POTENTIAL BETWEEN BRAINS 251cognitive regulatory networks as well as cognitive networks alone. It is
also well known that domestication in any species drastically reduces
brain size over generations, indicating eff ects of ecol ogy and lifestyle.
However, an impor tant point is that there may have been an evolution-
ary limit to further brain expansion in quadrupeds, because a horizon-
tally extended neck would have been unable to bear the greater weight of a
bigger brain in a bigger skull. Of course, many quadrupeds manage to
carry large horns or other protuberances on their skulls. But they are not
the species engaged in social hunting. It may be that further evolution
awaited the emergence of a bipedal (upright) gait, as described in chapter 9.
PRIMATES AND “ FREE MARKET ECONOMICS”Th e primates (monkeys and apes) are usually considered to be the
most evolved species of nonhuman mammals, and also the most
human in terms of anatomy and aspects of be hav ior. Similarities to
humans include occasional bipedalism, manual dexterity of hands,
and va ri e ties of gestural and vocal communication. Prob ably for that
reason, there has been a tendency to assume that they are more “intelli-
gent” than other mammals, with richer cognitive systems and bigger
brains. So they are presented as a model of human ancestry.
However, studies of primate cognition and its origins also tend to have
been infused with anthropomorphism and the liberal use of meta phors:
in some cases drawn from the neoliberal economics of Western socie-
ties. In this section, however, we must fi rst ask: To what extent do primates
have bigger brains? And to what extent are primates more “intelligent”
than other mammals?
Answers to the brain- size question, as evidence of cognitive ability, are
not straightforward. Primates generally have relatively bigger brains than
other mammals because of their fi ner visual discrimination and digital
dexterity. Th ose that forage for fruit have bigger brains than those that
eat leaves, perhaps because they need more detailed cognitive maps
for more scattered locations. And those that eat insects have still bigger
brains, because they need even fi ner sensory discrimination and motor
skills.
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