Posted on Monday, August 8th, 2011
Source:The Guardian http://www.guardian.co.uk/science/punctuated-equilibrium/2011/aug/05/2
Punctured Equilibrium, a Guardian Blog talks about Bustard genetics:
Why do we get old and die? Why hasn’t natural selection “weeded out” those genes responsible for age-related declines? Several hypotheses have been proposed, with the most important pointing at the inherent “riskiness” of life. Since most living things don’t survive to old age, deleterious age-related genes or phenotypes may never be expressed and thus, are not available for natural selection to act upon.
Another hypothesis argues that genes or phenotypes that are beneficial early in life can be selected for even though they have negative effects later, effects like senescence. One such hypothesis — which we might think of as the “live fast and die young” hypothesis — blames reproduction for ageing. It proposes that increased reproductive investment actually occurs at the expense of physiological declines in later life (Williams, 1957; free PDF). As any exhausted parent will probably tell you, this hypothesis might actually have merit. Currently, there is little hard data available from long-lived species to adequately test any of these hypotheses.