Evolution: Monkey see, monkey do (Introduction)

by David Turell @, Saturday, May 07, 2016, 14:40 (2904 days ago)

Fossil finds in China seem to redefine the course of evolution. It appears monkeys were in Asia 40 million years ago and traveled to Africa to complete their evolution to us. Weather change from hot and humid to much colder is also involved:-https://www.washingtonpost.com/news/speaking-of-science/wp/2016/05/06/these-ancient-asian-primate-fossils-might-be-the-missing-pieces-of-a-major-evolutionary-puzzle/?wpmm=1&wpisrc=nl_headlines-"But then, in the 1990s, researchers in China made a surprising discovery: The fossil of a tiny monkey-like creature that was some 10 million years older than anything that had been found in Africa. The ancestors of apes, and ultimately us, seemed to have come from Asia. But they hadn't stayed there.-***-"In a study published Thursday in the journal Science, Beard and his colleagues at the Chinese Academy of Sciences in Beijing report on an “incredible cache” of fossils from 10 previously unknown species uncovered in China's Yunnan province. These fossils help illuminate a new story of our evolution: one in which our primate ancestors evolved in Asia, sailed across a narrow sea to Africa, then were pushed to extinction on their home continent because of drastic climate change. Some of the only primates that survived were the ones whose fossils were just uncovered — primitive creatures that were closer to lemurs than apes and humans living today.-***-"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.-" 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.”-"It was a good thing, too, because climate records show that dramatic changes started ravaging the Earth soon after. Around 34 million years ago, the warm, wet climate of the Eocene gave way to the cooler, drier Oligocene epoch. Tropical forests receded, ... Life for monkeys in Asia suddenly became very, very hard.-***-"Even as Asian anthropoids were dying out in droves, the population of their seafaring African relatives exploded. The species spread and diversified, developing swiftly into the vast variety of primates we know today, from little masked vervets to huge, powerful gorillas to australopithecines such as the famous “Lucy” and, eventually, to us.-***-"Exactly why these primates were so successful is a question for further study, Beard said. It may have been pure chance — evolution rolled the dice in two places, and only one game worked out well. Or it could be that Africa, which was closer to the Equator and less climatically chaotic than Asia, was just a better place to try to survive.-***-"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.”-"They also help pinpoint exactly when “the plot shifted” from Asia to Africa. “Everything that happens subsequently leads to Africa becoming center stage,” Beard said." -Comment: So it isn't just Africa.

Evolution: Monkey see, monkey do stone tools

by David Turell @, Tuesday, September 19, 2017, 17:10 (2404 days ago) @ David Turell

Some monkeys have learned to break open clams by hammering them with stones. So effectively the clam population is growing smaller individuals:

https://www.newscientist.com/article/mg23531441-900-toolwielding-monkeys-push-local-she...

"Long-tailed macaques forage for shellfish on islands off Thailand, then crack them open with stone tools. They target the largest rock oysters, bludgeoning them with stone hammers, and pry open the meatiest snail and crab shells with the flattened edges of their tools.

"These macaques are one of three primates that use stone tools, alongside chimpanzees in Africa and bearded capuchins in South America. “Stone tools open up an opportunity for foods they otherwise wouldn’t even be able to harvest,” says Lydia Luncz at the University of Oxford.

"Luncz wanted to investigate the impact of the monkeys’ shellfish snacking on the prey themselves. Her team followed 18 macaques on their daily foraging routes along the shores of Koram and NomSao, two neighbouring islands off eastern Thailand, recording their tool selection and use. On Koram – the more densely populated island, home to 80 macaques compared with NomSao’s nine – Luncz’s group saw not only smaller oysters and snails, but also fewer of each species. Multiple prey species were less abundant on Koram than NomSao, with four times as many tropical periwinkles on NomSao as on Koram.

“'It’s been shown that systematic predation causes prey of smaller size,” says Nathaniel Dominy at Dartmouth College in Hanover, New Hampshire. The oysters on Koram were about 70 per cent smaller than their counterparts on NomSao, and the periwinkles were less than half the size. A single tool-using monkey on Koram can eat over 40 shellfish a day, so Luncz’s group thinks this predation pressure is driving these shellfish changes.

"Luncz says the macaques might deplete the prey on the islands. Afterwards, they will stop using stone tools and even forget how.

“'Tool use, a socially learned behaviour, has always been viewed as this positive thing that opens up resources,” she says. “But by over-harvesting they’re putting their technology knowledge at risk.”

"What’s more, Dominy thinks the study might help us better understand modern humans’ exit from Africa over 70,000 years ago. One idea is that our ancestors didn’t travel overland, but instead followed the Asian coastline, relying on shellfish for food.

“'Over time, we see a reduction in shell size in the archaeological record, which suggests a systematic use of shellfish,” Dominy says. But nobody was sure whether size reduction was due to changing ocean conditions, or large-scale human predation. “This paper is the first to offer compelling evidence in support of the former,” he says."

Comment: Social learning has been previously demonstrated in monkeys. The use of size reduction in studying human migration is a possible fascinating research approach.

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