September 10, 2008
That’s the question asked, only partly tongue-in-cheek, by a 2008 review of studies in canine behavioral psychology (PDF) that comes to a startling conclusion: “[I]n many ways dogs are more human-like than any other species, including nonhuman primates.”
Dogs’ “human-like behaviors” include an uncanny ability to interpret
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“Of all creatures the one nearest to man in the fineneness of its perceptions and in its capacity to render true friendship is a bitch.”
—Konrad Lorenz |
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human body language, gaze, and other nonverbal cues, as well as to recognize as many as 200 words of human language. Their ability to “read” us exceeds that of either our closest genetic relatives (trained chimpanzees) or their own (tamed wolves), and there is evidence that the predisposition to do so is innate in dogs, not acquired anew through experience by each individual dog.
Here’s how the review’s authors, Monique A. R. Udell and C. D. L. Wynne of the University of Florida, put it:
[T]hough they share much less of our genetic material than do chimpanzees, [dogs] nonetheless show a spontaneous ability to follow human gestures to find reinforcing objects, even in the absence of training in the laboratory. Most remarkably, even dogs raised with minimal human contact can follow a human point and gaze gesture without explicit training. . . .
[C]himps and several other species of primates are only modestly successful on many tasks designed to test for human-like social reasoning. . . . [F]ew chimpanzees or other nonhuman primates are able to use gaze or other social cues such as pointing to identify the location of a hidden object. . . . [Amazing direct comparisons between dogs and chimps, which the dogs win paws down, can be read in full in one of the reviewed studies, Human-like social skills in dogs? (PDF) by Brian Hare and Michael Tomasello of the Max Planck Institute for Evolutionary Anthropology.]
[If] domestic dogs’ high sensitivity to social cues is an evolutionary legacy inherited from wolves, the dog’s closest wild relative and progenitor . . . then wolves also should do well on tasks involving social cues. However . . . domestic dogs (including puppies . . . that have had only minimal exposure to human beings) make significantly more correct responses . . . even though the wolves tested had been socialized and raised by humans in their homes as pets. Thus, it does not seem that . . . general social traits common to wild canids have simply been inherited by domestic dogs.
Hare and Tomasello make it clear that these skills are specifically social. Primates are much better at figuring out where hidden food is from non-social cues that require mental monkeying with objects, such as seeing one board lying flat and another one tilted up. The only other tested animal that “reads” gaze and body-language cues as well as or better than dogs is the human child.
(It’s fun reading articles on this subject because the scientists’ warm feelings for dogs keep breaking through the normally dry professional format. Udell and Wynne subtitle their review “Why Behavior Analysts Should Stop Worrying and Love Their Dogs.” Hare and Tomasello begin their closing summary, “It would seem that our canine companions have come to join in the human conversation in some unique and telling ways.”)
Clearly, this rapport that dogs share with humans must have been shaped by their domestication, their adaptation to the niche of the human household and our selection for the tendency to bond with and respond to us. But if wolves, even when raised by humans, do not possess these abilities, how did the wolf give rise to the dog, as genetic analysis confirms that it did? The naïve assumption that human tribes simply adopted orphaned wild wolf cubs and bred them in captivity doesn’t hold up, as one cutely pseudonymous Kayye Nynne writes:
Modern day wolf researchers are well aware that tame wolves behave nothing like dogs and retain many of the characteristics undesirable in a domesticated animal; namely independence and wariness of people.
When a tame wolf gives birth, it produces naturally wild offspring . . . in stark contrast to the offspring of dogs which are inherently tame right from the get go! If a wolf pup from a tamed individual is not socialized by humans before its eyes open that animal will have problems dealing with people; the same is not true of dogs even for much older puppies of several months! In other words, the taming of individual animals does not bestow genetic modification upon its offspring even over a span of many generations.
In an exhaustive, book-length doctoral dissertation (PDF) that’s available online, illustrated with the author’s own excellent dog photographs, Michelle J. Raisor provides a thorough overview of the behavior of wolves raised in captivity (starting on pp. 88, 234, and 262). (Her thesis also manages to cram in molecular genetics, the canine genome, controversies in canid evolution and systematics, and fossil dog finds from all over the world.) Raisor makes a convincing case that wolf pups have ingrained tendencies toward both fearfulness and (as they get older) aggressiveness that would have made Canis lupus awfully hard to start domesticating.
[One experimenter found that] wolf pups litter raised by their wolf mother exhibited flight behavior by 21 days old and never became socialized with humans. . . . [Another research team] obtained 11-day-old wolf pups which they felt would better bond to their human caregivers. The researchers spent approximately 12 hours per day with the wolves during which time they were bottle-fed and alternately spent nights with the authors or wolf mother. . . . [The] wolf pups continued to have a tenuous relationship with the human. . . . As [they] grew, they still exhibited a distinct preference for canine social partners, rather than their human caregivers. . . . [E]ven those pups that were raised by [a] friendly, socialized mother remained non-social and shy.
“The readiness of dogs to look at the human face” has been key to “the development of complex forms of dog-human communication.” By contrast, wolves are compelled to look away from the human gaze:
Clearly if early man attempted to tame wolves it would have been necessary for them to recognize the wolves’ behavioral responses in order to assimilate a wild animal into the human social structure. Early man would have had to be cognizant of his own reflexive reactions that would provoke an attack. For example, smiling or any display of the teeth could be interpreted by a wolf as a challenge for dominance and lead to an attack. The same is true for eye-to-eye contact between a wolf and human. Although a submissive animal would flee when gazed at, an aggressive wolf would view this as a threat and could possibly launch a violent attack.
Add the great difficulty of weaning wolf pups to a solid diet. Can you imagine a hard-pressed Pleistocene family going to so much trouble for so little reward?
Raisor’s conclusion:
I suggest that dogs were dogs long before man even considered the possibility of [adopting and selectively breeding them]. . . . [G]enetically different animals [evolved that] were not the product of domestication, but rather a new adaptation to a changing environment. . . . [a] natural evolutionary divergence that occurred without human intervention.
And yet, the big change in the natural environment to which this new creature, Canis familiaris, would have been an adaptation was very probably . . . the presence of humans! Or even of pre-sapiens hominids: bones of small wolves have been found “in association with” those of cave-dwelling Homo erectus near Beijing, China, dating from 460,000 to 230,000 years ago. And genetic evidence points to East Asia as the cradle of the dog.
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