Whenever I see a film that ends with it being up to a small group of survivors to repopulate the earth, I often find myself thinking that that group seems too small not to cause genetic problems within a few generations – too many cousins marrying each other and whatnot. You catch my drift hopefully.
In: Biology
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70,000 years ago the human population was brought down to 1 to 10 thousand individuals after the Tunguska meteor strike.
Whoops, wrong natural disaster. Comment below corrected me.
Well, to judge by past experience,
> A 2005 study from Rutgers University theorized that the pre-1492 native populations of the Americas are the descendants of only 70 individuals who crossed the land bridge between Asia and North America.[9]
There would have been others, who have no living descendants. And of course, that doesn’t mean they didn’t have inbreeding problems.
> In 2000, a Molecular Biology and Evolution paper suggested a transplanting model or a ‘long bottleneck’ to account for the limited genetic variation, rather than a catastrophic environmental change.[8] This would be consistent with suggestions that in sub-Saharan Africa numbers could have dropped at times as low as 2,000, for perhaps as long as 100,000 years, before numbers began to expand again in the Late Stone Age.[15]
https://en.wikipedia.org/wiki/Population_bottleneck
See also “Minimum viable population”
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Minimum viable population size. Franklin21 has proposed the famous 50/500 rule for minimum effective population size, which has become the threshold to prevent inbreeding depression22. This rule specifies that the genetic effective population size (Ne) should not be less than 50 in a short term and 500 in a long term.Mar 5, 2019
https://www.nature.com/articles/s41598-019-40340-z#:~:text=Minimum%20viable%20population%20size,500%20in%20a%20long%20term.
Less than 50 and its over it would seem.
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