>10 men in a desert land.. 100 years after.. 10 skeletons..
>
>5 men, 5 women in a desert land.. 100 years after.. A population..
>
>here is what we call the natural..

Your horse fell in the gate Claudio.

If only 10 *men*, yes. It is natural that they would die without offspring.

A more realistic natural setting would be more like this:
10 men on a desert island
-9 are heterosexual, 1 is homosexual
10 women are also on this island (gotta keep it clean somehow)
-7 are heterosexual, 1 is homosexual, 1 is bisexual, 1 is asexual (or acts like it anyway)

Procreation takes place to beat the band as usual - 'naturally' - and soon enough, the natural selection pressures once imposed by the island habitat are circumvented by these clever (and fertile) humans. Some among them recognize this and warn that the island's limited resources and capacity to renew are becoming dangerously outpaced by the procreative impulses of this population. But others among them then respond angrily to this and accuse these 'alarmists' of hating the island, or of not believing in the island Gods, or are simply dismissed as 'whackos'.

Now *that's* natural! ;-)