Research Suggests Single African Origin Of Humans

Thursday, July 19, 2007

Homo Erectus

The study combined information about genetic variation in humans with skull measurements from across the world.

To date, scholars have been divided about how anatomically modern humans originated. Some argue that they sprang from the same single point in Africa and migrated across the world, while others believe that different populations evolved independently from homo erectus to homo sapiens in different areas.

The Cambridge researchers studied the genetic make-up of people around the world and the measurements of more than 60,000 skulls kept in academic collections.

Their research appears to disprove at least one of the arguments in favor of multiple origins. The findings show that populations share more genetic similarities the further they are from Africa, and that this is mirrored by a decrease in the variety of physical attributes.

Such a pattern would indicate that all populations come from the same shared group of ancestors who gradually migrated further away from Africa over thousands of years. Their genetic and physical diversity would have been narrowed down by bottlenecks, or events that temporarily reduced the population during migration, such as natural disasters.

In parallel with the genetic data, the skull measurements showed that not only was physical variation highest among the sample from south-east Africa, but that it decreased at the same rate as genetic data the further away the skull was.

Lead researcher, Dr Andrea Manica from the University's Department of Zoology explained: The origin of anatomically modern humans has been the focus of much-heated debate. 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.

To ensure the validity of their single origin evidence, the researchers attempted to use their data to find non-African origins for modern humans. Researcher Dr Francois Balloux explained: To test the alternative theory for the origin of modern humans we tried to find an additional, non-African origin, but this simply did not work, suggesting a single point of origin.

The research was funded by the Biotechnology and Biological Sciences Research Council (BBSRC).

Source: Cambridge University