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Thread: Size of Human Population Reduced by Disaster(s)

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    Size of Human Population Reduced by Disaster(s)

    Some time back I read an article about scientists figuring out from studies of DNA that at some point in ancient times, the number of humans on the Earth shrank to about 2,500 individuals due to some calamity. Sadly, I can't find the article now, and my googling efforts have come up empty. Anybody remember seeing the piece and have a link to it?

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    Quote Originally Posted by Tuckerfan View Post
    Some time back I read an article about scientists figuring out from studies of DNA that at some point in ancient times, the number of humans on the Earth shrank to about 2,500 individuals due to some calamity. Sadly, I can't find the article now, and my googling efforts have come up empty. Anybody remember seeing the piece and have a link to it?
    Here's a Wiki article. I have no idea if it is accurate.

    http://en.wikipedia.org/wiki/Toba_catastrophe_theory

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    Our ancestors definitely went through quite a bottleneck, but we can't be sure how small the population became and it may not have been caused by something sudden like the Toba catastrophe. And note that it was only our ancestors who nearly died out. It doesn't mean all big brained hominids were at risk of extinction at the time.

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    Quote Originally Posted by Ronald Brak View Post
    Our ancestors definitely went through quite a bottleneck, but we can't be sure how small the population became and it may not have been caused by something sudden like the Toba catastrophe. And note that it was only our ancestors who nearly died out. It doesn't mean all big brained hominids were at risk of extinction at the time.
    Well, call me a "racist," but I'm not particularly concerned if Neanderthals were thriving at the time.

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    Quote Originally Posted by DrRocket View Post
    Here's a Wiki article. I have no idea if it is accurate.

    http://en.wikipedia.org/wiki/Toba_catastrophe_theory
    That seems to mirror an earlier report I read in the 1980s, though that report didn't mention any particular event, just the fact that the anthropological evidence indicated that around 100,000 years ago it seemed the human race was on the verge of extinction for some reason.

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    Quote Originally Posted by Tuckerfan View Post
    Well, call me a "racist," but I'm not particularly concerned if Neanderthals were thriving at the time.
    Wouldn't that make you a "specist"?


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    If the Toba Event was 70,000 years ago, then the human species had already been in existence for a long time, long enough to spread around most of the globe. If the event was so severe as to reduce the human population to the stated numbers, then the survivors would be distributed in a number of very small groups, totally geographically isolated. Perhaps the groups were small enough to concentrate particular genetic frequencies that characterise the human racial groups. This is a narrative that is at odds with 'out-of africa and subsequent divergence' paradigm, but given the evolutionary timeframe, is perhaps more compelling.

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    Quote Originally Posted by Bearded One View Post
    Wouldn't that make you a "specist"?

    'Sapiensist'


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    Quote Originally Posted by transreality View Post
    If the Toba Event was 70,000 years ago, then the human species had already been in existence for a long time, long enough to spread around most of the globe. If the event was so severe as to reduce the human population to the stated numbers, then the survivors would be distributed in a number of very small groups, totally geographically isolated. Perhaps the groups were small enough to concentrate particular genetic frequencies that characterise the human racial groups. This is a narrative that is at odds with 'out-of africa and subsequent divergence' paradigm, but given the evolutionary timeframe, is perhaps more compelling.
    You seem to be neglecting the possibility that the survivors of the bottleneck were one group who displaced all other h.sapiens lines. Very small groups (a handful of individuals) would be unlikely to survive.

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    Quote Originally Posted by timb View Post
    You seem to be neglecting the possibility that the survivors of the bottleneck were one group who displaced all other h.sapiens lines. Very small groups (a handful of individuals) would be unlikely to survive.
    That makes sense to me and it leads to the question of how the "new world" was colonized by the Paleo Americans where there is no evidence of anything but very small groups that spread geographically rapidly. It may have been unlikely, but survive they did, yet their numbers were still comparatively small when the Europeans arrived (and got smaller thereafter).

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    Do you have any sources for the size of the American founder population? Another possible counterexample is New Zealand, whose pre-European inhabitants were supposedly all descended from 56 women.

    Both cases are special in that the migrants could rapidly multiply because of the very favorable environment. North America and New Zealand both had plentiful game that were unaccustomed to human predation and were therefore "easy". The scenario of post-apocalypse survivors in the Old World may not have been so favorable. More likely the opposite.

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    Quote Originally Posted by timb View Post
    Do you have any sources for the size of the American founder population? Another possible counterexample is New Zealand, whose pre-European inhabitants were supposedly all descended from 56 women.

    Both cases are special in that the migrants could rapidly multiply because of the very favorable environment. North America and New Zealand both had plentiful game that were unaccustomed to human predation and were therefore "easy". The scenario of post-apocalypse survivors in the Old World may not have been so favorable. More likely the opposite.
    My bold

    No, there is nothing but educated guesses. The Archaeologists, the linguists, and the geneticists all have different numbers and timetables. Also, it is conjectured that there were two if not three "waves". Even finding two disparate sites that could be considered contemporaneous is difficult. When they find associated artifacts, the most common is one spear tip in one animal.

    My personal pet guess is that any settlements larger than a few people were drowned when the sea level rose at the end of the last ice age (100 meters at the end of the younger Dryas) on the Pacific coast. (see Dixon et al; many books and papers). We should be seeing something from Adavasio's group shortly, who just completed an expedition a hundred miles off St. Petersburg, Florida with ROV's (Mercyhurst, NOAA) in several hundred feet of water.

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    Quote Originally Posted by jlhredshift View Post
    That makes sense to me and it leads to the question of how the "new world" was colonized by the Paleo Americans where there is no evidence of anything but very small groups that spread geographically rapidly. It may have been unlikely, but survive they did, yet their numbers were still comparatively small when the Europeans arrived (and got smaller thereafter).
    IIRC, the population of the Americas (North, South, Central) is estimated to have been roughly similar to that of the "Old World" but was rapidly decimated when Columbus, and those who followed him, brought Old World diseases that the natives had no immunity to.

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    Quote Originally Posted by Tuckerfan View Post
    IIRC, the population of the Americas (North, South, Central) is estimated to have been roughly similar to that of the "Old World" but was rapidly decimated when Columbus, and those who followed him, brought Old World diseases that the natives had no immunity to.
    I do not think so only because that would have really stood out to me if I had read that. On the other hand, I confine my reading up to the end of the last Ice Age at about 9ka Rcybp and don't pick up again until about the middle 1800's; do to personal interests and lack of time.[I am still looking for that life off with pay gig]

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    In the case of an already spread out humanity, the survivor groups are most likely already going to be located in the most favourable habitats; they don't have to move to and colonise them subsequently, so numerical recovery would be quick, much faster than post-Toba migrations from a single surviving population. In actual fact, looking at the ubuiqity of human artifacts back to 200,000yr world wide from japan to americas, I doubt that Toba was a bottleneck, it must be older, much older.

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    Quote Originally Posted by transreality View Post
    In the case of an already spread out humanity, the survivor groups are most likely already going to be located in the most favourable habitats; they don't have to move to and colonise them subsequently, so numerical recovery would be quick, much faster than post-Toba migrations from a single surviving population. In actual fact, looking at the ubuiqity of human artifacts back to 200,000yr world wide from japan to americas, I doubt that Toba was a bottleneck, it must be older, much older.
    Not in the Americas, the oldest, and highly contested still, is 34kya to 20kya, at Topper, Meadowcroft, and Monte Verde. These pieces are small chunks of charcoal in "fire pits" and even the primary researchers would like to see firmer evidence.

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    Quote Originally Posted by jlhredshift View Post
    Not in the Americas, the oldest, and highly contested still, is 34kya to 20kya, at Topper, Meadowcroft, and Monte Verde. These pieces are small chunks of charcoal in "fire pits" and even the primary researchers would like to see firmer evidence.
    I was reading of the Calico specimens, however, maybe they aren't taken seriously, which would leave a big gap to 48,000 as the oldest from pedra furada, and even then, its sparse...

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    Quote Originally Posted by transreality View Post
    I was reading of the Calico specimens, however, maybe they aren't taken seriously, which would leave a big gap to 48,000 as the oldest from pedra furada, and even then, its sparse...
    It's all sparse. The three best researched sites, Topper, Meadowcroft, and Monte Verde, of an occupation are not where it would be expected for first arrivals; i.e. the Pacific Northwest or Alaska, far from it. The other troubling thing is when we do get good associated sites, its just prior to and during the younger Dryas when there is a RadioCarbon "plateau" and the greatest amount of "calibration" needs to be applied to the samples; which is why the papers always use Rcybp to avoid confusion. (Link to earlier post with Rcybp conversion chart.)

    I have noticed that the Archaeologists, the linguists, and the geneticists never agree on dating, so the 70kya - 100kya bottleneck is suspect to me as well.
    Last edited by jlhredshift; 2009-Aug-28 at 10:17 PM. Reason: added link to Rcybp chart

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    By the way, going to the OP title, the Clovis culture disappeared and then there was the Folsum culture; pre and after the younger Dryas respectively.

    Right in the middle of that carbon excursion; linkage????????

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    Obviously some up-to-speed anthropologists in our midst have gone off on a tangent without mentioning the evidence from mitochondrial DNA which suggests our species is descended from a very small population of females in Africa before we dispersed from that Continent, which would address the original question. The 'calamity' which so reduced the number of individuals is thought to be climate change in East Africa and speculation poses these few individuals must have overcome the environmental challenges they were facing in a radical and novel manner, endowing their descendants with peculiar talents for modifying their environment and adaptation. That's you and me, makes ya proud

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    Quote Originally Posted by Tuckerfan View Post
    Some time back I read an article about scientists figuring out from studies of DNA that at some point in ancient times, the number of humans on the Earth shrank to about 2,500 individuals due to some calamity. Sadly, I can't find the article now, and my googling efforts have come up empty. Anybody remember seeing the piece and have a link to it?
    Check out Spencer Wells and the Genographic project. He has written several papers on the subject. He also gave a wonderful presentation at TED in 2008. He presented the human family tree, and related it to migration and weather.

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    Quote Originally Posted by Middenrat View Post
    evidence from mitochondrial DNA which suggests our species is descended from a very small population of females in Africa before we dispersed from that Continent, which would address the original question.
    yeah, but when? As a matter of course at the speciation event, but has there been a subsequent bottleneck e.g. at the Toba event?

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    A physical disaster should have affected the Neanderthal as well, did it?

    Australia was colonised 40ky to 50kya, approximately, maybe earlier.

    Major glaciation was occurring in the stated time frame; sea levels rise and fall.

    Could we call the genetic bottleneck an extinction like event?

    How about this thought; when did Homo sapiens sapiens discover that it made a difference with who you had children with, i.e. interbreeding? What today we would call a sense of morality, but to those populations they would at some point discover that survivability of offspring is increased when the chosen mate is not part of the family group. This had to happen at some point in our history, when? Is it contemporaneous with the end of the genetic bottleneck? This would not be something that would show itself in the archaeological record.

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    Quote Originally Posted by jlhredshift View Post
    How about this thought; when did Homo sapiens sapiens discover that it made a difference with who you had children with, i.e. interbreeding?
    That's actually somewhat hardwired into us. Women prefer men who smell different than they do. Reason being that the differences in natural odors are indicative of a different immune system, and thus any off-spring would have a greater chance of survivability.

    Cite. Cite 2.

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    Quote Originally Posted by Tuckerfan View Post
    That's actually somewhat hardwired into us. Women prefer men who smell different than they do. Reason being that the differences in natural odors are indicative of a different immune system, and thus any off-spring would have a greater chance of survivability.

    Cite. Cite 2.
    Ok, makes sense that they would smell.

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    Quote Originally Posted by jlhredshift View Post
    My personal pet guess is that any settlements larger than a few people were drowned when the sea level rose at the end of the last ice age.
    I think "drowned" is way too strong of a word, jihredshift, as many people outran the recend Indian ocean tsunami, even though it impacted coastlines over the time span of just a few seconds. By comparison, the rising of seas due to the many previous global warming spells that have hit the Earth, all entirely without any human input, produce sea rises of such a slow nature that it takes generations to overrun human civilization.

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    Unless they were stranded on land that then became submerged.

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    Quote Originally Posted by mugaliens View Post
    I think "drowned" is way too strong of a word, jihredshift, as many people outran the recend Indian ocean tsunami, even though it impacted coastlines over the time span of just a few seconds. By comparison, the rising of seas due to the many previous global warming spells that have hit the Earth, all entirely without any human input, produce sea rises of such a slow nature that it takes generations to overrun human civilization.
    I'm sorry "drowned" in this context is geologic jargon for any river, bay, coastline, estuary that has been submerged under water. It has nothing to do with people.

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    Quote Originally Posted by transreality View Post
    If the Toba Event was 70,000 years ago, then the human species had already been in existence for a long time, long enough to spread around most of the globe. If the event was so severe as to reduce the human population to the stated numbers, then the survivors would be distributed in a number of very small groups, totally geographically isolated. Perhaps the groups were small enough to concentrate particular genetic frequencies that characterise the human racial groups. This is a narrative that is at odds with 'out-of africa and subsequent divergence' paradigm, but given the evolutionary timeframe, is perhaps more compelling.
    That isnít whatís being suggested by the genetic data. Humans as a species have a remarkably small amount of generic variation, smaller then almost any other large mammal.

    The most likely explanation for this would be the near extinction of homo sapiens, followed by a rapid growth of a small isolated population to fill the gaps this left. Multiple populations centers donít explain the small amount of genetic variation we humans currently have.

    Also, it's worth noting that humans have a relatively long development time. I.E. 50K - 70K years is only about 2500-3000 generations.

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    Nonetheless races exist, and provide evidence for some regional genetic variation and isolation in the past. The genetic variation of the species is something that is determined at the speciation event, by the genetic variation of the first ancestor and the subseqent rate of evolution of her family (the time to fix the genes). The racial variation proably has not existed for the 600kyr history of the species, but is something that may have arisen in a more recent (eg, Toba) event. In this the individual proto-races may have small variation to the main pool, but the effect of on-going recombination is to recover the original variation of the species. The alternative is the races diverge sequentially from the migrating core group, but is there any evidence for that?

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