| Space | SETI | Where Are The Aliens? (1) (2) | Climate | UFOs | |||||||||||||||
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Here are two related articles from the BBC Science site. According to the first article: |
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The volcano Toba, in Sumatra, is believed to have experienced a severe eruption 71,000 years ago. The result was a "volcanic winter" (similar to a "nuclear winter" or "asteroid winter") that lasted six years. During those years, the ash spewed by the volcano circled the globe, blocked the sun, and caused global temperatures to fall. The climate was significantly changed for another 1,000 years. During the first six years (and perhaps for many of the next 1,000) drought and famine resulted. It's believed that no more than 15,000 people survived. |
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Note that the story doesn't say "15,000 people in Indonesia" or "15,000 people in a region of Asia near the eruption." It says "15,000 people." If this story is accurate, this means the entire human race (after the eruption) was composed of 15,000 people. Had something happened to them, we wouldn't be here.
The other piece of the puzzle comes from the second article: |
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Unlike in chimpanzees (human's closest genetic relatives), there is relatively little variation in human DNA. It is possible to find more genetic diversity in a single group of chimps than in all six billion humans alive today. Humans and chimpanzees are thought to have split from a common ancestor five to six million years ago, which is more than enough time for humans to develop substantial genetic differences. The lack of differences causes some researchers to believe that something in the recent past (within 100,000 years or so), caused the human population to shrink dramatically. This would have dramatically reduced the genetic variation within the human race. |
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The second article seems to confirm the first. Also, while the first mentions 15,000 humans, the second says that humanity may have been reduced to only about 2,000 people.
The significance of these articles to the search for extraterrestrial intelligence should be clear. According to the articles, the human race came very close to extinction. If other intelligent races, elsewhere in the galaxy, were just a bit less lucky than we were, they would have disappeared. If the kind of near-extinction experience we survived is common to intelligent races, most of them may have died out before they could develop technological civilization. (In other words, the value of fT in the Drake equation would be near zero.) The source that pointed out the connection to both these stories was Jay Manifold. |
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