Friday, July 20, 2007

Skulls that prove we all came from Africa

The human population arose from a single migration out of Africa 55,000 years ago, which replaced all other humans in Europe and Asia, a study shows.
Scientists have confirmed the "out-of-Africa" model of human origins with a study that combines genetic evidence with physical data from more than 6,000 skulls around the world.
The twin approach has delivered what may turn out to be the killer blow to the rival theory that humans evolved in several regions of the world, said Andrea Manica of the University of Cambridge, who led the study, published in the journal Nature.
"We are convinced of the out-of-Africa hypothesis because the way we did this study gives us an edge we didn't have before," Dr Manica said. "We looked at the genetics and we looked at the skulls and I cannot see what other arguments you can come up with to explain what we have observed."
Studies of DNA and the physical differences between skulls show that human variation diminishes the greater the distance from Africa. This confirms the view that after originating in Africa about 200,000 years ago, anatomically modern Homo sapiens lived on the continent for about 150,000 years before beginning the long trek to Asia, Australia, Europe and finally the Americas.
Other species of humans, such as Homo erectus and Neanderthal man, had already migrated from Africa much earlier in history, but they all became extinct after modern humans arrived in their areas.
The study appears to confirm that interbreeding between modern Homo sapiens and other human species did not occur, or, if it did, it was not on a scale that resulted in any living descendants.
The study also strongly suggests the cradle of modern humanity lies in central or southern Africa, where Homo sapiens arose and spent three-quarters of its history before migrating to the four corners of the globe.
"The origin of anatomically modern humans has been the focus of much heated debate," Dr Manica said. "Our research shows the further modern humans have migrated from Africa, the more genetic diversity has been lost within a population. Some have used skull data to argue that modern humans originated in multiple spots around the world. We have combined our genetic data with new measurements of a large sample of skulls to show definitively that modern humans originated from a single area in sub-Saharan Africa."
Indigenous people living in Australia and South America show the lowest amount of genetic variation as well as differences between the shapes and sizes of their skulls. Meanwhile, the genetic and physical variation between people living in Africa is the greatest anywhere in the world.

1 comment:

Danielle said...

This is a great interest of mine. Thanks for spreading the information. I would suggest the documentaries: Eve, and Walking with Cave Men.

For More of My Modern Musings

2007 Blogathon For and To Resist | July 28th - 48 posts in 24 hours | Support Community Based Progressive Change by Becoming a Sponsor.