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."

Comments

BBC should check it's own archives...

[EvilSuggestions]

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:

• Humans came close to extinction (1998)

  A new hypothesis about recent human evolution suggests that we came very close to extinction because of a "volcanic winter" that occurred 71,000 years ago.

  That article discusses a bottleneck of perhaps 15,000 humans. So the only real news is that the estimate of the bottleneck has been cranked back by an order of magnitude.
• BBC Horizon - Supervolcanoes (1999/2000)
• Supervolcanoes could trigger global freeze (2000)
• Walking with Cavemen (2003)