Of all the creatures you could call evolutionary icons — peppered moth, Darwin’s finches, Haeckel’s embryos — arguably the most risible is the rafting monkey. Even Darwinists seem to understand this.

A Washington Post article includes an interview with an author of a new Science paper, “Oligocene primates from China reveal divergence between African and Asian primate evolution,” that once again renews the demand for belief in seafaring monkeys. We’ve covered this paradox before — monkeys can’t swim much less sail. Just last month evolutionary theorizing dodged a bullet by avoiding the spectacle of rafting foxes on the world’s oceans.

The researcher, Christopher Beard, explained to reporter Sarah Kaplan how it must be the case that tarsier-like monkeys, evidenced by fossil teeth found in China, sailed on clumps of earth and felled trees, 30-40 million years ago, across an aquatic void separating Asia from Africa, which was then an island:

“It’s a little complicated,” Beard said, almost sheepishly.

You don’t say.

This more convoluted version of our history begins in the Eocene, some 40 million years ago. At this time, Earth’s climate was hot and humid, and the continents were just beginning to move into the positions they hold today. India was zooming headlong toward the bottom of Asia (the inevitable collision would one day give rise to the Himalayas). An inland sea flooded the center of the Eurasian land mass. And Africa was an island continent, separated from Asia and Europe by a narrow stretch of ocean.

Early anthropoid (humanlike) monkeys were flourishing in Asia at that time. But they also, somehow, found a way to migrate across the watery barrier to Africa. And since monkeys don’t really swim, scientists’ best theory about their migration is — I kid you not — that they sailed across on rafts made of trees.

“You’re laughing,” Beard said, “but it’s now known that this happened repeatedly. Because of the greenhouse conditions, a lot of monsoons were hitting Asia at the time. When that happens, rivers would flood, riverbanks erode. A half an acre of land with a bunch of trees growing out of it falls into a river and floats out to sea.”

“And if there are a bunch of monkeys hanging out in the trees when that happens,” he continued, “suddenly those monkeys become sailors.”

“I kid you not.” “You’re laughing, but it’s now known that this happened repeatedly.” It is “known” not because anyone can picture the scenario without cracking up or feeling “sheepish” but because the theory demands it. See here for Casey Luskin’s earlier comments on the “biogeographical conundrum” posed by these Chinese monkeys.

And look here for pictures of how the drifting continents were disposed in the relevant time period between the Oligocene and the Eocene. From Asia to Africa by sea was a considerable distance, and monkeys are supposed to have accomplished this feat while clinging for dear life to bits of earth and tree debris? On Lake Washington near our home, I beg my wife and kids not to row out even close to shore on a store-bought inflatable raft!

Science Daily has additional thoughts from Dr. Beard on the “‘mother lode’ of a half-dozen fossil primate species.” A half-dozen is a “mother lode”? More:

These primates eked out an existence just after the Eocene-Oligocene transition, some 34 million years ago. It was a time when drastic cooling made much of Asia inhospitable to primates, slashing their populations and rendering discoveries of such fossils especially rare.

“At the Eocene-Oligocene boundary, because of the rearrangement of Earth’s major tectonic plates, you had a rapid drop in temperature and humidity,” said K. Christopher Beard, senior curator at the University of Kansas’ Biodiversity Institute and co-author of the report. “Primates like it warm and wet, so they faced hard times around the world — to the extent that they went extinct in North America and Europe. Of course, primates somehow survived in Africa and Southern Asia, because we’re still around to talk about it.” Because anthropoid primates — the forerunners of living monkeys, apes and humans — first appeared in Asia, understanding their fate on that continent is key to grasping the arc of early primate and human evolution.

Sarah Kaplan’s article in the Post speaks more than once of the fossils as “fill[ing] in the gaps”:

The fossils “fill a gap,” in our understanding of our evolutionary history, Stony Brook University primatologist John Fleagle, who was not involved in the study, told the Christian Science Monitor. They illustrate “a whole aspect of primate evolution that wasn’t clearly documented before.”

But the value of “filling a gap” lies in reducing the distance you have to leap in order to believe something seemingly far-fetched. More about rafting animals surely makes the challenge for evolution tougher, not easier. I would have said reducing, not increasing, the number of such unlikely sailors would “fill a gap.”

Image credit: IVPP, Chinese Academy of Sciences; University of Kansas; via Science Daily.