I find via MindHacks that NYT Magazine has published a great article titled The Gregarious Brain, subtitled “Williams syndrome – a genetic accident that causes cognitive deficits-”. The writer, David Dobbs, does an spectacular job at explaining that syndrome in the context of what cognitive skills are and how they evolved. Some sample quotes:

• “In the view of two of Bellugi’s frequent collaborators, Albert Galaburda, a Harvard Medical School professor of neurology and neuroscience, and Allan Reiss, a neuroscientist at the Stanford School of Medicine, Nicki’s learned facility at sports talk illustrates a central lesson of Williams and, for that matter, modern genetics: genes (or their absence) do not hard-wire people for certain behaviors. There is no gene for understanding calculus. But genes do shape behavior and personality, and they do so by creating brain structures and functions that favor certain abilities and appetites more than others.”
• “…This doesn’t mean that specific behaviors are hard-wired. M.I.T. math majors aren’t born doing calculus, and people with Williams don’t enter life telling stories. As Allan Reiss put it: “It’s not just ‘genes make brain make behavior.’ You have environment and experience too. By environment, Reiss means less the atmosphere of a home or a school than the endless string of challenges and opportunities that life presents any person starting at birth.”
• (Talking about when our ancestors started to live in larger groups) “But the bigger groups imposed a new brain load: the members had to be smart enough to balance their individual needs with those of the pack. This meant cooperating and exercising some individual restraint. It also required understanding the behavior of other group members striving not only for safety and food but also access to mates. And it called for comprehending and managing one’s place in an ever-shifting array of alliances that members formed in order not to be isolated within the bigger group…The bigger an animal’s typical group size (20 or so for macaques, for instance, 50 or so for chimps), the larger the percentage of brain devoted to neocortex, the thin but critical outer layer that accounts for most of a primate’s cognitive abilities. In most mammals the neocortex accounts for 30 percent to 40 percent of brain volume. In the highly social primates it occupies about 50 percent to 65 percent. In humans, it’s 80 percent.” 
• “Generating and detecting deception and veiled meaning requires not just the recognition that people can be bad but a certain level of cognitive power that people with Williams typically lack. In particular it requires what psychologists call “theory of mind,” which is a clear concept of what another person is thinking and the recognition that the other person a) may see the world differently than you do and b) may actually be thinking something different from what he’s saying.”  

Enjoy the full article The Gregarious Brain.

You can learn more about cognitive skills and our ancestors at our recent post, titled Apes, Speedy Learners, and new Brain Fitness Channel, that shows the amazing abstract thinking skills of orangutans. Another related post on nature vs. nurture: Richard Dawkins and Alfred Nobel: beyond nature and nurture.