Prisoner at War <prisoner_at_war@yahoo.com> wrote:
> the more people you have, the more diversity between individuals
> you'll get, and the more the genetic diversity, the less the chance
> for genetic diseases; thus, genetic diversity should not be a factor
> in genetic diseases because it's precisely the point of genetic
> diversity to resist genetic disease. That's why incest is bad,
> because it doesn't lead to genetic diversity and therefore
> encourages genetic diseases.
In an "established" population, the higher the degrees of inbreeding
and the lower the diversity are, the lower is the proportion of
individuals with genetic diseases. Individuals from inbred populations
have a longer average life span, because deleterious mutations tend to
get eliminated. A recent Italian study highlighted this point and made
it to the newspapers. A much more detailed study that involved dozens
of ethnicities (including lots of Siberian indigenous populations) is
this -
http://www.ncbi.nlm.nih.gov/sites/en...d&uid=10833658
What happens during inbreeding and similarly, in populations of small
size (N) (e.g. during bottlenecks) is that the number of generations
(A) for two alleles with the frequency (p) to end up in the common
ancestor becomes smaller on average.
Surprisingly, this is not an easy problem, with an easy answer, which
is approximately A = 2*p*N. This was found only a couple of years ago
by Nick Patterson
(
http://www.nytimes.com/2006/12/12/sc...pagewanted=all)
through an inventive usage of the diffusion and coalescent theory.
The diversity itself is bound to decrease for a single small
population, but not for a very large population subdivided into a
bunch of small ones that do not interbreed with each other.
Genetic diversity and genetic diseases 
Linear Mode
