When did modern humans first arrive in Asia? Skull pieces could hold clues. (+video)
An anatomically modern human skull uncovered in Laos's 'Cave of the Monkeys,' could shed light on human migration patterns out of Africa.
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Archaeological evidence and genetic data suggest that modern humans rapidly migrated out of Africa and into Southeast Asia by at least 60,000 years ago. However, complicating this notion is the notable absence of fossil evidence for modern human occupation in mainland Southeast Asia, likely because those bones do not survive well in the warm, tropical region.
Now a partial skull from Tam Pa Ling, "the Cave of the Monkeys" in northern Laos helps fill in this mysterious gap in the fossil record. [See Photos of "Monkey Cave" Fossils]
"Most surprising is the fact that we found anything at all," researcher Laura Lynn Shackelford, a paleoanthropologist at the University of Illinois, told LiveScience. "Most people didn't think we'd find anything in these caves, or even in the region where we're working in mainland Southeast Asia. But we're stubborn, gone where no one's really looked before, or at least in almost a century."
Rough terrain, persistent scientists
The fossils were discovered in 2009 in the limestone cave, which is located at the top of the Pa Hang Mountain 3,840 feet (1,170 meters) above sea level.
"The cave is surrounded by lots of papaya and banana trees, so a troop of monkeys likes to come and forage there, therefore its name," Shackelford said.
There were many challenges working in this area.
"It's incredibly difficult to access the site — it's only 150 miles (240 kilometers) from the capital, but it takes us two days to drive there because of the rough terrain," Shackelford said. "We have to hike up the side of a cliff, do a bit of rock-climbing to get to the mouth of the cave, and then going in, we have to go 60 meters (200 ft) down a slope of wet clay. We also have to carry a generator and lights with us to see in the cave. We have to push pigs out of the way to get through the jungle — there are just pigs wandering around there." [Amazing Caves: Photos of Earth's Innards]
"Every bit of clay has to be removed and taken back up by hand, trowel and bucket, so work is incredibly slow," she added. "We only go in the dry season in the winter, so we don't really have to deal with insects and snakes — well, we did have snakes fall into the pit while excavating. And in the cave, we've had more than our fair share of spiders and bats."
Oldest bones of modern humans
No artifacts were found at the site, nor were signs of human occupation.