Jacques Laurin wrote:

>Such adaptation, however, takes many generations ; the genetic code changes
>very slowly over time (less than 1 % in the six million years since our
>>forebears diverged from the chimpanzees). The practice of cooking is
>quite >recent...

It's not the genetic code that's changing here but the DNA sequences that
regulate the expression of and code for proteins (i.e. enzymes).  The often
quoted 1% or 2% figure between humans and chimpanzees is an average (of
single copy, coding DNA) with some genes being identical and others being
more divergent (see Sibley and Ahlquist 1987).  Also, not all DNA base
changes are equivalent; a single base change that results in an amino acid
replacement in the active site of an enzyme can drastically alter or
diminish function while many changes in other parts of the molecule may
have only a slight effect.

>there is a reason to ask :
>
>whether a genetic adaptation has been or would have been necessary

If cooking creates novel compounds that are otherwise not found then
perhaps genetic changes would be required.  If cooking only alters the
availability of compounds that are naturally present (by destroying some
and making others more available) then no.  (This IS an active area of
anthropology research.)

>whether such adaptation is possible

Sure it's possible.

>whether it has had time to occur

This depends on the selection pressure.  If there is a lot of selection
pressure then changes can occur quite rapidly in evolutionary time (see
Messier and Stewart 1997).

>Non-original foods introduce molecules into the organism to which the enzymes,
>programmed by the genetic code, have no reason to be adapted. These
>>"non-original molecules" may be created in chemical reactions induced by
>>cooking, or may come from foods not in the original alimentary spectrum
>of >humans (such as animal milk).

Infants ARE supposed to consume animal (human) milk and are adapted to
digest it.

>In other words, the culinary intoxination will give rise to a "molecular
>>pathology" which could constitute the cause in whole or in part of
>numerous >illnesses.

COULD, perhaps but this is just speculation.  It's just as likely that any
new molecules created by cooking would be metabolized by the enzymes that
have evolved over millions of years to deal with all kinds of
bio-molecules.  Just because a specific compound is new doesn't necessarily
mean it can't be processed.  Also, it seems that cooking would be more
likely to break down existing molecules rather than create new ones.  I'm
frankly far more concerned with the multitudes of synthetic chemicals that
have been introduced into our food and environment over the last 100 years.


Randall Collura

Sibley, C. G. and J. E. Ahlquist (1987). "DNA hybridization evidence of
hominoid phylogeny: results from an expanded data set." J Mol Evol 26(1-2):
99-121.

Messier, W. and C. B. Stewart (1997). "Episodic adaptive evolution of
primate lysozymes." Nature 385(6612): 151-4.

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