杏吧原创

The early history of our species needs to be rewritten 鈥� again. A human jawbone from a cave in Israel has proven to be at least 177,000 years old, indicating that聽Homo sapiens聽left its African birthplace at least 50,000 years earlier than thought. The find solves several mysteries of human evolution, but also creates new ones.

Most scientists agree that our species evolved in Africa within the last few hundred thousand years. It was not until around 70,000 years ago that we trekked into Asia, and聽from there to every continent.

However, there were earlier forays out of Africa. Until now, the oldest widely accepted evidence was from sites at Skhul and Qafzeh in Israel, dating to around 120,000 years ago. These outposts are generally thought to have been 鈥渄ead ends鈥�, meaning that the people who lived there have not left any living descendants. Such outposts probably either withered or got wiped out by later human migrations from Africa.

狈辞飞听聽of Tel Aviv University in Israel and his colleagues have pushed the date of our first extra-African excursion back by at least 50,000 years.

滨苍听聽on the slopes of Mount Carmel in Israel, around 7 kilometres from the other sites, they have found the upper jawbone and teeth of a human. Three independent laboratories have dated the remains, using three techniques, and all agree that they are between 177,000 and 194,000 years old.
鈥淭he hominins from Skhul were considered the first outside Africa,鈥� says Hershkovitz. 鈥淣ow we know it is not the case.鈥� He suspects the people living at Skhul and Qafzeh are descended from those at Misliya, and that the area was continuously settled for tens of thousands of years.

Nice place to live

The area around Misliya Cave was a good choice of home, says team member聽聽of the University of Haifa, Israel. 鈥淚t lies high up in Mount Carmel. It鈥檚 about 90 metres above the sea level of today, but at the time it must have been 200 to 250 metres above sea level. They were overlooking the coast.鈥� So both pleasant and with seafood to hand.

Like all hominins at that time, they were hunter-gatherers. 鈥淭hey hunted mainly gazelles, probably with flint points that they fabricated,鈥� says Weinstein-Evron. They also ate aurochs 鈥� the wild ancestors of domestic cattle 鈥� wild goats, hares, turtles and even ostrich eggs. There is also evidence that they ate plant material, such as tubers, and that they made bedding or matting. 鈥淭hey were smart,鈥� she says.

Experts contacted by聽New 杏吧原创聽have broadly accepted the findings. 鈥淭he first forays out of Africa were clearly earlier than previously thought, and it may be that there were multiple dispersals鈥� says聽聽of the Natural History Museum in London, UK.

The Misliya jawbone may not even be the oldest聽H. sapiens聽outside Africa, adds Galway-Witham. 鈥淕enetic studies of Neanderthal DNA indicate that there was a period of interbreeding between聽H. sapiens聽and Neanderthals between about 460,000 and 219,000 years ago,鈥� she says. Neanderthal remains have only ever been found in Europe and Asia, so any such interbreeding presumably occurred outside Africa.

A year ago, the Misliya findings might have been more controversial. At that time the oldest confirmed聽H. sapiens, from Omo Kibish in Ethiopia,聽. However, in June 2017 researchers showed that skulls found at Jebel Irhoud in Morocco were primitive聽H. sapiens, and聽were at least 315,000 years old.

鈥淥ur species is much older than we previously thought,鈥� says Hershkovitz. So it makes sense that we also left Africa at an earlier time.

A history rewritten

Some aspects of our prehistory now make more sense, while others have become more mysterious.

One that now looks comprehensible is the settlement of Australia. In July 2017, archaeologists found evidence that humans were living there 65,000 years ago, much earlier than thought (). That was difficult to explain if humans only left Africa 70,000 years ago, but makes sense if there was an earlier exit.

Similarly, there have been many claims that modern humans were living in Asia 鈥� particularly China 鈥撀�around 100,000 years ago, or even earlier. Many archaeologists have been sceptical, but the idea now looks much less outlandish.

However, some things still don鈥檛 quite fit. One Chinese specimen,聽the Dali skull, has been reliably dated to 260,000 years ago and appears to be an archaic聽H. sapiens. It is much older than the Misliya fossil, suggesting an even earlier jaunt out of Africa. However, it is still compatible with the 315,000-year-old fossils at Jebel Irhoud.

Changing brains

A second paper, published on Wednesday, indicates that these migrations out of Africa happened while our brains were still changing shape.

聽of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and his colleagues examined how human braincases changed shape over evolutionary time. Overall, they became less elongated and more globular.

Neubauer looked at three groups of fossils. The oldest were 300,000 to 200,000 years old. Their braincases 鈥渓ook really archaic鈥�, he says. A second group from around 100,000 years ago 鈥渓ook more modern but still different from present-day humans鈥�. The final set are all 鈥測ounger than 35,000 years old鈥� and are 鈥渨ithin the variation of present-day humans鈥�.

鈥淭he data suggests the modern shape was established at some point between 100,000 years ago and 35,000 years ago,鈥� says Neubauer. This accords with archaeological evidence that humans began behaving in much more complex, 鈥渕odern鈥� ways 40-50,000 years ago, a period called the Great Leap Forward. However, the more modern brain shape was evidently not needed to make the move out of Africa.