Science marches on.
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Anthropologists find 4.5 million-year-old hominid fossils in Ethiopia
BLOOMINGTON, Ind. -- Scientists from Indiana University Bloomington and
seven other institutions have unearthed skeletal fossils of a human
ancestor believed to have lived about 4.5 million years ago. The
fossils, described in this week's Nature (Jan. 20), will help scientists
piece together the mysterious transformation of primitive chimp-like
hominids into more human forms.
The fossils were retrieved from the Gona Study Area in northern
Ethiopia, only one of two sites to yield fossil remains of Ardipithecus
ramidus.
"A few windows are now opening in Africa to glance into the fossil
evidence on the earliest hominids," said IUB paleoanthropologist Sileshi
Semaw, who led the research.
Semaw and colleagues also report new evidence that suggests the human
ancestors lived in close quarters with a menagerie of antelope, rhinos,
monkeys, giraffes and hippos in a northern Ethiopia that was far wetter
than it is today. The environmental reconstructions suggest a mosaic of
habitats, from woodlands to grasslands. Research is continuing at Gona
to determine which habitats A. ramidus preferred.
"We now have more than 30 fossils from at least nine individuals dated
between 4.3 and 4.5 million years old," said Semaw, Gona
Palaeoanthropological Research Project director and Stone Age Institute
research scientist. The Stone Age Institute, a new research center
dedicated to the study of early human evolution and culture, is
affiliated with Indiana University's CRAFT, the Center for Research into
the Anthropological Foundations of Technology.
In their letter to Nature, Semaw and his coauthors describe parts of one
upper and two lower jaw bones -- with teeth still intact -- several
loose teeth, part of a toe bone and intact finger bones. The scientists
believe the fossils belong to nine individuals of the species A.
ramidus. The scientists used argon isotope dating of volcanic materials
found in the vicinity of the fossils to estimate their age.
In the 11 years since the naming of A. ramidus by University of
California Berkeley anthropologist Tim White and colleagues, only a
handful of fossils from the species have been found, and only at two
sites -- the Middle Awash and Gona, both in Ethiopia. Other fossils of
slightly older age are known in Kenya and Chad. Anthropologists working
in Ethiopia believe Ardipithecus is the first hominid genus -- that is,
human ancestors who lived just after a split with the lineage that
produced modern chimpanzees.
Despite the millions of years that separate us, modern humans have a few
things in common with A. ramidus. Fossils from Gona and elsewhere
suggest that the ancient hominid walked on two feet and had
diamond-shaped upper canines, not the "v"-shaped ones chimps use to
chomp. Outwardly, however, A. ramidus would appear a lot more
chimpanzee-like than human.
Gona has turned out to be a productive dig site. In a Nature cover story
(Jan. 23, 1997), Semaw and colleagues reported the oldest known stone
tools used by ancestral humans. The Gona artifacts showed that as early
as 2.5 million years ago, hominids were remarkably skilled toolmakers.
Last month (December 2004), Semaw coauthored a paper in Geological
Society of America Bulletin summarizing Gona's geological properties and
the site's cornucopia of hominid fossils spanning several million years.
(Science magazine gave the article an "Editor's Choice" nod.)
Scott Simpson (Case Western Reserve University School of Medicine and
the Cleveland Museum of Natural History), Jay Quade (University of
Arizona), Naomi Levin (University of Utah), Robert Butler (University of
Portland), Paul Renne (Berkeley Geochronology Center and the University
of California, Berkeley), William McIntosh (New Mexico Bureau of Geology
and Mineral Resources and New Mexico Tech.), Manuel Dominguez-Rodrigo
(Universidad Complutense de Madrid) and Michael Rogers (Southern
Connecticut State University) also contributed to the report. It was
funded by grants from the Leakey Foundation, the National Science
Foundation, the National Geographic Society and the Stone Age Institute.
The authors thank Ethiopia's Authority for Research and Conservation of
Cultural Heritage, the National Museum of Ethiopia, and the Ethiopian
Ministry of Youth, Sports and Culture for providing permits for the
ongoing work at the Gona dig site, and the Afar people for making the
fieldwork a success.
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http://newsinfo.iu.edu/news/page/normal/1822.html
--
John Hachmann aa #1782
Intelligent Design has as much to do with science as reality
television has to do with reality. - Barry Lynn on CNN 12/25/04
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