Research Confirming Modern Humans Migration from Sub-Saharan Africa Led by Stony Brook Professor

STONY BROOK, N.Y. - A newly dated human skull discovered over fifty years ago near the town of Hofmeyr, in the Eastern Cape Province of South Africa, finally provides critical corroboration of genetic evidence indicating that modern humans originated in sub-Saharan Africa and migrated about this time to colonize the Old World. The finding was published on January 12th in Science magazine by an international team of scientists led by Frederick Grine, from the Departments of Anthropology and Anatomical Sciences at Stony Brook University.

Dr. Grine highlighted that, "This is the first fossil evidence that we have from southern sub-Saharan Africa that pertains to modern human origins."

The South African skull, discovered in 1952 near the town of Hofmeyr in Eastern Cape Province , had resisted previous attempts to be dated. Traditional radiocarbon (C-14) dating of the Hofmeyr skull was not possible because the carbon had been leached from the bone while it was buried in sediment. Thanks to a new approach to dating developed by Grine team member Richard Bailey and his colleagues at Oxford University , its significance became apparent only recently.

Dr. Grine and his colleagues were able to combine two techniques and date the skull by determining when the sand grains in its brain case were last exposed to sunlight. Measurements of radioactive isotopes in the sediment, combined with a sophisticated radiation transport model using data from a CT scan of the skull, allowed them to calculate the yearly rate at which radiation had been delivered to the sand grains. From this, it was determined that the Hofmeyr skull was buried just over 36,000 years ago. At this age, the skull fills a significant void in the human fossil record of sub-Saharan Africa .

Paleontological evidence from sub-Saharan Africa has long been devoid of human fossils from the period between about 70,000 and 15,000 years ago, a critical period in human evolutionary history. Until now, only genetic evidence has lent support to the "Out of Africa" theory, while big gaps in the fossil record left the door open to the competing hypothesis that: Modern humans are more gradual mix of populations that originated and interacted across multiple regions of Africa, Europe and Asia.

By dating the skull to 36,000 years ago, the team has provided a key piece of evidence to the "Out of Africa" theory of modern human origins. The popularly known theory portrays humans as descendents of a population that arose in sub-Saharan Africa and dispersed in successive waves. Grine and his team compared the skull from Hofmeyr with contemporaneous Upper Paleolithic skulls from Europe , and skulls of living sub-Saharan Africans, including the Khoe-San (Bushmen).

Because the Khoe-San are represented in the recent archeological record of South Africa , they were expected to have close resemblances to the South African fossil. Instead, the South African fossil has a very close affinity with the European Upper Paleolithic specimens, and is quite distinct from recent sub-Saharan Africans . Grine and his colleagues were surprised by the degree of similarity between a fossil skull from the southernmost tip of Africa and similarly ancient skulls from Europe . This predicts that humans like those that inhabited Eurasia in the Upper Paleolithic should be found in sub-Saharan Africa around 36,000 years ago.

"The Hofmeyr skull gives us the first insights into the morphology of such a sub-Saharan African population, which means the most recent common ancestor of all of us -wherever we come from," said Dr. Grine.

Pictured: The Hofmeyr skull (Frederick E. Grine)