Human evolution
Human beings evolved from ape-like ancestors. The
chimpanzee has almost identical genetic make up as humans. However,
there is disagreement about the details of the progressive changes
and the dynamic causes underlying evolution.
The human family first appeared in Africa about
5-6 million years ago. A second event, the migration out of Africa,
occurred close to 2 million years ago. Until 30,000 years ago the
fossil skulls found in Africa, Asia and Europe show a lot of
anatomical differences. This is taken as evidence of several human
species coexisting as a result of adaptive radiation of the primary
human African stock. This is the 'out of Africa' hypothesis that
says that modern humans evolved in an isolated population about
150,000 years ago with its descendants subsequently moving into the
rest of the world. Almost certainly, everyone in the world today is
a descendant of just one of these several populations, who in their
inexorable spread across the world caused the extinction of species
of humans who were like us but were not us. Some 40,000-50,000
years ago, a group of Middle Eastern people developed a type of
tool that seems to have precipitated a radical expansion of the
human mind and a new way of thinking about the environment,
particularly the use of tools for survival. These pre-agricultural
people developed the Aurignacian episode of cultural ecology.
They lived perhaps 2,500 generations ago. The principal
technologies were the use of fire and a relatively simple kit of
stone flake tools. This tool kit was the product of nearly 2.5
million years of development.
Fewer than 500 generations later Homo
sapiens had become something more than merely a large, common
primate. It took only an eyeblink of evolutionary time. We, the
generations who share the planet today, are facing a challenge to
innovate on a level that may be as profound as the achievement of
our distant ancestors. But we do not have 500 generations' worth of
time to accomplish the task. It has been said that, depending on
the degree of misery and biological impoverishment that we are
prepared to accept, we have only one or perhaps two generations in
which to reinvent a survival kit to sustain a new post-industrial
cultural ecology.