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Lucy's new kin take a powerful stand.

In the mid-1970s, excavations at Hadar in Ethiopia and Laetoli in Tanzania turned up the 3- to 3.6-million-year-old remains of Lucy and her kin, the earliest known hominids, or members of the human evolutionary family. The first major discovery since then of fossils belonging to Lucy's species, Australopithecus afarenis, fleshes out an intriguing picture of our acient ancestors: brawny creatures of both sexes who largely abandoned the trees in favor of efficient, two-legged walking and successful adaptation to diverse surroundings, from dry savannas to wooded lakeside locales.

"These early hominids attached themselves to a variety of ecologies," asserts Tim D. White, an anthropologist at the University of California, Berkeley "I suspect they lived all over the place in Africa."

White directed the fall 1990 excavations that uncovered the new A. afarensis specimens at an Ethipian site called Maka, about 30 miles sout of Hadar. He also took part in many of the earlier discoveries of Lucy's kin.

An analysis of the fossils unearthed in 1990, published in the Nov. 18 NATURE, supports the view that A. afarensis specimens compose one species--rather than two, as argued by some researchers--that retained the same basic skeletal anatomy for at least 500,000 years.

Maka hominid finds include a nearly complete jaw containing most of its teeth, much of an upper-arm bone, a partial lower-arm bone, two partial jaws, and several isolated teeth. Excavations also yielded more than 100 fassils of other animals, such as baboons, antelope, elephants, and crocodiles.

Contamination of volcanic ash at Maka prevents direct dating of the remains, White notes. But the chemical composition of hominid-bearing sand and gravel matches that of soil at a nearby archaeological site dated at 3.4 million years old, he says. Moreover, both sites contain the same types of nonhuman animals, the Berkeley anthropologist says.

A. afarensis individuals varied greatly in size, according to White. Hominid teeth found at Maka span the range of known sizes for A. afarensis. And while the lower-arm bone corresponds to Lucy's relatively small arm, the upper-arm fossil comes from a larger, male hominid, White contends. Computer simulations of A. afarensis bodies generated by C. Owen Lovejoy of Kent (Ohio) State University on the bias of fossil data from Maka and elsewhere also suggest that both male and female A. afarensis came in a variety of sizes.

The thickness of the upper-arm bone and its deep pits for muscle attachments denote a creature of great strength. However, the bone's short length contrasts with the long limbs of tree-dwelling apes such as orangutans, White holds.

"These were muscular, burly hominids, much stronger than modern humans," remarks Steve Ward, and anthropologist at Northeastern Ohio University College of Medicine in Rootstown, who has examined the Maka fossils. "They didn't spend more than a passing amount of time in the trees."

An upper-leg bone found at Maka about 10 years ago also shows a hip attachment specialized for walking, adds Lovejoy.

These observations clash with the view that at least some of Lucy's kin spent a lot of time in the trees (SN: 7/2/83,p.8).

The Maka jaw belonged to a young adult male and closely resembles a partial jaw perviously found at Laetoli, White asserts. Degeneration of the bone at the two points where it connected to the skull provides the earliest evidence of temporomandibular joint disease in hominids, he notes.
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Title Annotation:earliest known hominids
Author:Bower, Bruce
Publication:Science News
Date:Nov 20, 1993
Words:563
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