What is the minimum number of people needed to create a viable human breeding population?

On Tue, Oct 6, 2009 at 4:27 PM, john jones wrote:
(...)
> Yes but how many different people or uniqe gentic sets are needed to keep the group going with out having to worrie about inbreeding/weak genes taking over?
> This is a different question than what is needed to have a functioning high tech socioty.
(...)

I have seen several answers to that question, ranging from a few
hundred to many thousands of people. Based on historical and evolutive
population bottlenecks known to have occurred along Humanity's
journey, though, I am more inclined to believe in the "few thousands"
figure. For instance, according to the Toba Theory, Humanity may have
dwindled to just 1,000 breeding pairs around 70,000 years.

Bottlenecks far more severe are still possible, though with noticeable
health effects in the population. Those health effects may not be
incapacitating for the society, though. For instance, 40% of all
Ashkenazi jews living nowadays descend from just four women from 2,000
years ago. They do have a higher incidence of A LOT of diseases (some
of them very rare in other groups), but nevertheless in general they
are a long-lived and very productive population.