery to respond to human social cues and understand our mental states (sometimes called a “theory of mind”).
4. Dogs are adaptively predisposed to learn about human communication gestures.

Reid herself favors the fourth explanation.

As to the first of the four theories, Reid notes that although dogs respond better to social cues after training, they perform significantly above chance even without prior experience with a pointing cue. Wolves raised the same way as dogs will not succeed as well as dogs in responding to pointing gestures.

Some researchers have argued that selection pressures placed on dogs for tameness and other desirable traits may have also been a stimulus for dogs to develop a specialized set of social skills. Dogs have learned to eat in the presence of humans and to accept restraint and in the process of domestication became expert readers of human social cues. Most (but not all) studies have found that dogs respond to social cues from humans far better than do wolves, their undomesticated ancestors. (Contrary research has recently been published by Monique Udell of the University of Florida and her colleagues.) Reid notes that Belyaev’s foxes, domesticated artificially, can follow pointing gestures as well as dog puppies of the same age, and are better at it than wild foxes. New Guinea Singing Dogs, similar to Australian dingoes, also perform of above chance, indicating that the ability to respond to human cues probably began in the earliest phases of domestication, since these unique dogs had only a rudimentary level of domestication before losing human contact. Perhaps dogs have learned to apply general rules of thumb such as “always approach the closest extension of the person,” or “always approach the person’s movement.” Such a mechanism would generally lead to the correct container in object choice tasks where a piece of food is placed in one of two or three containers and a human points to the correct container.

Reid attributes the third theory on the list above to the work of Adam Miklosi and Jozsef Topal and their colleagues, who argue that dogs and humans have evolved together to such an extent that human-like social skills have materialized in the dog in a process sometimes termed convergent evolution. This comes close to arguing that a dog understands that the human is trying to convey the location of food with a gesture. Miklosi has shown that dogs faced with an insoluble problem will look at a nearby human as though soliciting assistance. Reid argues that those scientists that take this “theory of mind” approach have found more sophisticated cognition in dogs than is justified by their research. It is, of course, likely that most pet owners would prefer to believe that there is a high level of human understanding in their pets.

Reid thinks the answer lies in the biological status of the dog as a scavenger, a niche that requires that an animal be acutely aware of other individuals in the social group that are also looking for opportunities to scrounge. They respond to our gestures towards food sources just as they respond to the other members of a pack that may be on the trail of a food source. This skill, combined with a tendency to learn, provided dogs with the skill to respond appropriately to our gestures, she argues. Reid admits that further research will be needed to narrow down the possible explanations as to why dogs are able to respond to our social cues. Pamela J. Reid, “Adapting to the Human World: Dogs’ Responsiveness to Our Social Cues,” 80 Behavioural Processes 325-333 (2009).

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