anyone with references on this issue?

Mon, 2 May 1994 17:25:23 -0500

I wonder if it is really as easy to lose a complex biochemical
system as some of the respondees to the Vitamin C question suggest.

In complex systems many of the subcycles utilize enzymes found in other
systems. Thus, by changing or eliminating these enzymes other cell
systems are effect. In addition, many of the intermediary products
act as substrates in other systems, and their absence may produce
problems for the organism. Lastly, if a system is effected at one
of its intermediary steps, the substrate no longer acted upon by the
appropriate enzyme may acculumate to toxic levels.

It was suggested that 60million years is adequate to lose a system
through evolution. If all the primates lack the ability to manufacture
Vitamin C, then it is the ancestral group, apparently during the
cretaceous, which lost this ability. Therefore, we don't know how long
it really took. On the other hand, what evidence is there that early
mammals actually had this capacity?

Scurvy is quite rare in human populations. Excluding the rather dramatic
but very infrequent sea voyages in the past, scurvy is generally only found
with other deficiencies and is a sign of general nutritional shortages. But
humans are not really frugivorous.

What is the distribution of Vitamin C synthesis which actually supports the
notion that you lose it if you don't use it?

spencer turkel
life science dept.