Re: Diet and Evolution


Malcolm wrote:
"camelopard" <camelopard@xxxxxxx> wrote
I am puzzled by the statements of some dietary supplement advocates,
which I take to be true statements, that certain vitamins, minerals, amino
acids, etc. are not present sufficinetly in foods to meet the daily needs
of
the human body, even if we eat an enormous amount of the providing foods,
and thus we have to take supplements.

This doesn't seem to make evolutionary sense. It seems that the human
body should receive ample nutrients from the foods it is able to digest.

How would one answer this? Is the same true for other species, or just
for humans?

Are some foods adapted not just for humans, but for the diet of other
animals? So does the human body just get more or less of what it needs?

Perhaps the human body is adapted to a diet followed by early humans
and
monkey-like ancestors, and perhaps for most of its evolutionary history
the
human or pre-human body was much smaller, and perhaps more metabolically
adjusted to its food, and did not require supplements.

Or maybe the human diet has always been deficient. Does that mean the
human body is unnatural? Or maybe the original foods have been destroyed,
and we have only nutritionally imperfect substitutes, that fall short of
what is required.

Oh, well. This is getting complicated. I wonder what the question was?

There is an awful not of pseudo-science and debased science in the nutrition
business.

Basically a statement such as "vitamins are good for you" might be given a
scientific dressing, but it conceals a fundamentally magical, non-scientific
way of thinking, dragging in all sorts of concepts about "the natural" and
what it means to be a healthy person.

Your central proposition that were are evolved to eat a fairly normal diet
of meat and fruit, without supplements, is correct. Humans are actually very
versatile eaters and can live an on a huge range of foods, from the
predominantly meat-based diet of the Inuit to the wholly vegetarian one of
the Hindus. What is controversial is where there are alleged minor long-term
effects for certain types of diets.

Generally there is a big advantage in going from a serious deficiency to a
mild deficiency, a small advantage in going from a mild deficiency to an
optimal amount, and the benefit of going from an excess to an optimal amount
is smaller still. A Westerner is unlikely to have a serious deficiency of
anything. However he may well have some excesses, for instance of fats or
salt.

Vitamins and other supplements are largely a waste of money. There might be
a few individuals they help, but basically if we want to improve modern
diets we do it by reducing rather than increasing intake.
--
Buy my book 12 Common Atheist Arguments (refuted)
$1.25 download or $7.20 paper, available www.lulu.com/bgy1mm

Health food industry is pretty ripe with pseudo science and bogus
claims.

There are some facts. We lack the ability to make vitamin C. In our
evolutionary history, some of our ancestors lost the ability to make
vitamin C, but they got enough in their diets so that this defect was
likely fixed by genetic drift.

For vitamin C there is an adequate dose that most people can get from
what they eat, but more may be better in some respects. Natural
selection is sort of based on the concept of good enough to get by.
Something may make the organism better in some respect, but if you are
dealing with a threshold trait, it might not matter if you can run 42
miles an hour when 40 miles an hour is good enough to get the job done.
Can you see as well as a hawk?

You might be able to get adequate amounts of vitamins from what you
eat, but everyone in the population is stuck with basically the same
diet (in the wild, and not dependent on what you can afford or choose
to buy in the supermarket). This does not mean that more of some
vitamins may have no further benefits, it just means that, that is all
the animal has been able to get, and that is all that natural selection
has had to work on.

Ron Okimoto


.

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