The challenge of direct dating old human fossils
At the time the site was occupied by early hominins, it would have been a cave, but the covering rock and much sediment were removed by work at the site in the 1960s.
These domains could be extracted and used for open-system U-series dating Firstly, the diffusion–adsorption model could be applied for open-system U-series dating of bones well beyond one million years.
Secondly, a combination of Th/U–Pa/U dating could be applied on bones.
The maps show a complex system of U-migration in and out of the dental tissues.
There are clearly domains in the dentine of the tooth where the Th/U ratios indicate continuing U-accumulation.
View the full list fossils (Omo Kibish, estimated age 195,000 years, and Herto, estimated age 160,000 years), both found in modern-day Ethiopia, East Africa.