A series of rapid environmental changes in East Africa roughly 2
million years ago may be responsible for driving human
evolution, according to researchers at Penn State and Rutgers
University. "The landscape early humans were inhabiting
transitioned rapidly back and forth between a closed woodland
and an open grassland about five to six times during a period of
200,000 years," said Clayton Magill, graduate student in
geosciences at Penn State. "These changes happened very
abruptly, with each transition occurring over hundreds to just a
few thousand years." According to Katherine Freeman, professor
of geosciences, Penn State, the current leading hypothesis
suggests that evolutionary changes among humans during the
period the team investigated were related to a long, steady
environmental change or even one big change in climate. "There
is a view this time in Africa was the 'Great Drying,' when the
environment slowly dried out over 3 million years," she said.
"But our data show that it was not a grand progressi