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Tracing humanity’s ancestors back to Asia, not Africa.
BANGKOK, Thailand — It first appeared to the paleontologist as a dull glint, half-submerged in a coal pit, but winking back sunlight nonetheless.
“Its enamel was a bit reflective in the dirt,” said Sasidhorn Khansubha, a government-employed Thai paleontologist. She and the country’s foremost primate fossil expert were picking through a coal mine on a dig in Krabi, along the southern Thai coast.
“I had no idea if it was even important, so I handed it to the specialist,” Sasidhorn said. “She was shocked and thrilled. It’s what we’d sought for so long.”
They’d discovered a jawbone, half-crushed and stained through with coal grime. After analysis, it revealed the existence of the “Siam Ape,” a 15-pound simian that roamed Asia’s ancient jungles 35 million years ago. If leading paleontologists are correct, this Asian primate could be an ancestor to us all.
This fossilized jawbone of an extinct "Siam Ape" suggests that humankind's evolutionary precursors evolved in Asia, not Africa.
“For a long time, people have said early anthropoids [higher-order primates] developed in Africa,” said Yaowalak Chaimanee, a senior fossil specialist with Thailand’s Department of Mineral Resources. “We propose the real origin is Asia.”
Paleontologists almost universally agree that humans evolved in Africa through a split from apes about 5 million years ago.
Dialing back our ancestry a step further, however, is more tricky.
For more than a century, researchers have believed that Africa gave rise not only to humans but also to our precursors: advanced primates. A newer wave of fossil finds in Asia, however, suggests this happened somewhere in Southeast Asia.
At some point, Yaowalak said, these higher-functioning primates migrated to Africa and then further evolved into hominids: the socially complex, upright-walking biological order that includes gorillas, chimps, orangutans and human beings.
This Asia origins theory — still debated by some leading paleontologists — took off with the 1995 discovery of the fossilized “Dawn Monkey” in central China. The palm-sized monkey lived 45-million years ago, roughly 12 million years before the oldest anthropoid found in Africa.
Though quite primitive, the Dawn Monkey is now considered one of the oldest primate “missing links” with more-advanced features, said Christopher Beard, the Carnegie Museum of Natural History paleontologist who oversaw the fossil’s discovery. (It was technically found by a pickaxe-wielding Chinese farmer that Beard employed.)
These transitional creatures are a cross between the most ancient monkeys — slow-moving, nocturnal tree-dwellers — and the larger, upright beasts like chimps. Over time, their brains grew bigger and their eyes became more forward-facing, Beard said.