Ian McDougall of Australian National University (ANU), Frank Brown of the University of Utah and John Fleagle of Stony Brook University, report their findings in the Feb. 17 issue of the journal Nature.
The fossils, from near the town of Kibish, are far more ancient than researchers originally suspected and nearly 40,000 years older than skulls from Herto, Ethiopia, the previous record holders.
The Kibish hominids—dubbed Omo I and Omo II—were once entombed in sediments on opposite sides of the Omo River in southern Ethiopia. By applying modern radiometric dating techniques and a careful study of sediments and fossils, the researchers linked the Omo hominids, true Homo sapiens, to a single period in time.
“Some have considered Omo I to be more ‘modern?in appearance,?says Mark Weiss, the NSF officer who oversaw this research. “It’s fascinating that we can now see that these two rather different individuals were living at the same time and in the same region,?he adds.
The researchers also discovered the fossil-rich strata can be linked to sapropels, sediment layers found in the eastern Mediterranean, which, along with ice cores, tree rings and annual lake deposits, are part of the geological record scientists study for indications of climate change. The team believes the Africa-Mediterranean correlation ties both regions to moister climates long ago, yielding another method to understand climate history in that part of the world.
“The correlation between the Kibish deposits and the Mediterranean sapropels
Source:National Science Foundation