Quote:
Originally Posted by Branaddar
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But in all seriousness, we are definitely weakening ourselves as a species. Fertility treatments, cures for genetic diseases, etc all weaken our gene pool by allowing bad genes to propogate. I know that sounds sociopathic of me, and I mean no disrespect to people that have had to deal with these conditions.
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It is clear to me from reading this statement that you do not understand much about genetics. Treatments such as the ones you have listed all proliferate genetic diversity. There is not a geneticist alive in the world that would tell you that genetic diversity is a bad thing.
In the natural order of things, times where a species can proliferate easily allow increased genetic diversity. Human beings have had an unprecedented period of proliferation compared to most recent species. This is a good thing for our future survival.
The benefits of increased genetic diversity come when some sort of event causes the proliferation to end, and a bottleneck begins. A species with a high degree of genetic variance is better equipped to survive when only certain phenotypes are selected for. Famine or disease, for instance, could eliminate a huge portion of a species. If there's some sort of phenotype that allows a certain portion of this species to survive this period of famine or disease, having it equally represented across all genetic profiles (e.g. in a species with a high degree of genetic diversity) will increase the species' chances of survival during and after the genetic bottleneck occurs.
Even if a species survives a genetic bottleneck, it will be less equipped to deal with future bottlenecks because its genetic diversity is decreased. Take, for instance, our bodies' inability to create its own source of vitamin C. The vast majority of mammals have the ability to generate their own vitamin C without requiring external dietary sources. At some point, a genetic bottleneck eliminated that ability in our ancestors, and most hominds lack the ability to produce their own vitamin C. This has not manifested itself as a problem for primates because the diet of many primates is rich with vitamin C. However, this defect (which all humans contain - there is no human alive who can generate his own vitamin C) has manifested itself as a problem in many societies, particularly poorer societies with inadequate nutrition.
The genetic diversity that existed in primates before the bottleneck occured allowed them to survive, even if they survived with this phenotypic defect. This allowed the human species to come to fruition. Proliferation of diverse alelles, whether or not we ascribe to them malignant phenotypes, allowed the human race to exist.