EvC Forum: Nested Biological Hierarchies

nemesis_juggernaut writes:

That's a perfectly good question, but I can't help but noticing the level incredulity ascribed to it. By the same premise I could just as easily ask why natural selection did not choose to keep such a gene,

(My bold.) A nitpick - be careful of anthropomorphic (theomorphic?) phrasing in reference to natural selection.

nemesis_juggernaut writes:

when I think we could all agree that possessing the ability to synthesize our own vitamin C would be most beneficial. So what happened that we should lose the ability when its more than evident that vitamin C plays a significant role in our health? It would be one thing to lose a function simply because we don't need it anymore, such as the appendix, as some would suggest and yet still retain some atavistic traits reminiscent of a once fully functional gene. But this isn't the case because vitamin C is necessary in our diet.

Not at all. If an organism's diet is saturated with vitamin C, then the ability to synthesize it becomes a neutral trait. Perhaps even slightly negative, if there is significant metabolic cost involved. Obviously, with our current lifestyle it would be beneficial to be able to manufacture our own. However, the ability was apparently lost before our lineage diverged from that of chimps, which bear the same genetic defect. Obviously, chimps are able to live on the high levels of ascorbic acid in their native diet, just as guinea pigs and many other animals are. As were our hunter-gatherer ancestors, for the most part. It's an abundant nutrient for those not living primarily on the meats and grains of an agricultural society.

Edit: Apparently I was much too slow, and Coragyps beat me to the Submit button by quite a margin.

Edited by Belfry, : No reason given.

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