Thursday, 26 September 2019

How many people are required to maintain genetic diversity?


Imagine humans were to colonize a distant planet and it was a single one-way trip. How many people would they need to bring?


Obviously 2 is the minimum, but that would result in a lot of inbreeding.


So what number is the minimum number of people you can have in an isolated community and still maintain a healthy diversity?



Answer



Actually it is a very important question for laboratory animals (and, I imagine, endangered species) and was calculated to be 25 couples.



With any number of animals (including humans), there is always some inbreeding happening, but you can reduce it with the number of breeding pairs and careful pairing. When you get to 25 pairs (50 animals) and have complete control over pairing, you can sustain the genetic diversity practically infinitely (especially if you take into account spontaneous mutations).


Of course, such control over who can have children with who (plus whether one is at all allowed to procreate and what will be the sex of their children!) would be questionable morally, so in case of populating a distant planet, we would need a larger group, to provide for sexual preferences, fertility problems etc.


Some information on laboratory outbred stocks.


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