http://www.cnn.com/video/api/embed.html#/video/bestoftv/2013/10/18/ctw-skull-found-fred-spoor.cnn
By Elizabeth Landau, October 19, 2013
(CNN) — Fragments of humans’ ancient relatives are scattered across the globe. Sometimes a tooth or a few bones are all we have to tell us about an entire species closely related to humans that lived thousands or millions of years ago.
So when anyone finds a complete skull of a possible human ancestor, paleoanthropologists rejoice. But with new knowledge comes new controversy over a fossil’s place in our species’ very fuzzy family tree.
In the eastern European nation of Georgia, a group of researchers has excavated a 1.8 million-year-old skull of an ancient human relative, whose only name right now is Skull 5. They report their findings in the journal Science, and say it belongs to our genus, called Homo.
“This is most complete early Homo skull ever found in the world,” said lead study author David Lordkipanidze, researcher at the Georgian National Museum in Tbilisi.
Skull 5 is the fifth example of a hominid — a bipedal primate mammal that walked upright — from this time period found at the site in Dmanisi, Georgia. Stone tools and animal bones have also been recovered from the area.
The variation in physical features among the Dmanisi hominid specimens is comparable to the degree of diversity found in humans today, suggesting that they all belong to one species, Lordkipanidze said.
But “if you will put separately all these five skulls and five jaws in different places, maybe people will call it as a different species,” he said.
Now it gets more controversial: Lordkipanidze and colleagues also propose that these individuals are members of a single evolving Homo erectus species, examples of which have been found in Africa and Asia. The similarities between the new skull from Georgia and Homo erectus remains from Java, Indonesia, for example, may mean there was genetic “continuity across large geographic distances,” the study said.
What’s more, the researchers suggest that the fossil record of what have been considered different Homo species from this time period — such as Homo ergaster, Homo rudolfensis and Homo habilis — could actually be variations on a single species, Homo erectus. That defies the current understanding of how early human relatives should be classified.
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