The bible tells us that Adam, the first human, was born about 6000 years ago. Many think that mankind is much older. I found this article on the subject. What is your opinion on this?
Humans may be 4m years old
27Apr03
A NEW dating technique suggests that a human-like fossil skeleton found in South Africa was buried about four million years ago, which makes it one of the oldest known hominid discoveries.
That's one million years earlier than previously thought.
The nearly complete skeleton came from the Sterkfontein caves that contain rich deposits of remains from the pre-human branches of the ancestral tree that led to modern humans. The bones are identified as a type of Australopithecus, an extinct form of pre-humans.
Skeleton fossils unearthed in 1997 were age dated at about three million years using a technique that measured the changes in the Earth's magnetic field geochemically recorded within rocks found with the fossils. The results have been disputed by experts who say the method was not precise.
In the new effort, researchers, led by Darryl Granger and M.W. Caffee of Purdue University, measured the decay of isotopes in cave sediments to establish the older ages. A report on their study appears tomorrow (Friday April 25) in the journal Science.
The new technique is based on chemical changes in elements caused by cosmic rays. The bombardment of cosmic rays creates unstable isotopes of beryllium and aluminum, both of which decay at a known rate. The older a sediment is, the more isotopes it acquires.
When the sediments are buried by an earth movement, the cosmic ray bombardment stops, but the isotopic decay continues.
Granger said that the cave is carved by water out of dolomite and cherte rock. Over time, both the fossils and fragments of quartz crystals that were on the surface were washed into the cave and deposited together. Once the quartz is inside the cave, it is no longer being hit by cosmic rays.
"That sets the clock," said Granger.
He said by measuring the isotopic decay in the quartz, the researchers could establish when both the fossils and the quartz were deposited.v The other co-authors of the study are T. C. Partidge and R. J. Clarke, both of the University of the Witwatersrand in Johannesburg, South Africa. Partridge and Clark did the earlier studies on the Sterkfontein fossils.
Australopithecus is an extinct hominid species that lived from about four to two million years ago. Lucy, a famed pre-human fossil find found in Ethiopia, was identified as a type of Australopithecus. The new age-dating technique suggests that the fossils from Sterkfontein Cave are even older than Lucy.
Granger said only an Australopithecus fossil found in Kenya was older than the remains from the South African cave.
However, some researchers said in Science that the specimens used by Granger and Caffee may have been contaminated by debris that was not deposited at the same time as the fossils.
Henry Schwarez of McMaster University in Hamilton, Canada, said in Science that the collapsed cave ceilings may have dropped sediments into the area where the fossils were found and thus distorted the age-dating results. Schwarez said the Purdue researchers needed to test the technique using sediments from South African caves of a known age.
Granger said the age-dating technique was not affected by sediments from inside the cave. He said the cave minerals were distinctly different from the quartz washed in from the surface. The material from the cave walls and ceiling was separated from the quartz before the isotopic measurements were taken, he said.
This report appears on news.com.au.