Quote:
Originally Posted by DrKvothe
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The fitness (measured by the relative ability to produce offspring who in turn are capable of reproduction) of an individual human being in the US is largely independent of gene function, as long as certain minimal threshold activities are reach. You can run really fast? Good for you, but tubby McLardFat over there can probably match you on grandchildren (even if we won't live to actually meet them).
Imagine a world where Darwinian selection on us is strong. If you're not optimally athletic or clever, or you're the wrong size or shape or color, you die. Under these conditions, we would all end up pretty damn similar, since certain phenotypes (and the small number of corresponding genotypes) would be necessary for survival.
Genetic polymorphism is a predictable consequence of relaxing Darwinian selection. We're still left with a basic set of purifying selections: if your DNA polymerase has a destabilizing mutation, you're fucked at the cellular level. However, even these are significantly relaxed. I'll elaborate. Fitness benefits for the fastest runner is an example of Darwinian selection. Fitness penalties for those who can't walk but no noticeable fitness benefit beyond a minimum walking speed is an example of a purifying selection. We live in an age of wheelchairs.
It's important to note that this genetic polymorphism is ESSENTIAL to surviving future, unpredictable Darwinian selections. Maybe cyborgs will rise up and kill anyone not in a wheelchair. It's been empirically demonstrated that neutral drift (that is, genetic polymorphism that results from relaxed Darwinian selection) increases the frequency of adaptive mutations within a population compared to constant Darwinian selection.
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In all likelihood some catastrophic disaster will probably result in a global food shortage in the not to distant future leaving many athletic/fit individuals with high metabolisms at a disadvantage, and the ones with an extra 300 pounds of energy reserves and the metabolic ability to make better use of their caloric intake at an advantage.
What's interesting is how some healthcare companies think. Assuming no reproductive intervention, a company that provides a treatment that allows an individual to reproduce (when they otherwise would have died, removing their genome from the subsequent generation) can look forward to more individuals that will need to use their product in the subsequent generation. This is why it is rare to see a for profit organization spending research dollars on cures rather than treatments. Treatments are long-term cash cows.
But how can public dollars/insurance afford to keep treating everyone generation after generation as we further pollute our gene pool?