Mon, Aug 13, 2012 - Page 9 News List

Fossils hint that our ancestors had distant relatives

Judging by new finds, ‘Homo erectus’ had company on the East African plains

By Seth Borenstein  /  AP, WASHINGTON

Illustration: Yusha

Our family tree may have sprouted some long-lost branches going back nearly 2 million years. A famous paleontology family has found fossils that they think confirm their theory that there are two additional pre-human species besides the one that eventually led to modern humans.

A team led by Meave Leakey, daughter-in-law of famed scientist Louis Leakey, found facial bones from one creature and jawbones from two others in Kenya. That led the researchers to conclude that man’s early ancestor had plenty of human-like company from other species.

These would not be Homo erectus, believed to be our direct ancestor. They would be more like very distant cousins, who when you go back even longer in time, shared an ancient common ancestor, one scientist said.

However, other experts in human evolution are not convinced by what they say is a leap to large conclusions based on limited evidence. It is the continuation of a long-running squabble in anthropology about the earliest members of our own genus, or class, called Homo — an increasingly messy family history. And much of it stems from a controversial discovery that the Leakeys made 40 years ago.

In their new findings, the Leakey team says that none of their newest fossil discoveries match erectus, so they had to be from another flat-faced relatively large species with big teeth.

The new specimens have “a really distinct profile” and thus they are “something very different,” said Meave Leakey, describing the study published online on Wednesday last week in Nature.

What these new bones did match was a fossil that Meave and her husband, Richard, helped find in 1972 that was baffling. That skull, called 1470, just did not fit with Homo erectus, the Leakeys contended. They said it was too flat-faced with a non-jutting jaw. They initially said it was well more than 2.5 million years old in a dating mistake that was later seized upon by creationists as evidence against evolution, because it indicated how scientists can make dating mistakes. It turned out to be 2 million years old.

For the past 40 years, the scientific question has been whether 1470 was a freak mutation of erectus or something new. For many years, the Leakeys have maintained that the male skull known as 1470 showed that there were more than one species of ancient hominids, but other scientists said it was not enough proof.

The Leakeys’ new discoveries are more evidence that this earlier “enigmatic face” was a separate species, said study co-author Fred Spoor of the Max Planck Institute in Germany. The new bones were found between 2007 and 2009, about 10km away from the old site near the fossil-rich Lake Turkana region, Leakey said.

So that would make two species — erectus and the one represented by 1470.

However, it is not that simple. The Leakey scientific team contends that other fossils of old hominids — not those cited in their new study — do not seem to match either erectus or 1470. They argue that the other fossils seem to have smaller heads and not just because they are female. For that reason, the Leakeys believe there were three living Homo species between 1.8 million and 2 million years ago. They would be Homo erectus, the 1470 species and a third branch.

“Anyway you cut it, there are three species,” said study co-author Susan Anton, an anthropologist at New York University. “One of them is named erectus and that ultimately, in our opinion, is going to lead to us.”

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