Antagonistic Pléiotropie
The antagonistic pléiotropie is a theory relating to the Génétique worked out by the Biologiste George C. Williams in 1957.
Goal
Little time after the discovery of DNA, the scientists tries to explain the ageing from a genetic point of view. Williams thus works out the theory of the antagonistic pléiotropie to find the cause of ageing.
Theory of the accumulation of the changes
The antagonistic pléiotropie is based on the theory of the accumulation of the changes, worked out by the Nobel Prize of medicine Peter Medawar, a British. According to this theory, ageing occurs because of the noxious genetic mutations. However, the effects of these changes appear only after the reproduction, so that the natural selection cannot eliminate the genes, which are transmitted thus from generation to generation, involving ageing, then death, of the people having these genes. There is an accumulation of the noxious changes. This theory is, today, always into force.
The antagonistic pléiotropie
The theory of Williams goes a little further that from Medawar. The American biologist affirms that the genes which cause ageing are not eliminated by the evolution not only because their noxious effects appear after the period of Reproduction, but also because the gerontogenes (genes of ageing) have a beneficial effect before the reproduction.
The gerontogenes are thus pléiotropes: they induce an early benefit and a late harmful effect. For example, the gerontogenes can facilitate an organization to be reproduced and, after the period of reproduction, the same genes can make age the organization.
In other words, according to the theory, to age would be the price to be paid for better aptitudes for the reproduction.
Experimental confirmation
The shrinking of the gene pit 1, in the mouse, involves Nanisme and problems of reproduction, even sterility. However, the lifespan of the mouse is lengthened. The gerontogene pit 1 is thus pléiotrope.
Several tests carried out on other animals made it possible to lengthen their life expectancy, while decreasing some their faculties of reproduction.
Possibilities for the future
Would the withdrawal of gerontogenes at the human one make it possible to lengthen its life expectancy? Several, like the transhumanists, believe in the genetic Engineering to achieve such exploits. The tests were not made yet, and the scientists would face a moral dilemma: can one voluntarily try to lengthen an human life by knowing that the person could not be ready to reproduce correctly?
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