On Friday, September 1, 2023 at 8:21:00 AM UTC-4, ltlee1 wrote:
"Human ancestors in Africa were pushed to the brink of extinction around 900,000 years ago, a study shows. The work1, published in Science, suggests a drastic reduction in the population of our ancestors well before our species, Homo sapiens, emerged.
The population of breeding individuals was reduced to just 1,280 and didn’t expand again for another 117,000 years.
“About 98.7% of human ancestors were lost,” says Haipeng Li, a population geneticist at the University of Chinese Academy of Sciences in Beijing, who co-led the study. He says that the fossil record in Africa and Eurasia between 950,000 and 650,000
years ago is patchy and that “the discovery of this bottleneck may explain the chronological gap”.
Nick Ashton, an archaeologist at the British Museum in London, who wrote a related perspective2, says he was intrigued by the tiny size of the population. “This would imply that it occupied a very localized area with good social cohesion for it to
survive,” he says. “Of greater surprise is the estimated length of time that this small group survived. If this is correct, then one imagines that it would require a stable environment with sufficient resources and few stresses to the system.”"
https://www.nature.com/articles/d41586-023-02712-4
A side of story of novel statistical methods:
"If the research holds up, it will have provocative implications. It raises the possibility that a climate-driven bottleneck helped
split early humans into two evolutionary lineages — one that eventually gave rise to Neanderthals, the other to modern humans.
But outside experts said they were skeptical of the novel statistical methods that the researchers used for the study. “It is a bit
like inferring the size of a stone that falls into the middle of the large lake from only the ripples that arrive at the shore some
minutes later,” said Stephan Schiffels, a population geneticist at Max Planck Institute for Evolutionary Anthropology in Leipzig,
Germany.
...
Haipeng Li, an evolutionary genomics researcher at Chinese Academy of Sciences in Shanghai, and his colleagues spent over
a decade creating their own method for reconstructing evolution.
The researchers named the method FitCoal (short for Fast Infinitesimal Time Coalescent). FitCoal lets scientists cut up history
into fine slices of time, allowing them to create a model of a million years of evolution divided into periods of months.
“It is a tool we created to figure out the history of different groups of living things, from humans to plants,” Dr. Li said.
At first he and his colleagues focused on animals like fruit flies. But once enough genetic data from our own species had been
sequenced, they turned to the history of humans, comparing the genomes of 3,154 people from 50 populations around the world.
The researchers explored various models in order to find one that best explains today’s genetic diversity among humans. They
ended up with a scenario that included a near-extinction event among our ancestors 930,000 years ago.
“We realized we had discovered something big about human history,” said Wangjie Hu, a computational biologist at the Icahn
School of Medicine at Mount Sinai in New York and an author of the study."
https://www.nytimes.com/2023/08/31/science/human-survival-bottleneck.html
But I am still surprised by the the "population of breeding individuals was reduced to just 1,280."
Just 1280. Not a range.
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)