What Evidence Is There Of A Genetic Bottleneck In Human History?

Human beings are not as genetically diverse as many other species. If you take any two humans, they are much more closely related (share more DNA) than, say, two rats or two dogs. This suggests that at some point in our past the human population whittled down to relatively few individuals who have managed to pass their genes down to us living today.

One effect of this is that humans are more prone to genetic diseases than many other mammals.

Scientists can study mutation rates in genes to trace back female and male lines to a small group of common ancestors about 70,000 years ago. At roughly the same time, a massive volcanic explosion in Indonesia is believed to have altered climate globally, albeit only for a few decades. The resulting hardships on all species are thought to have been particularly tough on humans, who may have been reduced to a as few as 1,000 individuals for a while.

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