Re: Evolution of human diet

Julian Vincent ((no email))
24 Nov 1995 04:19:37 GMT

This note is shorter than I'd like 'cos I just lost a huge reply when my
computer crashed . . .
Basically the human mouth is a high-force / low-displacement device for
processing food. It copes best with brittle foods (i.e. break at low
displacements) which can be quite hard (e.g. nuts, veg, etc) but it can't
cope easily with materials which are _very_ hard (e.g. small grains) or
which have to be deformed a long way before they break or are fibrous and
insensitive to stress-concentrations (that's materials science talk -
sorry!). Grass and meat both fall into this latter category.
The only way to adapt these foods to the human mouth is to process them.
You can rot them (i.e. be a scavenger) or cook them. Cooking allows you
to change the texture of grains (they are made into a crisper, somewhat
softer cellular structure) and to reduce the deformation necessary to
impose on meat before you can break it in the mouth. No-one has worked
out how to break down grass leaves other than get a cow to do it for you.
All this opens up a load of new foods for man. Could this be where man
started getting a real evolutionary advantage, because he could process
food and therefore live in a far wider range of habitats and off a
greater variety of foods?
I'll stop before I crash again!!
Julian Vincent