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Humanity is carried on the voice
By Nicholas Epley – Hard-thinking people have spent millennia trying to articulate what distinguishes us from all other creatures. Is it having opposable thumbs? Walking upright? Using tools? Thinking analytically? This question finally got a fairly clear answer several years ago thanks to researchers at the Max Planck Institute for Evolutionary Anthropology, in Germany, who brought in 105 human two-year-olds in order to compare their intellectual performance on essentially two different measures of IQ with that of 106 chimpanzees and, just for good measure, another 36 orangutans.

In tests that required reasoning about physical objects—things such as being able to track where a reward is placed under a cup, or being able to use a tool to solve a problem—the toddlers were basically neck and neck with the other primates in their performance. But in tasks where some social intelligence was involved, where subjects had to be able to track what was going on in someone else’s mind and respond accordingly—such as following the path of someone’s gaze, or understanding what someone was intending (but failed) to do—the human toddlers crushed the competition.

It makes sense that we’re good at this sort of social thinking: we are literally built for it. Our human brain stands out in the animal kingdom for its relatively gigantic neocortex—the fat part just above your eyes. What’s all that neural capacity good for? Lots and lots of things, but what it really seems to be designated for is social stuff.

If you look across primate species, what you see is that the size of the neocortex relative to the rest of the brain is positively correlated with the size of the social group that primate species inhabits. The larger the social group, the larger the neocortex relative to the rest of the brain. Human beings are the most social of all primates, and we also have the largest neocortex relative to the rest of the brain.

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Living in large social groups requires having a tremendous amount of neural capacity to keep track of who knows what, who believes what, who likes what, who should be trusted and who should be avoided, and so on. Living in large social groups is also easier if you have some capacity to anticipate others’ actions before they make them, meaning that the ability to interpret somebody’s behavior in terms of an underlying mental state or goal is also invaluable. It’s our social intellect, not our thumbs, or our posture, or anything else, that makes human beings so special. more>


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