On Wed, 5 Apr 2000 00:10:24 -0700, alexs <[log in to unmask]> wrote:
I wrote:
>>Dependency on vitamin C (as only primates and very view animals show)
>>could have evolved, in my opinion, only in an environment where the
>>regularly vitamin C supply was so constant and high than body's
>>synthetisation wasn't used for *very many* generations.
>
alexs:
>This is probably an erroneous concept. The mutation in primates
>disabling the GLO gene for endogenous ascorbate probably occurred
>one fine day many millions of years ago, and quite rapidly spread
>after all that extra energy was freed up, giving an advantage to
>the new dietary ascorbate-dependent primates. It would probably
>take only a dozen generations to displace the older nonmutants.

You outline that the disabling of the ascorbate-gene occured
as a single mutation "one day millions of years ago".
This is probably right. The advantage out of this (less energy into
ascorbate production) may spread in a few dozend generations in the
vicinity.
But this can result in a lasting change *only* if for a long time
the ascorbate supply from food is constantely high.
Because you need the time that all other individuals of the species
need the time to die off.

Imagine, if the environment changes into a supply shortage for only a
few years, then the missing vitamin for the mutants will result in a
*drastic* disadvantage for them. If anywhere in whole africa a small
group of hominid *with* vitamin-c synthetisation ability was left, then
these will have a drastic advantage above what you call mutatns.

This is why I assume the high-supply times of vitamin-c  must have been
very long. Long enough that *all* hominids with vitamin-c synthetisation
(non-"mutants") could have died off. Or be displaced by mutants by only
a relatively small advantage by sparing the synthetisation metabolism.

There are quite many animals living in a fruit-rich environment, but only
few evolved without own ascorbate. Why did only primates evolve so?

What further implications does such a long and constant vitamin-c rich
nutrition (probably from fruit) have on our food adaption?
What about the fructose? Fruit minerals? The other fruit vitamins?

Amadeus