Max_Headroom
Well-Known Member
- Joined
- 10 Oct 2011
- Messages
- 358
Dawn of human race uncovered
16:07 11 June 2003 by James Randerson
Three fossil skulls from Ethiopia have been revealed as the oldest human remains yet discovered.
The 160,000-year-old finds plug an important gap in the fossil record around the time our species first appeared and provides strong new evidence that Homo sapiens originated only in Africa.
"These are landmark finds in unravelling our origins," says Chris Stringer, at the Natural History Museum in London, and a champion of the 'Out of Africa' hypothesis. He believes modern humans evolved in Africa before migrating across the globe, rather than evolving in parallel in different places.
"The problem with the African record is that it has been really sketchy," says Tim White at the University of California, Berkeley, who led the team that made the discoveries. There are good human fossils from 100,000 years ago, he adds, but from then back to 300,000 years ago the remains are either highly fragmented, poorly dated or both.
In contrast, the newly revealed skulls have precise dates thanks to the fragments of volcanic rocks found with the fossils. When rocks cool, they begin to accumulate argon gas from the decay of a potassium isotope. Analysing the gas gives the rock's age, in this case 154,000 to 160,000 years old.
Neanderthal influence
Homo sapiens appeared sometime between 100,000 and 300,000 years ago, and controversy has raged over whether there was a single African origin or whether other hominids such as Homo erectus and Neanderthals made a significant contribution to the evolution of modern humans by interbreeding.
The latest fossils provide substantial support for the Out of Africa camp, but proponents of the alternative 'multi-regional' hypothesis do not believe the argument is over. "This could easily be one of the ancestors of modern Europeans, but I don't believe it is the only ancestor," says Milford Wolpoff at the University of Michigan in Ann Arbor.
The skulls look almost human, but retain some slight primitive features and so the team has given them their own subspecies - Homo sapiens idàltu. The skulls, from two men and a child, are also very large by human standards suggesting the adults cut an imposing figure.
The recovery of the fossils began in 1997, near the Ethiopian village of Herto, when White stumbled across a fossilised hippopotamus skull. His team eventually recovered skull fragments from 10 humans, along with many stone tools and animal fossils. The child's skull was in over 200 pieces strewn over hundreds of metres and it took two years of painstaking work to reconstruct it.
Ancestor worship
Some of the most intriguing aspects of the skulls are the modifications made after death. One of the adult skulls has parallel grooves around the perimeter cut with a stone tool.
"There's no meat in the places they're finding the cut marks," points out Sally McBrearty, a stone tool expert at the University of Connecticut in Storrs, so they did not result from cannibalism.
The child's skull is also marked and broken edges have been polished. This suggests to White that the skull was carried around after death and buffed up in the process - possibly as part of an ancestor worshipping ritual. This is the earliest evidence that bones were kept by descendants and points to an advanced level of cultural development. Journal reference: Nature (vol 423, p 737)
16:07 11 June 2003 by James Randerson
Three fossil skulls from Ethiopia have been revealed as the oldest human remains yet discovered.
The 160,000-year-old finds plug an important gap in the fossil record around the time our species first appeared and provides strong new evidence that Homo sapiens originated only in Africa.
"These are landmark finds in unravelling our origins," says Chris Stringer, at the Natural History Museum in London, and a champion of the 'Out of Africa' hypothesis. He believes modern humans evolved in Africa before migrating across the globe, rather than evolving in parallel in different places.
"The problem with the African record is that it has been really sketchy," says Tim White at the University of California, Berkeley, who led the team that made the discoveries. There are good human fossils from 100,000 years ago, he adds, but from then back to 300,000 years ago the remains are either highly fragmented, poorly dated or both.
In contrast, the newly revealed skulls have precise dates thanks to the fragments of volcanic rocks found with the fossils. When rocks cool, they begin to accumulate argon gas from the decay of a potassium isotope. Analysing the gas gives the rock's age, in this case 154,000 to 160,000 years old.
Neanderthal influence
Homo sapiens appeared sometime between 100,000 and 300,000 years ago, and controversy has raged over whether there was a single African origin or whether other hominids such as Homo erectus and Neanderthals made a significant contribution to the evolution of modern humans by interbreeding.
The latest fossils provide substantial support for the Out of Africa camp, but proponents of the alternative 'multi-regional' hypothesis do not believe the argument is over. "This could easily be one of the ancestors of modern Europeans, but I don't believe it is the only ancestor," says Milford Wolpoff at the University of Michigan in Ann Arbor.
The skulls look almost human, but retain some slight primitive features and so the team has given them their own subspecies - Homo sapiens idàltu. The skulls, from two men and a child, are also very large by human standards suggesting the adults cut an imposing figure.
The recovery of the fossils began in 1997, near the Ethiopian village of Herto, when White stumbled across a fossilised hippopotamus skull. His team eventually recovered skull fragments from 10 humans, along with many stone tools and animal fossils. The child's skull was in over 200 pieces strewn over hundreds of metres and it took two years of painstaking work to reconstruct it.
Ancestor worship
Some of the most intriguing aspects of the skulls are the modifications made after death. One of the adult skulls has parallel grooves around the perimeter cut with a stone tool.
"There's no meat in the places they're finding the cut marks," points out Sally McBrearty, a stone tool expert at the University of Connecticut in Storrs, so they did not result from cannibalism.
The child's skull is also marked and broken edges have been polished. This suggests to White that the skull was carried around after death and buffed up in the process - possibly as part of an ancestor worshipping ritual. This is the earliest evidence that bones were kept by descendants and points to an advanced level of cultural development. Journal reference: Nature (vol 423, p 737)
