New Area Of Evolutionary Clues

Press, Volume CIX, Issue 32313, 3 June 1970, Page 14

New Area Of Evolutionary Clues

(By

MICHEL H. MATHIS

in the

“Christian Science Monitor")

Palaeontologist? are probing a vast new fos-sil-rich area that may fill many pages of a newly opened chapter in the history of human evolution; the record from 24 million years ago.

The new area lies in remote desert adjoining the eastern shore of Lake Rudolf in north-western Kenya. Before last year, exploration in that vicinity had produced tantalising bits and pieces of fossil evidence hinting that prehistoric hominids (manlike creatures) might have thrived there.

Now the experts are sure of It. Last summer they made three spectacular new finds of specimens preserved in the sediments and volcanic debris that blanket the site:

First they found a collection of primitive stone tools embedded in volcanic ash. British experts carefully analysed and dated the ash at almost 2.6 million years of age, proving the tools were 850,000 years older than any other tools yet found and dated. And the existence of tools suggested the presence of man’s early ancestors—creatures in the direct line of human evolution.

Then, in mid-summer, they found a nearly complete hominid skull. Its location suggested it was at least as old as the tools and -thus at least 850,000 years older than any other clearly dated hominid skull yet found. And it matched almost prefectly the fossil skulls of a strange “near-man” already known to anthropologists. Static Role Scientists dispute the technical name for this creature. Some call him Australopithecus boisei. Others call him Paranthropus or Zinjanthropus. With their latest find, the experts now know he thrived in southern and eastern Africa for more than 2 million years. But for all that time he scarcely changed or evolved. So, as evolution transformed his habitat, he became extinct.

Anthropologists do not think A. boisei could have been the toolmaker. And he definitely was not a direct ancestor of man. So, they ask, who was the toolmaker? The Lake Rudolf site’s third disclosure may provide the answer.

Late in the summer, experts there found the pieces of a partial fossil skull—missing its face, teeth, and jaws. The location of this new find suggests that it, too, is at least 2.6 million years old. The brain seems to have been larger than A. boiseis. And its shape appears to some experts to be unique. In their view the new skull does not seem to resemble any of the oldest hominid skull specimens previously known to anthropologists. But no one’s sure enough to give it a name.

Record Pushed Back

These new discoveries, and other recent finds near Lake Rudolf and in neighbouring Ethiopia, are the first to push the scientific record of human evolution back Into the time period between 2 and 4 million years ago. The new Lake Rudolf finds, confirming the spectacular potential of the area, have just been announced by Richard "E. Leakey, the 25-year-old son of famous Kenvan anthropologists Louis and Mary Leakey, j n .. the . cur £®" t issue of “National Geographic” magazine. “We have traced the outlines of what may be the richest and most extensive Pliocene-Pleistocene (2-4-mii-lion-year-old) fossil region known in all Africa, he writes. "Here lie more than a thousand square miles of sediments . . . bearing countless bones of extinct amnials —and, we now know, creatures akin to man.” In recent years scientists have been working with a log of human ancestry rich with trails of evidence of Modern man and his cultural ancestor, Cro-Magnon man, leading back more than 50,000 years. Then a somewhat broken record of several extinct races of Homo sapiens extends past the 100,000-year signpost and trails off into obscurity.

Evidence Stops A few hundred thousand years further back, another human species begins to show up: Homo erectus, known by various names such as Peking man, Java man, and Heidelberg man. Anthropologists have a variety of evidence that Homo erectus roamed a large part of the world even earlier than 500,000 years ago. But there the evidence stops. That’s the earliest scientists have confidently traced man’s direct ancestry, known by the

genus name Homo. And for the older, more controversial “hominid” remains, scientists almost necessarily turn to Africa.

There, particularly in the arid lands of Egypt, Ethiopia, Kenya,. Tanzania, and South Africa, determined experts like the .Leakey family are painstakingly gathering small pieces of a human evolutionary puzzle that may cover more than 30 million years. Probably the most famous and productive site there is Tanzania’s Olduvai Gorge, long the workshop of Richard Leakey’s parents. The eroded walls at Olduvai expose a magnificant fossil record that includes specimens of Homo sapiens in “recent” sediments near the top of the gorge, half-million-year-old specimens of Homo erectus further down, striking evidence of early manlike creatures near the bottom, and finally ends with 2-million-year-old volcanic lava.

Amazing Implication

Among the first of the ancient African finds were remnants of creatures closely related to Australopithecus boisei. Initial finds showed thgt this vegetarian near-man may have roamed the forest fringes of Africa as recently as his distant relative, the agile and meat-eating Homo erectus.

In 1959, Louis and Mary Leakey shook the scientific world by digging a nearly complete hominid skull from Olduvai that proved to be 1.75 million years old. 'lt was their choice of Australopithecus boisei as the name for this new find that first introduced it into scientific terminology. A few years later, experts at another Tanzanian site uncovered a similar skull that proved to be only half a million years old. That left anthropologists with the amazing implication that an early hominid species lived essentially unchanged for more than a million years. And now Richard Leakey has found another A. boisei skull that nearly matches his parents’ Olduvai specimen and yet seems to be nearly a million years older. It confirms that A. boisei’s successful but static role in African evolution lasted even more than 2 million years. Rapid Evolution This role provides a fascinating contrast with a series of discoveries that may prove even more important to the direct line of human evolution. For years scientists have been gathering bits and pieces of evidence pointing to a separate hominid species—a hunter and meat-eater—-coexisting with A. boisei, but evolving rapidly. The evidence first appeared in southern Africa in 1924 when Dr Raymond Dart discovered a prehistoric child’s skull which he named Australopithecus africanus. Since then anthropologists have been gathering a variety of associated fossils which now are believed to be well over 1 million and, perhaps, even more than 2 million years old. But none of these early finds include stone tools. Physical anthropologists currently think that toolmaking, erect walking, and increasing brain size are three key clues to and, perhaps, causes of man’s rapid evolution. Ancient tool finds tantalise these experts, but often leave them frustrated, as they are rarely able to find fossils of the creatures that made them. Vegetarian Offshoot That’s what happened to Dr Louis Leakey in Olduvai. Over a period of many years he gathered a collection of the oldest and most primitive stone tools then known. But he found no hominid fossils. Then, in 1959, he found his A. boisei skull. But that wasn’t adequate. That vegetarian offshoot from the main line of human evolution didn’t seem to be a likely toolmaker. Finally, in 1964, Dr Leakey announced that several newly found 1.75-million-year-old bone specimens suggested the existence. of yet another species: Homo habilis, the toolmaker and a direct ancestor, he maintains, to man.

Many scientists dispute the significance of this find. They say Homo habilis is just another variety of A. africanus. But Dr Leakey says he has new evidence, as yet unpublished, that supports his claim.

Meanwhile, though, his son has virtually duplicated his performance. The first discovery made by Richard Leakey’s expedition to Lake Rudolf last year was a tool find. “If further study verifies that these, indeed, are tools,” he writes, “we will have pushed back the horizon

of the earliest toolmaker some 850,000 years.” Then, near the end of the summer expedition, one of Mr Leakey's African associates found the mystery skull that may belong to one of the Lake Rudolf toolmakers, and could prove to be still another newly found species. Tantalising Questions

Mr Leakey’s skulls are the oldest yet found of man’s early relatives. Anthropologists presently have a few sets of jaws and teeth belonging to a 14-million-year-old man-like creature known as

Ramapithecus. But they still can’t tell whether he is likely to be in man’s direct ancestry. These new finds, of course, leave anthropologists with tantalising new questions:

Will the next finds link Australopithecus boisei and the mystery skull with each other and/or with Ramapithecus? Or is their real ancestor as yet undiscovered? And who is the direct ancestor to Homo erectus and Modern man? Is it Louis Leakey’s Homo habilis? Australopithecus africanus perhaps? And where does the new mystery man fit in? Perhaps new evidence will

link all these toolmaking hunters into the same tap root of Modem man’s genealogical tree—a root plunging millions of years into prehistory.

Found.rs’ Society.—Officer, elected at the recent annual meeting of the Canterbury branch of the New Zealand Founders’ Society were:—President, Mr N. Pearce; vicepresidents, Messrs F. R. Cullen and A. H. Struthers: secretarytreasurer, Miss M. E. Hulston; committee. Misses Slater, Herridge, Mateer and Haylock, Mesdames Perkin, Moorhead, Jones, Struthers, and Chapman. Messrs L. B. Prenderville and W. F. M. Bennetto.