UNT scientist says 1.75 million-year-old human fossils question theories of evolutionary sequence

UNT scientist Reid Ferring, chair of the Department of Geography, says ongoing studies of human fossil discoveries at Dmanisi in the Republic of Georgia may eventually pose challenges to prevailing scientific theories of human evolution and human migration out of Africa.

Ferring is a member of a Georgia-led international scientific research team that last August unearthed an early human skull from the same strata where the team previously discovered other significant human fossil remains at the unique archaeological site below the ruins of the medieval town of Dmanisi in southern Georgia.

Now, Ferring is one of the major authors of an article discussing the importance of the new find in the July 5 issue of Science.

Ferring emphasizes it is too early for the scientific team at Dmanisi to reach firm conclusions about what the site is telling them about the processes of human evolution, early human migration and development of stone tool technology. However, in comparing information about the 2001 specimens with the previous Dmanisi human fossils, Ferring is intrigued by the possibility that the early human community at the site was far more diverse than anyone could have predicted.

Ferring and his colleagues report that the characteristics of the newly discovered Dmanisi skull place it among the most primitive individuals so far assigned to Homo erectus or to any species that is indisputably human.

He says the new skull and other bones that appear to have come from the same individual are closely related to Homo habilis (an earlier, more primitive, smaller-brained human species), previously found only in Olduvai Gorge and Koobi Fora in Africa. No other specimen even generally resembling Homo habilis has ever been found outside of Africa.

Among the 1.75 million-year-old human fossils previously unearthed, the scientific team has identified skulls that resemble Homo ergaster and a mandible, or jaw bone, that falls well within the range of Homo erectus. Homo ergaster is a species more advanced than habilis, but more primitive than erectus.

"One of the puzzles yet to be solved at Dmanisi," Ferring says, "is that individuals showing traits of all three early human species appear to have been living there at the same time. This was completely unexpected, because until now, prevailing scientific views placed habilis, ergaster and erectus into an evolutionary sequence."

Homo erectus emerged as the only remaining early human species approximately 1.5 million years ago.

Since 1993, Ferring has worked summers at Dmanisi with other scientists from the Republic of Georgia, France, Germany, Italy, Spain, Switzerland and the United States. The group also involves student workers from around the world.

Analyzing the soil strata, sediments, animal fossils and stone artifacts at the site, Ferring and others have determined that the newly found skull – like early human remains discovered in the same stratified living surface in 2000, 1999 and 1991 – dates back to the latest Pliocene or earliest Pleistocene Epoch, approximately 1.75 million years ago.

The Dmanisi discoveries have contradicted previous theories that physical changes in height and speed and/or advances in stone technology were necessary for humans to have left Africa for Eurasia. Ferring says the fossils and tools from Dmanisi show clearly that other factors were involved. New kinds of social organization or possibly greater reliance on meat as a staple in colder environments may explain how these early humans succeeded in the exploration of Eurasia.

"A lot of hard work," Ferring explains, "separates us from answers to the many new questions Dmanisi has provided."

The environmental issues surrounding these earliest migrations are very significant. The thousands of animal fossils from Dmanisi reveal a much more African-like setting than exists in Georgia today. Bones of rhinoceroses, giraffes, saber-toothed cats, elephants and horses show that these people may have found quite familiar landscapes in Georgia. At the same time, fossil remains of deer, pigs, bears and wolves reflect the nearby forests of Georgia’s mountainous regions.

Ferring’s research is funded by grants from the L.S.B. Leakey Foundation and the National Science Foundation. Because of his expertise in the emerging field of geoarchaeology, he was originally asked to establish the date of the entire archaeological site at Dmanisi in order to clear up the hotly debated age of a mandible uncovered there in 1991.

BY RODDY WOLPER rwolper@unt.edu

Other featured articles in this issue

• Regents name Dallas County Judge Lee Jackson as UNT System chancellor finalist
• New video created to boost UNT spirit and pride
• New director of women's studies selected
• Postal rates up as of June 30
• UNT departments move to new locations
• Staff Council changes bylaws to include UNT System staff
• Pohl recognized as outstanding administrator
• UNT parking permits for 2002-03 now for sale through intercampus mail
• Faculty Senate meets for the last time during 2001-02 year
• First aid kit supplies for sale

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