Dmanisi dig continues to challenge survival theories

Tuesday, April 12, 2005

DENTON (UNT), Texas -- A recent excavation of a Homo erectus skull dating from 1.7 million years ago could dispel the idea of survival of the fittest.

"The skull may challenge prevailing scientific theories of human evolution and human migration out of Africa," said University of North Texas geography and anthropology researcher Reid Ferring.

A member of an international scientific research team, Ferring and his colleagues have been unearthing fossils from an archaeological site in Eurasia since August 1993. The site is located below the medieval ruins of Dmanisi, a town in the southern Republic of Georgia.

Now, Ferring is featured in discussions about the importance of the new Dmanisi skull discovery in the April 2005 issue of National Geographic and the April 2005 issue of Nature.

"The skull was completely toothless and well over 40 -- old age at the time," Ferring said. "The fact that all tooth sockets in the skull were filled in by bone indicate this early human lived a couple of years after his teeth fell out. He could have eaten soft foods or been fed by his companions."

Ferring concludes the individual was either strong enough to hunt for soft food or others provided food for him.

"The skull suggests early humans could have survived, because of social cooperation and traits like compassion," he said. "Cooperating with people could have been more important to survival than having a big brain."

Ferring said that social cooperation such as caring for the elderly could counter previous notions about how humans migrated out of Africa.

If the case for compassion is true, this would open up a new area for scientific discussion that could dispel previous notions about human survival, exploration and evolution, he said.

Ferring said it's possible that human behavior doesn't evolve over a slow period of time. He said that it's possible that early humans not only exhibited traits such as compassion, but survived because of them.

Ferring said prevailing theories about how humans left Africa point to sophisticated tools, taller bodies and bigger brains than those of the Dmanisi fossils.

"Discoveries at Dminisi have proven those previous theories to be wrong," he said.

"Dmanisi fossils show evidence of primitive tools, short bodies and small-brain ancestors," he said. "If bodies, technology or brains weren't essential in getting out of Africa, then perhaps social behavior was the key."

Ferring said this kind of social organization would be used for procurement of food, defense of the group and protecting young.

Ferring points to layers of volcanic ash that entombed the skull and said the fossil record reveals the rise and fall of many species at Dmanisi.

The Dmanisi site dates to about 1.77 million years ago, when the Earth's magnetic polarity reversed.

Ferring said along with humans, animals of known antiquity were present at Dmanisi, including a rodent, which lived only between 1.6 and 2 million years ago.

The new Dmanisi skull is among the most primitive individuals so far attributed to Homo erectus or to any species that is indisputably human. Analyzing the soil strata, sediments, animal fossils and stone artifacts at the site, Ferring and others have determined the newly found skull -- like early human remains also discovered in the same stratified living surface in 2000, 1999 and 1991 -- dates back to the latest Pliocene or earliest Pleistocene Epoch, approximately 1.77 million years ago.

With this latest find of the toothless skull, the Dmanisi discoveries continue to contradict previous theories that either physical change in height and speed and/or advances in stone technology were necessary for humans to have left Africa for Eurasia. However, 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.

Ferring, a UNT professor of geology and archaeology, is working on research grants from the L.S.B. Leakey Foundation and the National Science Foundation. On account of his expertise in the emerging field of geoarchaeology, he was asked to establish a date for the entire archeological site at Dmanisi in order to clear up the hotly debated age of a mandible uncovered in 1991.

For interviews, contact Ferring at (940) 565-2993 or call Roddy Wolper (940) 565-2943 or Cathy Cashio (940) 565-4644 in the UNT News Service.

UNT News Service Phone Number: (940) 565-2108