Lost Civilization

Veiled beneath the Persian Gulf, a once-fertile landmass may have supported some of the earliest humans outside Africa some 75,000 to 100,000 years ago, a new review of research suggests.

At its peak, the floodplain now below the Gulf would have been about the size of Great Britain, and then shrank as water began to flood the area. Then, about 8,000 years ago, the land would have been swallowed up by the Indian Ocean, the review scientist said.

The study, which is detailed in the December issue of the journal Current Anthropology, has broad implications for aspects of human history. For instance, scientists have debated over when early modern humans exited Africa, with dates as early as 125,000 years ago and as recent as 60,000 years ago (the more recent date is the currently accepted paradigm), according to study researcher Jeffrey Rose, an archaeologist at the University of Birmingham in the U.K.

"I think Jeff's theory is bold and imaginative, and hopefully will shake things up," Robert Carter of Oxford Brookes University in the U.K. told LiveScience. "It would completely rewrite our understanding of the out-of-Africa migration. It is far from proven, but Jeff and others will be developing research programs to test the theory."

Viktor Cerny of the Archaeogenetics Laboratory, the Institute of Archaeology, in Prague, called Rose's finding an "excellent theory," in an e-mail to LiveScience, though he also points out the need for more research to confirm it.

The findings have sparked discussion among researchers, including Carter and Cerny, who were allowed to provide comments within the research paper, about who exactly the humans were who occupied the Gulf basin.

"Given the presence of Neanderthal communities in the upper reaches of the Tigris and Euphrates River, as well as in the eastern Mediterranean region, this may very well have been the contact zone between moderns and Neanderthals," Rose told LiveScience. In fact, recent evidence from the sequencing of the Neanderthal genome suggests interbreeding, meaning we are part caveman.

The Gulf Oasis would have been a shallow inland basin exposed from about 75,000 years ago until 8,000 years ago, forming the southern tip of the Fertile Crescent, according to historical sea-level records.

And it would have been an ideal refuge from the harsh deserts surrounding it, with fresh water supplied by the Tigris, Euphrates, Karun and Wadi Baton Rivers, as well as by upwelling springs, Rose said. And during the last ice age when conditions were at their driest, this basin would've been at its largest.

In fact, in recent years, archaeologists have turned up evidence of a wave of human settlements along the shores of the Gulf dating to about 7,500 years ago.