Here’s a scary environmental news story, via AFP, that says the human population decreased to 2,000 people 70,000 years ago due to “extremes of climate” (the AP has a less misleading and more interesting story on the same subject):

Human beings for 100,000 years lived in tiny, separate groups, facing harsh conditions that brought them to the brink of extinction, before they reunited and populated the world, genetic researchers have said. “Who would have thought that as recently as 70,000 years ago, extremes of climate had reduced our population to such small numbers that we were on the very edge of extinction,” said paleontologist Meave Leakey, of Stony Brook University, New York. The genetic study examined for the first time the evolution of our species from its origins with “mitochondrial Eve,” a female hominid who lived some 200,000 years ago, to the point of near extinction 70,000 years ago, when the human population dwindled to as little as 2,000.

Here’s the entire article (pdf) and an abstract of the article that appeared in The American Journal of Human Genetics:

The Dawn of Human Matrilineal Diversity — The quest to explain demographic history during the early part of human evolution has been limited because of the scarce paleoanthropological record from the Middle Stone Age. To shed light on the structure of the mitochondrial DNA (mtDNA) phylogeny at the dawn of Homo sapiens, we constructed a matrilineal tree composed of 624 complete mtDNA genomes from sub-Saharan Hg L lineages. We paid particular attention to the Khoi and San (Khoisan) people of South Africa because they are considered to be a unique relic of hunter-gatherer lifestyle and to carry paternal and maternal lineages belonging to the deepest clades known among modern humans. Both the tree phylogeny and coalescence calculations suggest that Khoisan matrilineal ancestry diverged from the rest of the human mtDNA pool 90,000-150,000 years before present (ybp) and that at least five additional, currently extant maternal lineages existed during this period in parallel. Furthermore, we estimate that a minimum of 40 other evolutionarily successful lineages flourished in sub-Saharan Africa during the period of modern human dispersal out of Africa approximately 60,000-70,000 ybp. Only much later, at the beginning of the Late Stone Age, about 40,000 ybp, did introgression of additional lineages occur into the Khoisan mtDNA pool. This process was further accelerated during the recent Bantu expansions. Our results suggest that the early settlement of humans in Africa was already matrilineally structured and involved small, separately evolving isolated populations.

The study itself says: “The quest to explain demographic history during the early part of human evolution has been limited because of the scarce paleoanthropological record from the Middle Stone Age.” That is of course true, and overly precise estimates of human population in ancient days would be suspect. But the study itself makes no such claims. The scholarly article never says that there were 2,000 humans 70,000 years ago. Moreover, variations of the word “environment” appear only twice, and there is no discussion whatsoever of “extremes of climate.”

This entry was posted on Friday, April 25th, 2008 at 7:48 pm and is filed under General, MSM, Science. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.