[ExI] homo sapiens as endangered species
anders at aleph.se
Thu Jun 2 19:33:53 UTC 2011
Stefano Vaj wrote:
> On 2 June 2011 18:58, Anders Sandberg <anders at aleph.se
> <mailto:anders at aleph.se>> wrote:
> When I saw the subject of this thread I thought it was more about
> xrisks. I have been tinkering with some minimum viable population
> models of H. sapiens. If we are ever near extinction, it is pretty
> tough to maintain a population - big mammals are tricky.
> I have some vague recollection of this notion, but do not remember the
> reasoning behind it.
> Why a few fertile individuals are actually not enough?
Low genetic diversity is less of an issue than many think (but it
contributes a bit). The real threat is demographic noise: a small
population will have larger relative fluctuations, some of which can
drive it down to even smaller and even more vulnerable. A species
"circling the drain" can run into problems both with bad years, with few
children due to bad luck, bad luck with gender ratios, Allee effects and
a bunch of other things.
In my sims I need about 2000 people to get long term survival with more
than 90% probability. Smaller populations can survive, but they need to
Future of Humanity Institute
Philosophy Faculty of Oxford University
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