Humans Nearly Went Extinct 1.2M Years Ago 356
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."
There's a message in this somewhere (Score:4, Interesting)
Re:This means ... (Score:1, Interesting)
Re:The new dogma of genetics (Score:4, Interesting)
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.
Re:This means ... (Score:5, Interesting)
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.
Re:The new dogma of genetics (Score:1, Interesting)
"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."
Yet, as we're discovering, "junk" DNA is really a misnomer. Every year, we discover more and more ways in which the supposedly inactive junk DNA actually perform important biological functions. It could also be that selection pressures for a given piece of DNA existed during certain time periods and not others; there is no reason to assume a uniform selection pressure (or lack of pressure) over time. The models in use today assume Hardy-Weinberg equilibrium, which is never observed in the real world, but is somehow assumed to work over millions of years. The theories are non-testable, non-reproducible, and non-falsifiable. In short, it makes dogmatic assertions no better than religious texts.
Re:Summary is wrong (Score:3, Interesting)
The 18500 people quoted is not the number of people capable of breeding, but the "effective population", an abstract measure of genetic diversity in a species. According to TFA, the effective population of modern humanity is about 10000, and the argument in the article is that this much lower diversity indicates that a lot of genetic material must have been lost in a near-extinction event.
Yes, the idea that the "effective" population of today's human race is only 10,000 is the most disturbing thing in the article. If that's true then the vast majority of us are not contributing anything worth noting to the gene pool. That's not a very nice thought.
Re:Do the same tests on different species (Score:4, Interesting)
I disagree. I think you'd see the same correlations in some species, but not necessarily all.
Let's posit some kind of catastrophic event that puts pressure on early hominids. It does not follow that every species is put under evolutionary pressure, only those that rely on the certain ecological resources to survive. So it doesn't have to be an event like nuclear winter.
Furthermore we might not see these effects in other species because most of the species that survived found the changes brought on by the event favorable to them. The ones that didn't for the most part may not have survived, or may have only survived in certain niches.
Hominids are a special case. Except in a few circumstances migration is not part of their lifestyle, but they have a tremendous latent capacity to migrate, probably greater and certainly more flexible than any land animal. So our posited "disaster" happens, but it doesn't look like a disaster to most of the species that survived. As for those for whom it was a disaster, many perish and a few manage to hold on in isolated geographic niches. These are almost certain to include hominids, with their adaptability and latent capacity to migrate great distances. Most of the hominids either don't get moving quickly enough or don't find a place to survive in, but enough of them do to maintain a breeding population.
Of course, this scenario isn't a scientific one. It's more of a counterscenario demonstrating that we wouldn't necessarily expect to see the same genetic phenomena everywhere we looked.
Re:say that to the tasmanian wolf (Score:1, Interesting)
Social security and the welfare state are taking care of that pretty well though.
Re:Toba volcano ? Nuclear winter ? (Score:4, Interesting)
The flood story is most likely a composite of semi-historical and mythological events surrounding the flooding of the Tigris and Euphrates rivers. It may also be related to the flooding of the Persian Gulf at the end of the last glacial period, when trillions of gallons of sea water flooded into what was a very large (and possibly very fertile) valley. Since the destruction caused by this event, and the resulting 10,000 years of salt-water erosion, would've wiped out any sign of an ancient hunter-gatherer or subsistence civilization in what is now the Persian Gulf, it's impossible to prove. But it's still fun to speculate.
alternative: small population left africa (Score:5, Interesting)
Re:say that to the tasmanian wolf (Score:3, Interesting)
Comment removed (Score:3, Interesting)
Re:"Nuclear" Winter (Score:5, Interesting)
Re:This means ... (Score:4, Interesting)
Re:Toba volcano ? Nuclear winter ? (Score:4, Interesting)
Humans Nearly Went Extinct 1.2M Years Ago (Score:5, Interesting)
Bah, you call that news? Try:
"Humans Nearly Went Extinct 27 Years Ago" [google.com]
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. [psychsound.com]
Re:So... BSG was right. (Score:3, Interesting)
When Glen Larson made of the story of BSG, he changed "Noah" to "Adama" to make it seem fictional.
a super-volcano could save earth? (Score:1, Interesting)
After reading this one, I've read about super-volcanoes on wikipiedia, and it says those eruption lower earth's temperature and can trigger a small ice age.
Maybe an eruption like that could save us from global warming?
It's a little bit scary anyway...
Re:Pfft... (Score:3, Interesting)
Written evidence as well as word-of-mouth evidence across many cultures would point towards a fairly recent beginning to civilization. Current scientific methods point towards something older. The situation calls for a reevaluation of the reliability of both methods of evaluation - is historical evidence testable? No. Is scientific evidence subject to human error? Yes. Should we throw out either because one seems to contradict the other? Not necessarily (though we should certainly look towards re-evaluating the bases for our positions). If God created the world in the past 10,000 years, then we should be actively seeking to demonstrate this as fitting with the collected data or not. What we have instead is two completely distinct groups each operating on different originating assumptions. One developed out of 19th century "scientific" assumptions, the other out of particular approaches to reading the text of the Bible / other religious works. Organizations existed in the past to bridge the gap between these two approaches (though they are fewer today).
Re:Pfft... (Score:2, Interesting)
We also have written evidence that Frodo set forth from the Shire in order to destroy the One Ring before it fell into the hands of Sauron. But so what?
Which is more plausible, even as a fictional work, to reality than some of the fanciful imaginations of staunch evolutionists that have been passed on as "scientific" theory and pushed in the academic community as absolute fact (and laugh anybody who disagrees with them out of the journals).
Re:So... (Score:2, Interesting)
More importantly, gene patents existed back then. Most humans were forbidden to express some of their important genes due to patent issues.