A new Myanmar fossil primate, Ganlea megacanina, suggests the common ancestor of humans, monkeys and apes evolved from large-toothed primates in Asia and not Africa, according to new research published in the latest Proceedings of the Royal Society B.
If Myanmar, formerly called Burma, is confirmed as being the ancestral homeland of higher primates, or close to it, the discovery points to a circuitous migration route for some early primates, which must have gone to Africa and then come back to Asia.
Christopher Beard, lead author of the study, told Discovery News that the common ancestor to today's humans, monkeys and apes "would have lived in Asia."
"At some point later in time, probably only a few million years after Ganlea was alive, one or more primitive anthropoid primates, which would have been descendants of an earlier Asian ancestor, made their way from Asia to Africa," explained Beard, a Carnegie Museum of Natural History paleontologist.
"There, they continued to evolve, and some of them eventually became modern Old World monkeys, apes and humans," he added. "Living monkeys and apes like the orangutan that inhabit Asia returned there after evolving for millions of years in Africa."
Tale of the teeth
Beard and his international team came to this conclusion after studying the newly identified fossil primate, which lived 38 million years ago in a tropical floodplain similar to today's monkey-filled Amazon Basin of South America. The study was conducted under difficult conditions in rural areas of Myanmar.
Heavy dental abrasion indicates Ganlea possessed enlarged canine teeth that it used to pry open the hard exteriors of tough tropical fruits to extract interior nuts and seeds. Among living and fossil primates, only anthropoids — higher primates — feed in such a manner.
"Ganlea has the right kind of anatomy, especially its monkeylike jaws and teeth, to be an animal that was very close to the common ancestor of living monkeys, apes and humans," Beard said. "Put simply, if it looks like a duck and walks like a duck, it's probably a duck, or in this case, a monkey!"
Questions about ‘Ida’
The discovery may take the spotlight off "Ida," an ancient lemurlike animal from Germany that Jens Franzen of the Natural History Museum of Basel and his colleagues described earlier this year. Franzen and his team wrote that Ida was "not simply a fossil lemur, but part of a larger group of primates" that they and other scientists theorized could have led to the emergence of anthropoids.
If additional research supports the "Out of Asia" ancestry of higher primates, Ida and other ancient lemurlike animals would then be placed on the lowest branch of the primate family tree.
This branch, according to Beard, "ultimately leads to living lemurs, which are the most distantly related primates to us that remain alive today."
Beard still believes modern humans descended from an African population that lived around 200,000 years ago. "But," he said, "some extinct species of humans, such as the 'hobbit' Homo floresiensis, almost certainly evolved in Asia."
The "Out of Asia" finding comes on the heels of another surprise announcement that could affect the primate family tree.
Jeffrey Schwartz, a University of Pittsburgh anthropologist, and his colleagues believe humans most likely share a common ancestor with orangutans, relegating chimpanzees and gorillas to a separate group. They came to this conclusion after studying hundreds of physical characteristics of various primates, including humans.
Beard hopes future government funding will allow for continued research on primates and their ancient relatives, which he said has the added benefit of promoting scientific and cultural exchanges between people "that otherwise would not have much contact with each other."