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.
Thailand’s “Siam Ape,” and specimens found in neighboring Myanmar, are larger and more advanced than the minuscule Dawn Monkey, Beard said. These fruit-and-seed eaters were closer to a gibbon’s size and weight, perhaps about 1.5 feet tall and weighing about 15 pounds.
“Siamopithecus [the Siam Ape] is one of several Asian fossils that helps locate the likely birthplace of anthropoids as being somewhere in Asia, maybe Thailand, maybe somewhere nearby,” Beard said.
“The fossil record,” he said, “really isn’t sufficient to make a more precise statement than southern Asia or southeastern Asia as the likely epicenter.”
The Asia origins theory, Beard said, is now endorsed by about 80 percent of paleontologists familiar with the debate. Others claim that scientists have discovered too few good-sized, intact bone fragments to support the assertion.
But the search for more “missing links” in Southeast Asia is waylaid by language barriers and scant government funding for the region’s government researchers.
Yaowalak is Thailand’s only paleontologist searching for more evidence of these transitional primates. Her facilities are basic. The lab in her Bangkok office building was converted to administrative quarters and she now examines fossils on a cluttered tabletop.
Lacking sophisticated scanning equipment, she recently brought a newly discovered fossil to a nearby hospital and offered to pay for an MRI scan. The staff turned her away. “I guess they thought I was wasting their time,” she said.
Yaowalak’s superiors only expect her to publish findings in Thai. Getting published in English-language journals — the medium for exposing advancements to the world — requires writing up findings to the best of her abilities and then forwarding them to sympathetic foreign colleagues, who fix her language errors for free.
This tedious process helps explain why the Siam Ape, discovered in 1996, was only published last year in the “Anatomical Record,” a journal certifying evolutionary discoveries. “A full scientific translation can cost $100 per page,” Yaowalak said. “I just don’t have money for that.”
More remains of our simian ancestors are out there, she said, but they remain difficult to reach.
Many are beneath the Gulf of Thailand, the result of sea level fluctuations and tectonic shifts, she said. In the Siam Ape’s era, Southeast Asia was a long crescent-shaped curl of land seamlessly connecting what is now Indonesia and the Philippines. As these land masses drifted apart, these primate habitats sank beneath the sea, she said.
Even the Siam Ape’s bones would have eluded discovery had Yaowalak not realized coal miners fortuitously exposed fossil-rich layers deep beneath the soil. The mine is now closed off and filled with water.
The next-closest region flush with anthropoid fossils lies inside Myanmar, in the remote Bagan region forbidden to most foreigners by the country’s military junta. Beard, traveling with special permission, has discovered 38-million-year old bones there from a creature not unlike the Siam Ape.
Yaowalak, along with a host of European researchers, has also ventured to this Myanmar province several times in hopes of finding similar fossils. Along the way, when jeeps can’t ply the primitive dirt roads, they travel on elephantback.
“There are lots of deposits out there,” Yaowalak said. “We just have to keep looking. You have to walk with a wish, a wish to find something important, and a lot of luck.”