Millions of generations old: Once lost, diversity of gene pools cannot be restored

Abstract

The present diversity of species is the result of a very long and slow process of genetic change and adaptation. The time necessary for the emergence of new species, and even for the accumulation of genetic variants at individual gene loci within species, greatly exceeds the time since the emergence of Homo sapiens. New techniques of molecular biology combined with recent theories in population genetics allow us to assess the time dimension of genetic change; these suggest that some genetic polymorphisms may have originated over a million generations ago. In other words, once lost, any particular genetic adaptation cannot be regained in any realistic time interval. We depend on biological systems for food, fiber, energy and medicinal needs. Continued advances in each of these areas may be compromised by losses of the