Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, August 17, 1995 TAG: 9508170031
SECTION: NATIONAL/INTERNATIONAL PAGE: A9 EDITION: METRO
SOURCE: The Washington Post
DATELINE: LENGTH: Medium
Researchers in Northern Kenya have discovered fossil remains of a species of human ancestor who walked upright on two feet more than four million years ago, indicating that humanity's forbears developed this form of locomotion at least half a million years earlier than previous evidence indicated.
Although the hairy, 110-pound creature had the upright posture of a modern human, the fragments show that it still had the small brain and other primitive characteristics of an ape.
``This gets close to the hypothesized time of splitting of the ape and human lineages,'' said paleoanthropologist Alan Walker of Pennsylvania State University, a member of the research team. The newcomer may be the oldest known human ancestor, he said. But a rival for that title, reported last year from fossils found in Ethiopia, is still being evaluated.
The discovery, announced Wednesday and reported in the Aug. 17 issue of the science journal Nature, is the latest in a recent burst of evidence in the search for the so-called missing link between apes and humans. As a result, scientists said, the portrait of that transitional creature is rapidly growing richer and more complicated.
``We've got a `bushiness' to the family tree now that probably wasn't there before,'' Walker said, referring to evidence that there may have been more than one type of human ancestor evolving in the prehistoric forests at a given moment, and that they did not necessarily abandon their tree-swinging ways immediately after they took up bipedalism. ``There may be many ways of being bipedal.''
Paleontologist Peter Andrews of the Natural History Museum in London, discussing the new findings in a companion article in Nature, writes, ``The competition for the oldest [human ancestor] seems to be hotting up.''
The Kenyan bone fragments, scarred by the teeth of ancient carnivores, are between 4.1 and 3.9 million years old. They include complete upper and lower jaws, a complete set of lower teeth, a piece of skull including the ear region, isolated teeth from several individuals and a shin bone, according to Meave Leakey, leader of the research team from the National Museums of Kenya. In an article in the September issue of National Geographic, whose organization funded the project, she describes the painstaking, decades-long research.
The most complete specimens of the newly discovered species, named Australopithecus anamensis, were found at Kanapoi, southwest of the green inland sea known as Lake Turkana. Other specimens were found east of the lake, at Allia Bay. All came from sediments associated with the ancient precursor lake, known as Lonyumum.
The species appears to be ``directly ancestral to'' the short, apelike A. afarensis, of which the best-known example goes by the nickname ``Lucy,'' found in Hadar, Ethiopia, in 1974, Walker said. A. afarensis walked the earth as long as 3.6 million years ago and, for 20 years, was unchallenged as the earliest known human ancestor.
Then last year, a team led by Tim White of the University of California at Berkeley, announced the discovery in Ethiopia of fossil remains 4.4 million years old. That species, at the time called Australopithecus ramidus, was widely hailed as the closest so far to the missing link. Since then, however, White has changed the genus from Australopithecus to Ardipithecus, or ``ground ape,'' but has not yet published a paper explaining his reasons. He is continuing his research in Ethiopia and could not be reached for comment.
All members of the Australopithecus clan, including Lucy, are upright, bipedal creatures with ape-sized brains and large teeth with thick enamel, and the males weigh twice as much as the females.
by CNB