Human ancestors unearthed
2005-01-20 07:12
Paris - Palaeontologists say they have found a fossil haul from at least nine hominids who lived in eastern Africa more than four million years ago in the early chapters of human history.
The discovery was made at As Duma in Ethiopia's Afar region, near the border with Djibouti, they report in Thursday's issue of Nature, the weekly British scientific journal.
The find - mainly teeth, pieces of jaw, hand and feet - are dated as between 4.32-4.51 million years old and belonging to Ardipithecus ramidus, an enigmatic hominid whose remains were first found in the area in the early nineties.
A ramidus has a strong claim to being the oldest forerunner of modern man ever to be identified. In 2001, one specimen found in the Afar was carbon-dated at around 5.2 million years old.
Explorers elsewhere have separately found fragmentary hominid remains that, they say, predate A ramidus, although these claims have been hotly disputed.
One is "Toumai", found by a French team in Chad, which is put at between six and seven million years old, and the other is "Orrorin", found in Kenya in 2000, estimated at some six million years old.
The authenticity of A ramidus has not been questioned, although very little is known as to his size and how he lived.
The riddle remains
In the latest discovery, the scientists found the remains of monkeys, cow-like grazing animals and a creature called a mole rat, a rodent which lives in burrows in the savannah.
More intriguingly, they analysed the carbon isotopes of the soils of the Afar, which points to the kind of vegetation that grew there millions of years ago.
The evidence points to a landscape that is very different from the dry, baked rift valley of today.
It was "a mosaic of environments" covered by woods and grassy woodlands, with lakes, swamps, springs and streams and local volcanic hotspots, the carbon findings suggest.
Some anthropologists say the habitat question is vital for understanding the rise of man.
One theory is that the earliest hominids, as part of their genetic break with chimpanzees, were prompted to walk upright because they lived in the savannah, the wide African plain.
By standing up, they gained height in this flat, open landscape, which was an advantage for spotting prey and predators.
But the riddle remains unresolved.
"Only further evidence that more tightly associates the hominids (and other fauna) with the varied local environments will reveal the habitat preferences of these early hominids," the authors, led by Sileshi Semaw, of the CRAFT Stone Age Institute at Indian University, admit.