Razib Khan

July 15, 2009

Richard pointed me to a new study which suggests that domestic dogs exhibit an ability to understand human gestures at the level of a 2 year old. In contrast, chimpanzees are befuddled. Such comprehension is not trivial; infants are extremely good at manipulating and understanding adults, as any parent will tell you.  This particular finding is also not surprising, for several years ethologists have been reporting on the ability of domestic dogs to understand human facial expressions and manners. I stipulate domestic dogs because wolves, of which dogs are simply a specialized human-adapted morph, do not have these faculties. Like chimpanzees, wolves are more intelligent than domestic dogs. Domestics of all species are usually less intelligent than their wild forebears; after all, we do much of their thinking for them! The exceptions when it comes to relative dullness vis-a-vis wild canids are “working dogs,” such as border collies.

The take-home message here is that the mind is not an amorphous general mass. Rather, it exhibits domain-specific modularities. Language comes to mind immediately as a classic case and serves as a model for psychologists who wish to argue for massive modularity. The human ability to learn language quickly and easily is simply not an extension of our general intelligence. Those who lack this capability are pathologically deficient. In contrast, attempts to teach chimps and gorillas language suffer the problem that they seem unable to generalize syntax. This is not simply because of lack of intelligence; small children who are low in general intelligence have much greater powers in this domain than adult chimpanzees. Another example of a core human competency is facial recognition. Like language particular forms of brain damage can actually destroy the innate human ability to recognize faces immediately. It so happens that the ability to recognize humans visually is not restricted to humans, 90% of dogs are able to fix upon a photograph of their owner in a line-up. In contrast, only 50% of cats are able to complete this task.

This mosaic construction of our minds is almost certainly the result of the fact that evolution does not see beyond its nose. The problems which arise from this are documented entertainingly in Kluge, in which the cognitive psychologist Gary Marcus outlines the various deficiencies of our suboptimal solutions to evolutionary pressures. But I come not to bury evolution but praise it, as the example of the domestic dog shows the power of natural selection to reshape a lineage in the eyes of its owner. In short dogs are ideally adapted to the ecology of Homo sapiens. Not only do they exhibit mammalian neoteny, which seems to trigger normal reflexes of affection and playfulness, but despite atrophying in many of the skills necessary to survive in the wild they’ve developed abilities to comprehend the mentality of another species.

Just as evolution applies to dogs, it certainly applies to humans, as outlined in The 10,000 Year Explosion. Dogs differ in intelligence due to their niches, and so humans most certainly do as well. Just as dogs have different personalities whether they are obnoxious lapdogs or sedate working dogs, so do humans. And as humans are the ecology in which dogs have adapted, so humans are the ecology in which humans have adapted. Like environmental ecologies contingent upon the vicissitudes of climate and geology, human ecologies are always a shifting matrix of needs and demands. Arguably the most powerful selective force in the past 10,000 years has been malaria, which arose in Africa within the last 5,000 years, and slowly spread north into the Mediterranean. Naturally it is no surprise that even in the few generations which blacks have lived in North America that some of the adaptations to malaria which had negative consequences, such as sickle cell, have diminished in frequency. There is no end of evolution, rather it is a constant and eternal race, as per the Red Queen Hypothesis. On the one hand evolution can be ingenious, turning wolves into ideal pets and helpmates (and in the process dumbing them down too!). Yet on the other hand many of evolution’s short-term projects are slapdash affairs offered up in a take it or leave fashion. I would hazard to offer that this reality is most evident in lapdogs such as the Pekingese, whose bizarre morphologies and insufferable behavior cater to the tastes of the perverse. Truly nature knows no decency aside from the whims of fitness.