Some periods of human prehistory lack a substantial fossil record in key geographic locations, making it difficult to confirm genetic evidence of modern human migrations. One such crucial period was when the earliest modern humans migrated from East Africa after having originated there 150,000 years ago. Genetic analysis shows that populations left this area between 65,000 and 25,000 years ago, spreading elsewhere in Africa, to Europe, and eventually, around the world. Although plenty of fossils have been discovered in this time period in Europe and North Africa, nothing had turned up in Africa south of the Sahara Desert.
But just such a specimen turned out to be already available. Using a new dating technique called luminescence, a team led by Frederick Grine of Stony Brook University dated for the first time a skull found in 1952 in a dry riverbed in South Africa. They learned the skull, known as the Hofmeyer skull, was 36,000 years old, filling this gap in the African fossil record.
The Hofmeyer skull was found in a dry riverbed and not an archaeological site and no other bones or artifacts were found in the area. Researchers had been unsuccessful in obtaining a radiocarbon date because the skull lacked sufficient collagen. Using a new dating technique that combined luminescence and uranium-series dating methods, researchers were able to estimate the age of the skull by testing the sediment within the skull cavity.
- When and where did the first modern humans originate?
- What evidence is there that these humans migrated to Europe, Asia, and Africa between 65,000 and 25,000 years ago?
- How did the new dating technique help in identifying the age of the Hofmeyer skull?
- Of what importance is the dating of the Hofmeyer skull’s age?
Assign a small group of students to further research the various dating techniques and report their findings to the rest of the class.