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article imageFossil Find Challenges Evolutionary Theory

By Chris Hogg     Aug 9, 2007 in Science
Two fossils found in Kenya are presenting a direct challenge on the theory of evolution. According to a new study, scientists say evolution might not have been a linear progression from apes to humans.
Digital Journal — Dr. Meave Leakey, a world-renowned palaeontologist, has a bone to pick with fossils. More specifically, her research is flipping conventional evolutionary theory on its cranium.
Everyone has seen the famous evolutionary image: an ape evolves to walk upright, eventually transforming into a homo sapien. In the field of science, it's been the widely accepted view of how humans evolved, but it might not be accurate.
After finding fossils in Turkana in northern Kenya in 2000, Leakey and her team spent years researching and looking at the fossils in the lab. The team studied an upper jaw bone of Homo habilis, finding it to be 1.44 million years old — much older than all previous discoveries of habilis bones. They also looked at a 1.55-million-year-old Homo erectus.
Rather than one species evolving into the other, as conventional science says, Leakey and her international research team say the two different species of early man lived side by side together for almost half a million years.
Scientists say habilis was likely to be vegetarian, while erectus ate meat.
The news is creating a fury of debate in the science world, after appearing today in the science journal Nature.
If research by Leakey and her team is correct, it would mean both habilis and erectus originated from a common ancestor. It puts evolutionary theory into a tornado of questions, as the fossils date two to three million years old, a period where scientists and fossil hunters had virtually no evidence.
A homo erectus skull. - Photo courtesy National Museums of Kenya
A homo erectus skull. - Photo courtesy National Museums of Kenya
Scientists say the findings don't change the relationship of erectus to Homo sapiens, as the former is still a direct ancestor of the latter. Instead, the surprisingly small erectus skull has scientists believing erectus was not as human-like as previously believed. The skull is very similar to modern gorillas, sending researchers on the hunt now for erectus's real ancestor.
ANU geologist Ian MacDougall, a member of the research team, told ABC News:It would suggest that the two species lived in the same area but must have different ecological niches, as it were. They weren't seriously competing, otherwise one would have expected the one species to completely dominate, and in fact wipe out a less adaptive species. It really does throw into doubt a whole series of assumptions that have previously been made on the basis of the fossils.MacDougall does caution, however, that scientists shouldn't be running out to rewrite history. In the same interview, he said:I don't think it throws into question the linear model from erectus to sapien. But who knows what will turn up tomorrow? It makes it just a little more complicated, and that's been the story of the discussions on prominent evolution and particularly these early fossils found in Africa. The evolutionary tree is much more bushy than was thought even 10 years ago.In a statement, Leakey said, "Their coexistence makes it unlikely that Homo erectus evolved from Homo habilis," Leakey said. "The fact that they stayed separate as individual species for a long time suggests they had their own individual niche, thus avoiding direct competition."
More about Fossils, Evolution, Ape, Human