I thought about going into greater details about the fitness advantage of not synthesizing vitamin C, but decided not to push it since IANAB[iologist].
However, lacking the ability to make vitamin C can also prevent overdoses in vitamin C rich environments. After all, we know that megadoses of vitamin C cause the delusion that vitamin C can cure all kinds of things like colds, flu and cancer. [cf Linus Pauling]
I was reading the ingredients of my dog’s food the other day and it listed vitamin C with an asterisk. The note indicated that vitamin C was not a required nutrient for dogs. I guess some people are concerned that their dogs get enough vitamin C and the dogfood mfg’s go along!
You do realize, don’t you, that the earliest organisms on Earth didn’t use respiration to derive their energy? They use a much simpler, less efficient process called “fermentation.” Respiration as we know it didn’t evolve until both aerotolerance and oxygen-producing photosynthesis had evolved, which took several hundred million years.
Not likely. The gene for creating Vitamin C got turned off (became a “pseudo-gene”) before we diverged from the Chimpanzees. It’s had millions of years to pick up mutations. And mutations accumulate in pseudo-genes a lot faster than they do in expressed genes, because there’s no selection pressure to weed them out.
We’d be better off getting hold of an animal with a working Vitamin C gene and splicing its gene into our genome.
Ulp. Sorry. I was just teasing, but I’ll be more careful in the future. OK, one more time I have to eat my words. So, how’s this instead?
Godsend, I’m extremely disappointed that you never kept your promise to debate. Jesus said not to hide your light under a bushel, and it seems to me that you are hiding under a bushel right about now.
Just a minor nitpick, tracer, but respiration can be both aerobic (with oxygen) and anaerobic (w/o oxygen). Respiration can be defined (see http://www.mblab.gla.ac.uk/~julian/dict2.cgi?5640 ) as “the intracellular oxidation of substrates coupled with production of ATP and oxidized coenzymes (NAD+ and FAD).” Even then, this definition isn’t exhaustive, as other coenzymes can be involved as well. In essence, respiration can be defined as the chemical mechanism for producing energy.
At any rate, I’m pretty sure the original poster meant respiration in an anaerobic sense (e.g., glycolysis, fermentation) and not strictly in an aerobic sense.