Step Closer to First Humans

[Tracey]

 Ape Remains Take Science Step Closer to First Humans
By Mark Henderson, Science Correspondent
 
 
THE remains of at least nine ape-like creatures of a
species that was one of humanity’s oldest known
ancestors have been discovered in Ethiopia, shedding
important light on the first chapters of human
evolution.

The new fossils belong to a hominid species known as
Ardipithecus ramidus that lived 4.5 million years ago,
of which only a handful of examples have been
identified previously.

The find, by a team led by Sileshi Semaw, of Indiana
University in the United States, promises to transform
scientists’ understanding of the evolution of
primitive, chimp-like early hominids into more
recognisably human creatures.

Ardipithecus ramidus, which was first identified in
Ethiopia 11 years ago, is widely thought to belong to
the first hominid genus — making it among the earliest
human ancestors after Man’s family tree split from the
chimpanzees. It would have looked more like a
chimpanzee than a modern human, but has several
characteristics that marks it out as a member of the
evolutionary lineage that led ultimately to Homo
sapiens.

The creature’s remains show clearly that it walked on
two legs, rather than crouching on all fours like a
modern ape, and it has diamond-shaped upper canine
teeth that are more reminiscent of a human being’s
than the V-shaped canines of chimps.

Analysis of the new fossils, details of which are
published today in the journal Nature, has already
provided scientists with fresh insights into
Ardipithecus’s habitat and way of life.

Other finds at the site where the specimens were
unearthed show that it lived alongside animals,
including antelopes, rhinoceroses, monkeys, giraffes
and hippopotamuses.

The region of northern Ethiopia was significantly
wetter than it is today and Ardipithecus would have
lived in a mixed environment of forest and grassland.
Scientists are continuing to investigate which habitat
the ancient hominids preferred.

“A few windows are now opening in Africa to glance
into the fossil evidence on the earliest hominids,” Dr
Semaw said. “We now have more than thirty fossils from
at least nine individuals dated between 4.3 million
and 4.5 million years old.”

The fossils were found in a site known as the Gona
Study Area, which previously has yielded some of the
most remarkable finds in human prehistory. It is one
of only two sites to have yielded examples of
Ardipithecus ramidus — the other is in Kenya — and
later finds there show that hominids were making tools
as long as 2.5 million years ago.

Hominids are generally thought to have diverged from
chimpanzees between six million and seven million
years ago, and a primitive form of Ardipithecus
ramidus, called Ardipithecus ramidus kabbada, has a
claim to be the earliest known human ancestor, living
about 5.8 million years ago.

The new fossils consist of more than 30 fragments of
bones and teeth, including parts of one upper and two
lower jaw bones with teeth still intact.