Population bottleneck
In evolution theory, a population bottleneck (or genetic bottleneck) is an evolutionary event in which a significant percentage of a population or species is killed or otherwise prevented from reproducing, and the population is reduced by 50% or more, often by several orders of magnitude. A graph of this change resembles the neck of a bottle, from wide to narrow; hence the name.
In evolutionary theory, population bottlenecks are thought to accelerate the processes of natural selection and genetic drift.
Humans today are a legacy of a population bottleneck which occurred 70,000 years ago. This has had the result of limiting the overall level of genetic diversity in the human species, possibly by a large amount.
See also
population genetics - small population size - founder's effect - overpopulation - ice age - Black Death - AIDS - Toba catastrophe theory
