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Humans Nearly Went Extinct 1.2M Years Ago
Hugh Pickens writes "Scientific American has a story on researchers from the University of Utah who have calculated that 1.2 million years ago, at a time when our ancestors Homo erectus, H. ergaster, and archaic H. sapiens were spreading through Africa, Europe, and Asia, there were probably only about 18,500 individuals capable of breeding in all these species together (PNAS paper here). Pre-humans were an endangered species with a smaller population than today's gorillas and chimpanzees. Researchers scanned two completely sequenced modern human genomes for a type of mobile element called Alu sequences, then compared the nucleotides in these old regions with the overall diversity in the two genomes to estimate differences in effective population size, and thus genetic diversity between modern and early humans. Human geneticist Lynn Jorde says that the diminished genetic diversity one million years ago suggests human ancestors experienced a catastrophic event at that time as devastating as the Toba super-volcano in Indonesia that triggered a nuclear winter and is thought to have nearly annihilated humans 70,000 years ago."
I think this means we are a stubborn infestation, successfully resisting the Universe's attempts to exterminate us thus far. The Universe realized that we are harder to kill than cockroaches, and concluded that the only way to wipe us out is to place the means of our destruction in our own hands. Now, it's just a waiting game.
I prefer rogues to imbeciles because they sometimes take a rest.
The DNA that creates different physical traits does mutate in (more or less) unpredictable leaps and bounds as time goes on. But that's not the DNA they look at in cases like this. There's long strings of junk DNA that does nothing at all - random leftover of mutations that didn't happen to affect our survival one way or the other. Because these don't affect physical traits, they aren't selected for or against and are subject to only one 'force', genetic drift. That's why they're fairly constant.
More than that, I read a year or so ago (it may have been covered at slashdot, I don't remember) that it was mathematically proven that everyone on earth shares common anscestors from as little as a thousand years ago.
Besides, there was the other near extinction 70K years ago. Wht I find interesting is the near extinctions were probably what led to modern humans' intelligence and other traits (like humor) that makes us so different from other species.
Free Martian Whores!
The TWO (only two) genomes analyzed were from the subpopulation which left Africa. If you fully sequence a native south African more genomic variety, this hypothesis may not hold up.
But, the effect was spread on all H. Sapiens level species more or less equally, giving the more adaptable group the advantage of a sparse landscape. If the near-extinction event hadn't happened, H. Sapiens would likely have been out competed by entrenched specialists.
Bah, you call that news? Try:
"Humans Nearly Went Extinct 27 Years Ago"
the commander's Wikipedia entry says he:
You can follow any of the links in the above search, or here's a particularly lively read.