Since the sequencing of the human genome, scientists have opined that there was one migration out of Africa that populated the rest of the world. Recently, a 90 year old lock of hair collected by a British anthropologist, Alfred Cort Haddon, from a young male Australian Aborigine proves that there was at least two migrations and perhaps more.
A Lock of Hair Unlocks the Past
Professor Eske Willerslev, a paleogenecticist at the University of Copenhagen, Denmark, discovered from this lock of hair that the Aboriginal Australians are the descendants of the first humans to leave Africa. Those first humans are thought to be the ancestors of the Koisan, sometimes referred to as “Bushmen”, of the Kalahari desert in South Africa. The migration of these early humans was accomplished over land and water about 60,000 years ago, thousands of years before the the ancestors of modern Asians made the journey out of Africa.
DNA May be more Reliable than Archeological Finds
Many previously cherished notions about human migration are changing. Traditionally, paleontologists have thought in terms of one migration out of Africa which formed the basis for later human populations around the earth. With recent DNA findings, however, this view has been modified to at least two migrations, perhaps more. Previously, paleontologists relied on the findings of human remains. The oldest modern human remains found in Africa date to 50,000 years which established a now outdated time frame of migration. As a result of recent discoveries, archeological discoveries of human remains may now be considered less reliable in dating migrations than DNA. Also tending to disprove the single migration theory is that stone tools have been found in India that are dated before 50,000 years. The finds of the earlier stone tools also demonstrates multiple migrations.
Genome Sequencing of the 90 Year Old Hair
As a result of interbreeding between modern Australian Aborigines and European settlers, Professor Willerslev thought that he wouldn’t be able to sequence the DNA accurately using the genome of modern Aborigines. The DNA sequencing of the lock of hair proves that the ancestors of the owner of this lock of hair left Africa more than 60,000 years ago. According to Professor Willerslev, the ancestors of contemporary Europeans and most Asians probably dates to less than 40,000 years ago.
Aborigines May Also Be Descended from Denisovans
More surprisingly, the young Aborigine donating the lock of hair was also descended from an archaic human population known as the Denisovans. The Denisovans, close relatives to both modern humans and Neanderthals, splitting about 500,000 years ago, were discovered recently from a finger bone found in the Altai mountains of Siberia. The Denisovans branched from the human family tree about 1 million years ago, making this group earlier than Homo Erectus, the pre- human that spread out of Africa to much of the world about 1.9 million years ago. This discovery was made by researchers led by Mark Stoneking of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who think that Denisovan ancestry is found in 33 Asian and Oceanian populations. Until Professor Willerslev’s discovery, Papua New Guineans were thought to be the only population with Denisovan genes.
Collateral Evidence of Earlier Settlement in Australian
Supporting DNA findings of multiple migrations, Alan Redd, a biological anthropologist at the University of Kansas in Lawrence, says that the peopling of Australia may be more complicated than a single migration. He notes that Dingoes, the Australian wild dog, were brought to the island by humans arriving in the last 5,000 years.
Other Recent DNA Findings
In other DNA studies, Eske Willerslev has also identified that the Saqqaq of Northern Greenland are related to the Chukchi of Siberia. Additionally, his DNA studies have also shown that rather than catching and tagging modern animal species, one need only dig in the dirt to capture DNA left by animals in the top 10 centimeters of soil if scientists want to know what animals have populated certain areas. By analyzing the DNA in the dirt, scientist can learn what animals lived in a certain location and how many of the them lived there. Animals traveling through an area leave hair, flakes of skin and feces, all of which are sources for DNA. As a result, Willerslev’s work establishes a new protocol for scientists in ascertaining animal populations.
The field of DNA research is moving rapidly and dispatching many previous notions held as absolute truths.
Sources: "Ecologists dig deep for DNA", Science Magazine September 23, 2011
"Possible new human ancestor found in Siberia" Reuters, March 24, 2010
"First Aboriginal genome sequenced", Nature Magazine, September 22, 2011
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