Prehistoric man; A story written in footprints
Those three, striding upright across a vast East African plain in the shadow of an active volcano some 3.6 million years ago, could they have been a male and a female leading a little one by the hand -- an early precursor to the human family?Skip to next paragraph
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"It's purely hypothetical, but that's a possible interpretation," says Mary D. Leakey, world renowned paleoanthropologists, whose team found the trio's footprints at Laetoli in northern Tanzania last summer. "I think that may well be the true explanation. . . .
"All we can say is that we have three bipedal creatures who were walking along together, not hurrying, but walking quite calmly, not rushing away from some catastrophic event, but just walking due north across the duty, ashy plain."
What their incredible 73-foot-long trail of sharply-etched prehistoric footprints, identical to those of modern man, says to Mrs. Leakey is that these creatures were definitely hominids -- and therefore ancestors of hmankind -- walking with the same upright, free-swinging gait modern man does.
"On any grounds there is no real Rubicon you can cross over and say that on one side is man and on the other is not man. The whole evolutionary process is so gradual. But I myself believe that the Laetoli hominids were in the direct line of human evolution. . . . They were probably at a stage of evolution where you can't call them man. They were probably before man became man. But they are hominids."
These footprints and the numerous jawbones and teeth found at Laetoli rank as the oldest known human-like remains. Only the jaw bones and teeth known as Ramapithecusm found in Pakistan and India are older, dated at somewhere between 7 and 9 million years old.
The Laetoli discovery is especially exciting because it provides evidence that ancient man was bipedal far earlier than anthropoligists had speculated.
Mrs. Leakey's son, Richard E. Leakey, also an anthropologists, has been fossil hunting and finding for more than a decade at Lake Turkana in Kenya. He has also made spectacular discoveries.
"Material found by Richard," Mrs. Leakey says, "is about 2.6 million years old. Limb bones there show that the stance was upright and they were bipedal. And material found at Hadar in the Afar region of Ethiopia by Dr. Johanson certainly shows an upright stance and bipedalism at about 3 million years." Dr. Ronald C. Johanson is the curator of physical anthropology and the director of scientific research at the Cleveland Museum of Natural History.
Another extraordinary thing about finding the Laetoli prints is that they reveal not just the bone structure of early mortal man but the exact outline of the flesh -- the bare foot.
When they were first uncovered, Mrs. Leakey says her initial reaction was "a certain degree of disbelief. We all felt slightly incredulous about it because they were so entirely human in appearance. None of us had really expected footprints of that age to be so similar to our own."
For this discovery and many other startling finds unearthed during 37 years of dedicated work with her celebrated husband, the late Louis S. B. Leakey, Mrs. Leakey recently came to Boston to receive the 1980 Bradford WAshburn Award, given annually by the Boston Museum of Science to honor outstanding contributions to public understanding of natural science.
The exacting excavation and recording methods she pioneered are now in general use.
The Leakeys received the National Geographic Society's Hubbard Medal in 1962 for "revolutionizing knowledge of prehistory by unearthing fossils of earliest man and giant animals in East Africa."
The British couple began their work in 1935 at Olduvai Gorge, a deep gash across the Serengeti Plain about 30 miles north of Laetoli, which exposes layer upon layer of habitation ranging from 400,000 years ago at the top down to about 2 million years ago at its lowest level which the Leakey's have designated "Bed 1."
Year after patient year they clambered up and down this 30-mile long gorge under the full force of the equatorial sun during Tanzania's dry season -- July, August, and September. With dental picks, paint brushes and calipers they painstakingly ferreted out, identified, and measured thousands of fossils. They uncovered a circile of stones which Mrs. Leakey calls "the very earliest human structure any where in the world."