'It's already clear that we're seeing the basic grade from
which Australopithecus evolved,' he said. 'The real issues about
the earliest hominids are now going to centre on whether we are seeing
the same basic creature in Kenya, Ethiopia, and Chad.'
The most famous Australopithecus fossils are those
of 'Lucy', a female skeleton discovered in Ethiopia during the 1970s. The
so-called australopithecines are widely thought to have led onto the human
lineage. Ardipithecus could therefore represent an earlier step on
the path which led to modern humans, as well as a number of other, extinct
The age of the newly described remains was estimated by
dating volcanic material found in their vicinity.
'A few windows are now opening in Africa [through which
we can] glance into the fossil evidence on the earliest hominids,' Dr
Semaw explained. 'We now have more than thirty fossils from at least nine
individuals dated between 4.3 and 4.5 million years old.'
Another Ardipithecus species, kadabba, lived
in Ethiopia at around 5.77 to 5.54 million years ago. Genetic studies
have suggested a common ancestor for modern apes and humans may have
existed about six million years ago.
Other fossils found at the site show that Ardipithecus
ramidus lived alongside monkeys, mole rats, and cow-like grazing
animals. But the authors add that it is not clear exactly in what sort of
habitat the hominids lived. The area in which the remains were unearthed
would have had features of swamps, springs, and streams, as well as
regions which experienced seasonal droughts.
Professor White discovered the first Ardipithecus
ramidus fossils in the Middle Awash region of Ethiopia with his
colleagues Gen Suwa and Berhane Asfaw.