By Steve Connor, Science Correspondent. Sunday Times, 9th November 1997
ALL men can trace their ancestry back to one man who lived 150,000 years ago and whose closest living relatives are a small tribe in South Africa, according to scientists who have spent a decade searching for the original Adam.
Research into the human Y chromosome which sons only inherit from their fathers has pinpointed the time and place where just one man gave rise to the male genetic ingredients of all men alive today.
The geneticists have also located the oldest direct descendants of this Adam, who they say lived alongside an African Eve who was identified in similar studies 10 years ago.
The Khoisan people of South Africa, some with a hunter-gatherer tradition stretching back thousands of years, share most of the genetic traits that first arose when Adam hunted game and collected berries in his African Garden of Eden.
Two independent investigations of minute mutations on the Y chromosome pinpointed the Khoisan people, who are also known as Bushmen or Hottentots, as the only ethnic group to possess so many ancient remnants of the original Adam.
Dr Michael Hammer, a geneticist at the University of Arizona, analysed the Y chromosome of more than 1,500 men selected from ethnic groups around the world and found a clear line of descendent from the African Adam to the present-day Khoisan people.
"One way of looking at this is that the Y chromosome traces back to people who lived in Africa. We have evidence that the Y chromosomes in all men today trace back to one African male at some time in the past," he said. "It is possible that this male was not anatomically modern. He may have been more like Homo erectus, one of our hominid ancestors, but his Y chromosome survived the change in the way we look."
By studying the variety of mutations in the Y chromosome of men alive today, Hammer's team was able to determine how long it has taken these genetic changes to arise and where the original source came from.
He found that the Khoisan, who speak a unique click language, preserved an ancient genetic signal as well as an old cultural heritage. "The oldest branch of the [human family] tree that traces all the way back to Adam is represented today by the Khoisan people," Hammer said. "Something like 20% of the Khoisan men have this old, old Y chromosome. We don't find it at all in European populations and it is present in very low levels, 2% or 3%, in other African groups."
A separate study of Y chromosomes by Dr Peter Oefner, a senior researcher at Stanford University in California, also supports the link between Adam and the Khoisan, who now live in South Africa but whose ancestors probably emigrated from the Rift Valley of east Africa where Homo sapiens is believed to have evolved.
The scientists said the research does not support the biblical story of a single man and woman in a Garden of Eden. "This result does not mean there was ever only one male but rather that a unique mutation occurred, resulting in one son who defined the new [genetic] line and whose male descendants eventually reached a majority in Africa. Some offspring of this lineage left Africa to populate the entire globe," Oefner said.
This news story is based on a short item by Ann Gibbons in the journal Science:- "Y Chromosome Shows That Adam Was an African." Science 278 (31 October 1997), 804-805