- Associated Press - Wednesday, August 8, 2012

Humanity’s 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, claims in new research made public Wednesday that they have 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 wouldn’t 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.

But other experts in human evolution aren’t convinced by what they say is a leap to large conclusions based on limited evidence. It’s 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 Maeve Leakey, describing the study published online Wednesday in Nature.

What these new bones did match was an old fossil that Mrs. Leakey and her husband Richard helped find in 1972 that was baffling. That skull just didn’t fit with Homo erectus, the Leakeys contended. They said it was too flat-faced with a non-jutting jaw. For the past 40 years, the scientific question has been whether the outlier skull was a freak mutation of erectus or something new. For many years, the Leakeys have maintained that the male skull showed that there were more than one species of ancient hominids, but other scientists said it wasn’t 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 six miles away from the old site near the fossil-rich Lake Turkana region.

So that would make two species - erectus and the one represented by the unusual skull, known to researchers as “1470.”

But it’s not that simple. The Leakey scientific team contends that other fossils of old hominids — not those cited in their new study — don’t 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,” 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.”

Both of the species that Maeve Leakey said existed back then went extinct more than a million years ago in evolutionary dead ends.

“Human evolution is clearly not the straight line that it once was,” Mr. Spoor said.

But Tim White, a prominent evolutionary biologist at the University of California Berkeley, isn’t buying this new species idea, nor is Milford Wolpoff, a longtime professor of anthropology at the University of Michigan. They said the Leakeys are making too big a jump from too little evidence.

Mr. White said it’s similar to someone looking at the jaw of a female gymnast in the Olympics, the jaw of a male shot-putter, ignoring the faces in the crowd and deciding the shot-putter and gymnast have to be a different species.