Genes, Brains, and Human Potential The Science and Ideology of Intelligence

266 HUMAN INTELLIGENCE

times bigger than the average for chimpanzees, even when body size is
taken into account.
As explained earlier in chapter  6, simple volume obscures a vast
increase in folding of the cortex to increase functional tissue volume. So
correlation between volume and function is not always clear. It seems rea-
sonable to suggest, though, that most of this enlargement is to support
the more complex cooperative lifestyle. Cooperative hunting on that scale
would require advanced cognitive skills at an individual level but also
ability to share epicognitive regulations at the group level. Cooperative
hunting would also demand intimate knowledge of the prey and their
typical be hav ior patterns, local and wider ecol ogy, terrain, predator risks,
weather patterns, and so on.
Th e new cognitive fl exibility is emphatically indicated in the surviv-
ing material culture of stone tools. Th e stone culture of Homo erectus and
the Neanderthals, over a period of a million years, tended to conform to
a ste reo typical pattern or style. Th e period from about seventy thousand
years ago, however, is marked by a spectacular creativity and variability
of styles. Th e culture includes complex bone technology; multiple-
component missile heads; perforated seashell ornaments; and complex,
abstract, and artistic designs. Th e distributions of this culture also suggest
trading between groups in which technological exchange accelerated cul-
tural development: the more contact there was between groups, the more
rapidly technology developed.^10 Th is is an impor tant additional layer in a
hierarchical dynamical system that would engender further creativity.

EVOLVED FOR COOPERATION

Th is, then, was the context for joint evolution of superb cognitive and
epicognitive systems, including the ge ne tic resources to support it and
the brain to house it. Human social cooperation was not a voluntary pro-
cess, in which a collection of “brainy” individuals chose to work together.
Instead, it emerged as a solution to stark environmental dynamics. In other
words, social cooperation was the context, not the result, of rapid cogni-
tive evolution. Th is has impor tant implications for understanding human
brains and cognition.

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