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Have Humans Come Close To Extinction?
waytoomuchcoffee writes "According to a new study, our virtually identical DNA indicates humans were close to extinction about 70,000 years ago. Another take on the same study tells how being lactose intolerant in adulthood was normal, and being able to digest lactose became a survival advantage after dairy farming was invented."
Thinking about that, I didn't make myself clear on something. What I was trying to say was that if a single troop of 60 to 70 chimps can have X diversity, shouldn't a group of 60 to 70 humans - a close relative of the chimp - also have X diversity. What struck me about the article is that their implication is that those 2000 people they say sired us had less diversity than 60 to 70 chimps.
Makes you wonder if it has something to do with human females being fertile year round. If I recall, chimp females are not. Because chimps can only mate at certain times, there is less oppurtunity for one male to sire all the children in a troop. In a human harem type social group, this could be easily accomplished which would cut down the genetic diversity considerably. Do this for a couple of generations and you might end up with a population with a depressed gene pool. Anyway, just arm chair theorizing off the top of my head. (Gotta use that anth degree for something.)
Arguably, in spite of our numbers, we're close to extinction now.
Hey, good to know we got out of it last time.
Sunlit World Scheme. Weird and different.
Could the biblical story of Noah's ark explain this, as a worldwide flood leaving only a single family of eight alive will achieve this effect of everyone having similar genes.
Before you mod me down into oblivion for sounding like a self-righteous Creationist, do note that other cultures have references to a catastrophical flood (such as the Chinese, apparently the character for ship is that story).
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I don't expect the BBC to do an exhaustive search of all the peer review journals every time they do a science story, but they should at least check their own archives to help explain an curious conundrum like this one.
The date given for the bottleneck, ~70,000 years ago, coincides perfectly with the largest volcanic explosion in the last half million years. One that spewed thousands of times as much ash as produced in the 1980 Mt. St. Helens eruption.
The explosion of Toba in Indonedia around 74,000 years ago probably caused a greater than 5 degree drop in average global temperature that lasted over 6 years. 5 degrees may not seem like much but that global average may translate to over a 15C drop in the summertime temperatures in the temperate regions and would have devestating effects on many of the plants we relied on for food.
Point is that most of what I just mentioned (and much more) can be found in a few articles on their own web site:
"There is a thin line between ignorance and arrogance, and only I have managed to erase that line." - Dr. Science
I'm surprised that article didn't pick up on the theory that the bottleneck in the genetic line about 70K years ago might well have been due to the eruption of the Toba supervolcano that was regarded as one of the most significant eruptions in the last 2 million years. That kind of climatic change from such an eruption could well be responsible.
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