A partial skull retrieved from a cave in northern Israel is shedding light on a pivotal juncture in early human history when our species was trekking out of Africa to populate other parts of the world and encountered our close cousins the Neanderthals.
Scientists said on Wednesday the upper part of the skull, the domed portion without the face or jaws, was unearthed in Manot Cave in Israel's Western Galilee. Scientific dating techniques determined the skull was about 55,000 years old.
The researchers said characteristics of the skull, dating from a time period when members of our species were thought to have been marching out of Africa, suggest the individual was closely related to the first Homo sapiens populations that later colonized Europe.
They also said the skull provides the first evidence that Homo sapiens inhabited that region at the same time as Neanderthals, our closest extinct human relative.
Tel Aviv University anthropologist Israel Hershkovitz, who led the study published in the journal Nature, called the skull "an important piece of the puzzle of the big story of human evolution."
Previous genetic evidence suggests our species and Neanderthals interbred during roughly the time period represented by the skull, with all people of Eurasian ancestry still retaining a small amount of Neanderthal DNA as a result.
"It is the first direct fossil evidence that modern humans and Neanderthals inhabited the same area at the same time," said paleontologist Bruce Latimer of Case Western Reserve University in Cleveland, another of the researchers.
"The co-existence of these two populations in a confined geographic region at the same time that genetic models predict interbreeding promotes the notion that interbreeding may have occurred in the Levant region," Hershkovitz said.
The robust, large-browed Neanderthals prospered across Europe and Asia from about 350,000 to 400,000 years ago, going extinct sometime after Homo sapiens arrived.
Scientists say our species first appeared about 200,000 years ago in Africa and later migrated elsewhere. The cave is located along the sole land route for ancient humans to take from Africa into the Middle East, Asia and Europe.
Latimer said he suspects the skull belonged to a woman although the researchers could not say definitively.
The cave, sealed off for 30,000 years, was discovered in 2008 during sewage line construction work. Hunting tools, perforated seashells perhaps used ornamentally and animal bones have been excavated from the cave, along with further human remains.