Page 21 - Research 1.0

volume for both chimp and human babies increase at three times
the rate of infant macaques, however, during early childhood,
human brain expansion was twice that of chimpanzees due to
rapid growth of connections between brain cells. In the human

infant, fully 60% of caloric intake go into neuronal
development. For most other species, the necessity for such
a long childhood would place them at a survival disadvantage.

Two human characteristics, a large brain and a long childhood

are interrelated and both had their beginnings in our primate
ancestors. Unlike many other mammals whose survival was
dependant on large litters of young and the odds that at least
some of them would survive, Primates already had a larger
brain than most other mammals and parlayed that benefit into
having fewer offspring (only two 'feeding stations') and
investing time and effort in teaching survival tactics to
those offspring.

Evolution occurs by incremental modification of existing
structures. We see increases in brain size from Prosimians
(Strepsirrhini) to Simians (Haplorhini) with additional
increase from New World Monkeys (Platyrhini) to Old World

Monkeys and still further expansion in apes, particularly in
the Great Apes (Hominids). In general, that expansion of the
brain follows primate evolution.

That trend toward an ever larger cranial capcity is also seen
in the evolution of the human species. A brain, being soft
tissue, has not been found in fossils, but brain size can be
inferred from cranial capacity.

We are just now beginning to understand the environmental
pressures that lead to a larger brain; increasingly complex