Anthropologist Richard E. Leakey stressed that much remains to be discovered about man's evolution at a conference on the origins of man last weekend.

Delivered before a crowd of over 500 people at John Hancock Hall in Boston Friday night, Leakey's speech kicked off a two-day lecture series sponsored by Harvard's Peabody Museum and Museum of Comparative Zoology, the Boston Museum of Science and the Foundation for Research into the Origins of Man (FROM).

"Never before have we been able to discover so much about the origin of man." Leakey said. "One can only speak of what one knows and expose the great extent of what one doesn't know."

Leakey, the chairman of FROM, discussed several areas for investigation, including the point at which man and ape diverged in the evolutionary sequence, the causes of the brain enlargement of man and his most recent ancestors, and the origins of primitive art. He also argued that it was the move to a bipedal stance--not the development of tool-making or the enlargement of the brain--that spurred man's evolution.

The conference moved to the Science Center Saturday for a full day of lectures, attended by more than 400 people, on the environment and human evolution.

David R. Pilbeam, professor of Anthropology and one of the event's organizers, spoke on man's most primitive ancestors, who lived from 2.5 to 10 million years ago. The two principal elements in man's divergence from the apes were the development of bipedalism and the decrease in size of the canine teeth; brain and tool-making skills did not develop until later, he said.

William W. Howells, professor of Anthopology emeritus, said in a later speech that racial differences can be traced to differences in geographical conditions 40,000 years ago, citing as proof the structures of skulls of that period from different parts of the world.