From: David N. Barnett 

Looks like Tim White and his Ardipithecus is starting to surface, finally.

http://story.news.yahoo.com/news?
tmpl=story&u=/nm/20040304/sc_nm/science_human_dc

Early Human Ancestor Had Small Teeth Thu Mar 4, 2:02 PM ET

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) - A 6 million-year-old creature that lacked sharp
canines for fighting may be the first pre-human to have branched off from
the ape line, researchers said on Thursday.

The short, small-brained creature may provide a good hint of what the
common ancestor of chimpanzees and humans looked like, the researchers
said.

Fossil remains of the early hominid were found in Ethiopia three years ago,
and it seemed to be a subspecies of a known pre-human, Ardipithecus
ramidus.

But the scientists have found more teeth from a group of the hominid,
re-classified it as a distinct species and named it Ardipithecus kadabba.

"Ardipithecus kadabba may also represent the first species on the
human branch of the family tree just after the evolutionary split between
lines leading to modern chimpanzees and humans," said Yohannes
Haile-Selassie, curator and head of physical anthropology at the Cleveland
Museum of Natural History in Ohio, who led the study.

His team's report, published in Friday's issue of the journal Science,
suggests that the last common ancestor of chimps and humans had long
canines used to fight -- something chimps have today, but not humans.

The researchers dug up fossils from at least five individuals who once
lived in a wooded environment, now a dry, rocky area in the Afar rift of
Ethiopia's Middle Awash region -- a rich source of pre-human remains.

They had enough to determine that it was an upright-standing hominid about
the size of a chimpanzee that lived between 5.2 and 5.8 million years ago.

Six new teeth were found at the site in 2002 and included an upper canine,
premolars from both jaws, and upper molars.

"We see a lot of primitiveness in the teeth," Haile-Selaisse said
in a telephone interview.

One key characteristic is a self-sharpening function.

"The canine tooth comes across the outside face of the lower premolar
and it sharpens that way," said Tim White of the University of
California Berkeley, who worked on the report.

"It is like honing a knife on a stone. Almost all of the monkeys and
all of the apes, they have all very long and projecting canines (with this
mechanism)."

In modern apes these sharp teeth are used by males for fighting, or to
frighten off an aggressor. The theory is that hominids evolved more
peaceable behavior, said White, with females choosing males who could stand
upright and help raise young over males who were busy fighting and showing
off.

Fossil remains of similar creatures found in Chad and Kenya are similar
enough to suggest they are closely related -- even in the same genus as
Ardipithecus, the researchers said.

"We now have an assemblage or set of early canines and none of them
are big and slashing," White said.

"What this indicates is that earliest hominids had these small canines
that were in the same animal as a small brain -- we know that from skull in
Chad -- and that head was attached to a bipedal body."

One of the most famous pre-humans, "Lucy" or Australopithecus
afarensis, dates back 3 million years. "This doubles the time period
all the way back to 6 million years that a small-brained, small-canine
bipedal early hominid existed," White said.

Genetics tells scientists that chimpanzees and hominids diverged from a
common ancestor around 7 million years ago. "But genetics can't tell
us what this animal was like," White said.

It is also becoming clear that looking at chimpanzees, who evolved as much
as humans did if not more over this period, do not provide a good model of
the ancestor, either.

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