Redefining Reality - The Intellectual Implications of Modern Science

But evolutionary psychologists Leda Cosmides and John
Tooby noted that when one small change is made to the test,
test has different results. About 65% to 80% of test subjects
can solve the problem. Supplying a context for the problem
seems to make all the difference.
The important point for evolutionary psychologists is that the
programs stored in the computers of our brains are not universal
particular tasks. We can detect what kinds of tasks they are by
seeing where they work well; then, we can start to think about
why we would have such programs embedded in our brains.
The third fact is that all humans come from a single, small group
of ancestors whose brains rapidly increased in size. We all get the
genetic basis for our neural development from the same source.
About 4 million years ago, , our
earliest ancestor to have split off from the evolutionary lines
of other great apes, appeared in Africa. They had brains about
the same size as the ancestors of chimps and gorillas. They are
Homo because they do not share the
standard traits we use to differentiate our later relatives.
Homo habilis; we see
some tool use and a somewhat larger brain—about half the size
of that in modern humans.
About 1.8 million years ago, appeared, with a
larger brain. spread out across Africa and Asia
but was eventually overrun by Homo sapiens, who evolved
out of a small group in east Africa about 250,000 years ago.
Indeed, the biochemist Allan Wilson was able to trace the roots
of humanity back to a single ancestor, Mitochondrial Eve.
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