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The monkeys in this photo reached adulthood at roughly age 7 or 8 (Poirier & Smith, 1974). Why do human preschoolers take twice as long to grow up?
The reason is that our species has a unique capacity—
What talent allowed humanity to mentally take off? Evolutionary theorists believe at the core of our achievements lies our social cognitive capacity to put ourselves in other people’s heads and decode intentions (recall Chapter 3). Monkeys show glimmers of this mindreading ability (see Buttelmann, Call, & Tomasello, 2009); but because they don’t have our language capacities (also described in Chapter 3), our close mammal cousins can’t draw on each other’s insights to transform the world. (“Oh, now I understand what you were trying to do. Let’s work together to improve on that.”) Capitalizing on these insights, in turn, demands a large, slow-
Actually, our huge cerebral cortex takes more than two full decades to mature. The myelin sheath—
Figure 5.1, which compares the size of our cortex to that of other species, shows the huge frontal lobes positioned at the top of the brain. During early childhood, the neurons in the visual and motor cortices are in their pruning phase, which explains why vision develops rapidly and why we master basic physical milestones, such as walking, at a relatively young age. However, the frontal lobes are only beginning their synaptic blossoming when we start toddling around. Pruning in this part of the brain will not start until about age 9.
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Their slow frontal-
In addition to allowing us to have the inner control to study (rather than watching TV) and the cognitive abilities to grasp long division, the frontal lobes are vital to mastering physical abilities, from tennis, to tightrope walking, to getting to the toilet at about age 3.
So, understanding that many regions of the brain work together to program every action and thought, let’s use our slow frontal-
In a sentence, explain why language is the core ability that makes human beings special.
Language is what really allows us to penetrate other minds—
When Steven played hide-
Ethan’s motor cortex is on an earlier developmental timetable than his frontal lobes.
If you learn that a colleague was in an accident and has frontal-
This is a disaster! Your colleague might have trouble with everything from regulating his physical responses, to analyzing problems, to inhibiting his actions.