Lecturer to Present Evidence on Climate’s Impact on Evolution

Lecturer to Present Evidence on Climate’s Impact on Evolution

RICE NEWS STAFF
Nov. 5, 1998

Peter deMenocal of the Lamont-Doherty Earth Observatory, Columbia University,
has found the first evidence that climate changes in Africa contributed to the
evolution of humans.

On Nov. 10, deMenocal, a paleoclimatologist, will discuss "Pliocene-Pleistocene
African Climate Change and Early Hominid Evolution" in a lecture at 4 p.m.
in the Biology Auditorium, Room 131, of the Biology Laboratory Building.

The lecture is sponsored by the Department of Geology and Geophysics and the
Department of Anthropology.

Analyzing ocean sediments near Africa’s eastern and western coasts, deMenocal
discovered the first detailed evidence that profound climate shifts on earth
may have changed the course of human evolution.

Soil particles and tiny remnants of grasses, blown out to sea by winds, revealed
that the continent suffered cycles of colder, drier climate about 2.8 million,
1.7 million and 1 million years ago. The three periods coincide with major steps
in human evolution as documented by the fossil record. The evidence strongly
suggests that shifting environmental conditions contributed to the extinction
of some human ancestors while other, more adaptable species survived.

The paleoclimatologist’s research for the first time links these African climate
shifts with the growth of ice sheets in North America and Europe. Using computer
models, he showed that expanding North American ice sheets would have chilled
the Atlantic Ocean, sending cold, dry air blowing across Africa. As the ice
sheets grew, cold and dry periods in Africa intensified.