Science: The Oldest Man

When Anthropologists Louis Leakey and his wife Mary began their search for man's origins in the 1930s, they paused briefly in a dry, remote region of Tanzania called Laetolil (after the Masai name for a hardy regional flower). The area's volcanic ash yielded fossils of many extinct creatures, but none that were even vaguely human. So the Leakeys continued their work at a more promising site, some 25 miles to the north in neighboring Kenya, called Olduvai Gorge. There they found the remains of hominid creatures that pushed man's lineage back to some 2 million years ago—at least a million years farther into the dark shadows of prehistory than had previously been suspected.

Last week Mary Leakey announced fresh findings that set man's genesis even deeper in the distant past. The evidence comes not from Olduvai but from Laetolil. Returning there after her husband's death in 1972, on a hunch "we didn't look hard enough," she began uncovering jawbones and teeth that seemed clearly human; that is, they belonged to the genus Homo (or true man), rather than to man-apes (like Australopithecus, who once was thought to be the forerunner of man but is now regarded as a possible evolutionary dead end). One clue was the teeth, which showed that the creatures were meat eaters. By the time she finished her collecting last summer, she had discovered bones from no fewer than eight adults and three children. "But we did not appreciate their significance until just last month," Leakey told a press conference in Washington last week. That was when University of California scientists at Berkeley finished radioactive dating of the volcanic ash in which the fossils were found. It revealed that they were from 3.35 million to 3.75 million years old.

Close Kin. If the bones do indeed belong to a true Homo, they provide one more link in a growing chain of evidence that indicates man's direct ancestors were stalking Africa's savannas—walking upright, perhaps hunting and using tools—as long as 4 million years ago. In 1972, following in his parents' footsteps, Richard Leakey discovered a nearly complete manlike skull at nearby Lake Rudolf in Kenya that is at least 2.6 million years old. More recently, Carl Johanson of Cleveland's Case Western Reserve University, digging in Ethiopia's bleak Awash Valley, discovered a manlike jawbone that seems to be well over 3 million years old (TIME, Dec. 2, 1974). If all these creatures are in fact close kin, they would, in Mary Leakey's words, be people "not unlike ourselves," though not much more than 5 ft. tall and with much shorter life spans and somewhat smaller brains.