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- The King
- Pridružio: 18 Dec 2003
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Homo habilis i homo erectus postojali u isto vreme!
Prema najnovijem otkricu, evolutivno stablo coveka vise je zbun, nego stablo, s obzirom da su homo erectus i njegov prethodnik homo habilis izgleda jedno vreme zajedno postojali u Keniji tokom pola miliona godina.
Fossils challenge old evolution theory
By SETH BORENSTEIN, AP Science Writer
Thu Aug 9, 10:33 AM ET
WASHINGTON - Surprising research based on two African fossils suggests our family tree is more like a wayward bush with stubby branches, challenging what had been common thinking on how early humans evolved.
The discovery by Meave Leakey, a member of a famous family of paleontologists, shows that two species of early human ancestors lived at the same time in Kenya. That pokes holes in the chief theory of man's early evolution — that one of those species evolved from the other.
And it further discredits that iconic illustration of human evolution that begins with a knuckle-dragging ape and ends with a briefcase-carrying man.
The old theory is that the first and oldest species in our family tree, Homo habilis, evolved into Homo erectus, which then became human, Homo sapiens. But Leakey's find suggests those two earlier species lived side-by-side about 1.5 million years ago in parts of Kenya for at least half a million years. She and her research colleagues report the discovery in a paper published in Thursday's journal Nature.
The paper is based on fossilized bones found in 2000. The complete skull of Homo erectus was found within walking distance of an upper jaw of Homo habilis, and both dated from the same general time period. That makes it unlikely that Homo erectus evolved from Homo habilis, researchers said.
It's the equivalent of finding that your grandmother and great-grandmother were sisters rather than mother-daughter, said study co-author Fred Spoor, a professor of evolutionary anatomy at the University College in London.
The two species lived near each other, but probably didn't interact, each having its own "ecological niche," Spoor said. Homo habilis was likely more vegetarian while Homo erectus ate some meat, he said. Like chimps and apes, "they'd just avoid each other, they don't feel comfortable in each other's company," he said.
There remains some still-undiscovered common ancestor that probably lived 2 million to 3 million years ago, a time that has not left much fossil record, Spoor said.
Overall what it paints for human evolution is a "chaotic kind of looking evolutionary tree rather than this heroic march that you see with the cartoons of an early ancestor evolving into some intermediate and eventually unto us," Spoor said in a phone interview from a field office of the Koobi Fora Research Project in northern Kenya.
That old evolutionary cartoon, while popular with the general public, is just too simple and keeps getting revised, said Bill Kimbel, who praised the latest findings. He is science director of the Institute of Human Origins at Arizona State University and wasn't part of the Leakey team.
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Homo erectus mnogo vise licio na covekolikog majmuna!
Ancient human fossils show women much smaller
By Tim Cocks
Thu Aug 9, 10:18 AM ET
NAIROBI (Reuters) - Homo erectus, long viewed as a crucial evolutionary link between modern humans and their tree-dwelling ancestors, may have been more ape-like than previously thought, scientists unveiling new-found fossils said on Thursday.
Revealing an ancient skull and a jawbone from two early branches of the human family tree -- Homo erectus and Homo habilis -- a team of Kenyan scientists said they were surprised to find that early female hominids were much smaller than males.
The skull was the first discovery of a female Homo erectus.
It suggests mankind's upright ancestors may have been physiologically closer to modern gorillas and chimpanzees, which also exhibit big differences in size between males and females, than had been supposed.
"Prior to the discovery of the new specimens, scientists did not know that Homo erectus males were far larger than the females," said Dr Emma Mbua, one of the team.
"This sexual dimorphism is considered a primitive character because it occurs in other apes," she said, standing in front of the bones at Kenya's National Museum.
She said this could also mean the sexual behavior of Homo erectus was more like that of apes, where individuals, especially males, mate with several partners, sometimes in a few hours, than that of its more monogamous human successors.
The fossils, discovered in east Africa's Rift Valley, regarded as the "cradle of humankind," challenge the idea that human prototypes evolved one after the other in a linear fashion from Homo habilis to Homo erectus, ending with modern humans.
Both fossils were found in 2000 east of Lake Turkana. But the Homo erectus skull, dating back 1.55 million years, was slightly older than the Homo habilis jawbone, which was found to be 1.44 million years old, the scientists said.
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