Fossil Suggests Diverse Migration
Thu Jul 4, 2:00 PM ET
By PAUL RECER, AP Science Writer
WASHINGTON (AP) - It may have been a surprisingly diverse mixture of human-like creatures who first migrated from Africa and lived together in Eurasia 1.7 million years ago, according to scientists who have found a skull and other fossils in the Republic of Georgia.
A skull found in an excavation in southern Georgia is smaller and more primitive than two others found at the same site two years ago. Researchers said they also found a jawbone from what may be a third type of early human. The findings suggest that human-like species of various kinds may have traveled or lived together after leaving Africa as history's first migrants.
"We may have three distinct groups together at one site at the same time, 1.7 million years ago," said Reid Ferring, an archaeological geologist from the University of North Texas. "That is more variety at one site and time than anybody has ever dreamed possible."
Ferring is part of a team of researchers from the United States and the Georgian Academy of Sciences that is exploring layers of fossils uncovered beneath the ruins of a medieval town called Dmanisi. A report on their latest discovery appears Friday in the journal Science.
Two years ago, the same researchers stunned experts on primitive humans by announcing the discovery of two skulls at Dmanisi that were age dated at 1.7 million years old, making them the oldest human ancestral fossils ever found outside of Africa, which is thought to be where humans first evolved. Before that discovery it was thought that a more advanced human species first left Africa about 1 million years ago.
Those first two skulls were thought to be like the early Homo erectus or Homo ergaster found in Africa and dated at about 1.8 million years. The new skull also is thought to be early Homo erectus or ergaster, but its brain pan is about 25 percent smaller and appears to be more primitive, said Ferring. The jawbone may be from a third and even more ancient group, called Homo habilis, which has never before been found outside Africa.
"This was completely unexpected because until now, prevailing scientific views placed habilis, ergaster and erectus into an evolutionary sequence," said Ferring. Now, he said, there is a possibility that they were together at the same place and time, but that interpretation has yet to be confirmed by others.
Researchers have also found primitive stone tools at the site.
The small brain size of the new find and the crude stone tools runs counter to the belief of some experts that humans did not leave Africa until they developed brains larger than Homo erectus and had learned to make more sophisticated tools.
David Lordkipanidze of the Georgian Academy of Sciences said in a statement that the small brain size of the new discovery "suggests that enlargement of the brain was not the only reason to leave Africa."
"My feeling is there should be a combination of reasons, not just one reason, that forced people out of Africa," he said.
Milford Wolpoff of the University of Michigan was skeptical, saying in Science that there is "not a chance" that the fossils from Dmanisi represent more than one species. He suggests the small skull of the new find may be from a youngster that was still growing.
In another comment in Science, Daniel Lieberman of Harvard University said if the discoveries by Ferring, Lordkipanidze and their co-authors are confirmed, it will "throw a monkey wrench into many people's ideas about early Homo migration out of Africa."
Ferring said that the early migrating Africans may have felt right at home when they reached Georgia. He said the excavation also uncovered bones of many animals like those in Africa, including rhinos, elephants, giraffes and horses. There are also fossil remains of deer, pigs, bears and wolves, attesting to the hunting culture of the early humans.