Posted on 01/19/2010 4:21:03 AM PST by Pharmboy
From the composition of just two human genomes, geneticists have computed the size of the human population 1.2 million years ago from which everyone in the world is descended.
They put the number at 18,500 people, but this refers only to breeding individuals, the “effective” population. The actual population would have been about three times as large, or 55,500.
Comparable estimates for other primates then are 21,000 for chimpanzees and 25,000 for gorillas. In biological terms, it seems, humans were not a very successful species, and the strategy of investing in larger brains than those of their fellow apes had not yet produced any big payoff. Human population numbers did not reach high levels until after the advent of agriculture.
Geneticists have long known that the ancestors of modern humans numbered as few as 10,000 at some time in the last 100,000 years. The critically low number suggested that some catastrophe, like disease or climate change induced by a volcano, had brought humans close to the brink of extinction.
(Excerpt) Read more at nytimes.com ...
Yes, I know that, but it is just the way that the catch-phrase "Climate Change" is bandied about - I think the author was making a veiled reference to "the defining issue of our age" because they just cannot help themselves
HA!! I wrote the same thing above...
"The strategy"? "Investing"?
Well, which is it? Is variation directed or is it undirected, or is the above just another 'unfortunate' and inconsistent lapse into teleological double-talk? Call me a monkey's uncle, but If new variation arising from recombination and mutation is accidental and adaptively random in direction then I should like to know exactly what the genetic mechanism is that has the foresight to strategically direct mutations to invest in novel adaptive requirements.
Cordially,
1) Our hands are very similar to other primate hands and are formed that way for grasping tree limbs. When we hit the ground running (so to speak) those same hands were now great for manipulating the environment and making tools and wielding weapons.
2) We humans have a genetically-endowed ability to deal with ambient radiation. At tis point, it does not matter; but if and when ambient radiation increases to where it might kill 20% of the most vulnerable population, it comes into play though the variation was silent before the increase.
"Ineffective Population" PING
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I missed that “defining issue of our age” crack. For sure, that sounds like someone hooked on the AGW Kool-Aid.
This bottleneck was likely the mount Toba eruption about 85000 years ago. We almost went extinct. The local isolated populations that survived and expanded likely became the different races, the reason why such distinct characteristics arose despite such a small and genetically uniform population.
Global warming from the end of the last age is what allowed a larger population. We need it to stay warm unless we want to risk a declining population with everyone fighting over non-freezing territory.
More free time, the ability to stay in one place, the ability to live through an injury that might have otherwise doomed you had you needed to migrate, etc...
...and more food!
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Thanks Pharmboy.it seems, humans were not a very successful speciesWow, it's amazing how foolish gradualist biases make people appear (the author, not you, obviously! :'). Oh nuts, this is a two-list topic, prefer to do Catastrophism first in such cases, oh well... |
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We only became a successful species when we elected BHO to the presidency...
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Sticking to science, the generally quoted figure for that megavolcano Toba is about 74,000 years ago, not 85 thousand. What gets me is the lack of significant communication between different science disciplines. This post vaguely suggests a genetic bottleneck perhaps cause by climate change and a volcano. This is already pretty well established science. Toba is a caldera 18 by 65 miles in size. Pinatubo left a caldera 1 1/2 to 3 miles in diameter. Most of us remember the 500 year floods of the Mississippi, and other severa weather for several years after.
I have several questions. How big was the population immediately before Toba? Could the Toba bottleneck have affected the genetics of this study so that their figure for the humanoid population a million years ago might be seriously underestimated? There is no doubt that there was a significant downward movement of temperature in the millenia after Toba, and from everything I read in archaeology/anthropology, it was not until about 50 thousand years ago that enough population had regenerated to start leaving significant traces/finds.
Also from about 30 to 20 thousand years ago, there were several additional sharp drops in temperature, until the climate began to warm about 18,000 years ago. I have identified one drop at 22,000 ya when Sakura-Jima volcano blew leaving a 15 mile diameter caldera. Anyone have candidates for at least two other significant drops between 20 and 30 thousand years ago?
I’m not sure if anyone has ever been able to do a proper estimate, but it is easy for me to think that the world-wide population could have been much larger than most people might imagine.
Moreover, the “bottleneck” population estimates are made on the basis of a genomic analysis and hence only estimates the size of the population that contributed to the majority modern human genome.
There is, I think good reason to believe that some fairly significant populations of pre-Toba humans could have survived to the east of the Toba caldera, in Java, the lesser Sunda Islands, and what is now New Guinea, as well as in some parts of penninsular Malaysia.
These stocks may be the ancestors of the negroid peoples of New Guinea and the Andaman Islands. These groups have not made any significant contribution to the wider gene pool, and would have been immaterial to the bottleneck. They may have survived in much larger numbers than the majority ancestors, only to dwindle later under pressure from modern humans in the last 15-20 thousand years.
Perhaps some hominid variants such as the “hobbit” people of Sumba who apparently co-existed with pygmie elephants right up to the arrival of modern humans a few thousand years ago were survivors of the Toba event.
For the first time in my life, I was proud to call myself human.
I think the article said they did their extrapolations from only 2 genomes. I am sure there are a number of genomes of isolated populations that could indicate a much larger population—the Saami of Finland, the Basques, the bushmen and pygmies, Esquimos, New Guinians, etc. Also, the south east Asian areas, especially islands would have been much larger, given that the water level was several hundred feet lower than today.
Regarding the Hobbits, I recently read an article saying that they were 700,000 years old. Of course in the past 100,000 years until they died out, their island would have been much larger because of sea level.
I recently read an article in Archeology Magazine about finding remains in India that dated to right after Toba. I might be able to locate it and add some information if you are interested.
Shockingly heteronormative.
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