Scientists uncover fossils that show why humans did not evolve in Asia 34 million years ago – ABC Online
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The find sheds new light on how the “big chill” forced humans to evolve in Africa. (AFP: David Hecker)
A treasure trove of fossils of six furry critters that inhabited the trees of southern China 34 million years ago is providing a deeper understanding of a pivotal moment in the evolution of primates.
Scientists have discovered the remains of six previously unknown extinct primate species: four similar to Madagascar’s lemurs, one similar to the nocturnal insect and lizard-eating tarsiers of the Philippines and Indonesia, and one monkey-like primate.
Primates are among the most environmentally sensitive of all mammals.
They lived shortly after a dramatic episode of global climate change that brought cooler, drier conditions that triggered the extinction of all primates in North America and Europe and devastated Asia’s primates.
The primate lineage that led to monkeys, apes and people — called anthropoids — originated in Asia with their earliest fossils dating from 45 million years ago.
Only later, about 38 million years ago, did some anthropoids migrate to Africa. It was on that continent 200,000 years ago that humans arose.
Teeth, jaws, bones point to big chill theory
But if anthropoids first appeared in Asia, why didn’t apes and people emerge there, too?
The big chill 34 million years ago is the reason, according to research published in the journal Science.
The left lower jaw of Yunnanadapis folivorus, one of six new fossil primate species found in southern China (Reuters )
This juncture represented “a critical filtering episode during the evolutionary history of primates,” paleontologist Xijun Ni of the Chinese Academy of Sciences’ Institute of Vertebrate Paleontology and Paleoanthropology said.
Before the temperatures dropped, Asia’s primates were dominated by anthropoids.
Afterward, they were dominated by lemur-like primates, with the monkey-like ones decimated. To illustrate that, just one of the six new species unearthed in China’s Yunnan Province was an anthropoid.
Africa was less affected by the plunging temperatures, and its anthropoids became larger and more diverse.
“If early Asian anthropoids had not been able to colonise Africa prior to the [climate] cooling, then we certainly would not be here to ponder such things,” University of Kansas paleontologist Chris Beard said.
“Likewise, if Asian anthropoids had not suffered such big evolutionary losses [after the cooling], our distant ancestors might have evolved in Asia instead of Africa.”
The lone anthropoid in the group — a small, monkey-like primate named Bahinia banyueae — probably resembled some of today’s smaller South American monkeys such as marmosets, Beard said.
Its teeth suggest its diet was mainly fruits and insects.
The six species were represented by fossil teeth, jaws and a few other bones.
Scientists uncover fossils that show why humans did not evolve in Asia 34 million years ago – ABC Online}