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Chinese skulls face evolutionary mosaic.

Since the 1970s, farmers tilling the soil along a ridge overlooking China's Han River have occasionally turned up fossil bones of long-extinct animals. That sparked the interest of Chinese paleontologist Li Tianyuan of the Hubei Institute of Archaeology The Institute of Archaeology is an academic department of University College London (UCL), in the United Kingdom. The Institute is located in a separate building at the north end of Gordon Square, Bloomsbury.  in Wuhan, who led excavations at the site in 1989 and 1990 that yielded two nearly complete adult skulls of human ancestors dating to approximately 1 million years ago.

The specimens provide evidence that anatomically diverse populations of Homo erectus once lived throughout the Old World and independently gave rise to modern humans, assert Li and Dennis A. Etler of the University of California, Berkeley The University of California, Berkeley is a public research university located in Berkeley, California, United States. Commonly referred to as UC Berkeley, Berkeley and Cal , in the June 4 NATURE. Their conclusion contrasts with the theory, also based on fossil evidence, that modern Homo sapiens arose in Africa and eventually settled in Asia and other regions.

Although both Chinese skulls remain largely intact, they did suffer varying degrees of crushing and flattening; this has obscured some important measurements, such as the volume of the braincase brain·case
The part of the skull that encloses the brain; the cranium.

After viewing slides of the new fossils at the annual meeting of the American Association of Physical Anthropologists The American Association of Physical Anthropologists (AAPA) is an American-based international scientific society of physical anthropologists. It was formed in 1930. They have 1,700 members.  in April, G. Philip Rightmire of the State University of New York at Binghamton Binghamton University, State University of New York, or their officially adopted name, Binghamton University, is a coeducational public research university located in Vestal, New York.  questioned whether scientists could assign the misshapen mis·shape  
tr.v. mis·shaped, mis·shaped or mis·shap·en , mis·shap·ing, mis·shapes
To shape badly; deform.

 skulls to any species without a careful reconstruction of the crushed portions.

The limestone-encrusted specimens will be difficult to reconstruct, but they still preserve an "immense amount" of anatomy, Etler responds. "These are among the largest fossil crania cra·ni·a  
A plural of cranium.
 of human ancestors ever discovered," he says.

The skulls, dated on the basis of extinct animal bones found in the same layer of sediment, display facial features much like those of early modern humans, Li and Etler maintain. These include a flat face with a nonprotruding jaw and a distinctively oriented upper jaw. However, the fossils also preserve more primitive features typical of H. erectus, namely, a long, low, sharply angled braincase; thick bones around the ear holes; a long, narrow jaw joint; and signs of a relatively flat cranial base.

This mosaic of advanced facial features and a more primitive look elsewhere on the skull also turns up on other east Asian fossil hominids (members of the human evolutionary family) from the same time period, the researchers point out. Anthropologists usually classify all of these remains as H. erectus, a species thought to have lived from about 1.6 million to 400,000 years ago.

A different mosaic pattern characterizes European and African fossil hominids that date to the same period as the Chinese finds, Li and Etler contend. It consists of a more primitive, angled facial arrangement combined with advanced traits elsewhere, such as a higher, rounder braincase and a discernible curve in the base of the skull The base of the skull (lat. basis cranii) is the most inferior area of the skull.

Structures found at the base of the skull are for example:
  • Foramen magnum
  • Foramen ovale (skull)
  • Ethmoid bone
  • Sphenoid bone
. Some investigators consider the latter changes critical to human development and thus place the origin of our species in Africa.

Etler disagrees. "A different mosaic of features reflected the move toward modern human [anatomy] in different areas of the world," he argues. "No hominid hominid

Any member of the zoological family Hominidae (order Primates), which consists of the great apes (orangutans, gorillas, chimpanzees, and bonobos) as well as human beings.
 population at any one place, including Africa, was more intimately tied to human origins than any other population living around 1 million years ago."

The varying mosaic of human evolution in different areas makes it difficult to define fossil species on the basis of "primitive" and "advanced" anatomical traits, Etler adds. Investigators should look for evidence of population dispersals, climate shifts and other factors that may have kindled kin·dle 1  
v. kin·dled, kin·dling, kin·dles
a. To build or fuel (a fire).

b. To set fire to; ignite.

 regional changes in anatomy, he maintains.
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Author:Bower, Bruce
Publication:Science News
Date:Jun 6, 1992
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