reply to Matt D: evolution, stature, nutrition...

Lisa Rogers LROGERS at EMAIL.STATE.UT.US
Tue Jul 11 16:59:45 MDT 1995


------------------- EVO711 follows --------------------
Thanks, Matt, for the kind words about my "forebearance", but I
never mind explaining things when asked or when I think education
is possible.  I find that actual [or alleged] data and logic can shed
light rather than heat.  Without a foot in concrete specifics, the
thoroughly abstract and ultra-skeptic arguments often fall apart.


I think I have already covered the general picture of human body
size change in recent centuries, with the example of immigration
to US, and resultant increased caloric intake while young, etc, as
I was taught it.  Some of the variation before the industrial era is
surely likely to have occurred by similar mechanisms.

Now I think that some of the interest in the topic of nutrition here
is in terms of "was-it-better before or after or during capitalism."
I admit I haven't thought of it much in those terms before.  Now
that I do, I'm not sure that I see grounds for any sweeping
generalization can be made that way, because "it depends" on
several other things as well.

Marx in Capital I is great with researched records of food intakes
of working people in England in the previous several centuries,
where he shows that contemporary factory workers were eating
much less than their peasant ancestors.  Obviously, that capitalism
was bad for the nutrition of a lot of people.  But were peasants
eating more or less than previous hunter-gatherers?  I don't know,
except that it's not that simple.  Foraging people have often been
shown to be well-nourished [contrary to one stereotype].  They
often gain and lose weight on a yearly cycle, but within a lean and
healthy range, say +/- 10 pounds.  But so do low-tech, non-subsidized farmers.

The problem with farming is that one cannot just pick up and
follow the rain.  Dependence on specific plots of land and
sedentary ways means that when there is a bad year, it is very bad
indeed.  Even one year of drought wreaks havoc in terms of
mortality and fertility rates.

There has been some archeology done on nutritional differences
within a stratified society.  Mostly, it sounds pretty familiar; those
with poor burials [no fancy goods] sometimes show signs of hard
labor, high injury and disease rates and malnutrition [not measured
by size, height and weight, but in bone density, cellular
morphology and chemistry.]  I also heard about a peculiar reversal
from a Mayan dig - the highest socially ranked appeared to be
smaller and malnourished.
One obvious remark may be well, what will future archeologists
think when they dig up a nice fat twentieth-cent. family with one
anorexic adolescent who obviously starved to death?  I mean, there
are probably insoluble puzzles, especially when there are some
things that are not preserved among the stones and bones.

On the other hand, I am now putting this together with what little
I know of Mayan art, and I have anothr idea for that particular
puzzle.  Based on the wall-paintings and some carved writing, we
know that mayan religion involved frequent blood-letting.  Not the
mass execution/sacrifices of the Aztec style.  It was something like
offering a sacrifice [indeed!] to cut one's own tongue deeply and
let it bleed a bowl-ful.  Talk about nutritional stress!  Maybe this
is linked to the "starving" aristocracy - the loss of expensive
matter/energy from a lifeform is similar to not getting that
matter/energy to begin with, in addition to the loss of the
physical/biochemical labor/energy that was required to transform
raw materials into blood.  Not even to mention the immediate
problem of getting oxygen transported to tissues!  Why would they
do it?  Social regard is a material reward, or I could say, it is
attached to many material rewards.

Re: the "Ice Man" of the Alps, I think he's around 5 thousand years
old.  I recommend National Geographic mag. coverage and PBS
(US pub. tv) PBS did a great documentary on him.  But this brings
up another issue:

When was the most recent "ice age"?  I was taught to think of the
end of it around 10-12,000 yrs bp [before present] in US, but also
that the common notions of an ice age are often far from the facts.
Large amounts of North Am and Europe were not covered by ice,
and rather little of it covered by year-round ice.  Any parts that
were would have been quite non-habitable for nearly all life-forms;
no plants = no herbivores = no carnivores or omnivores like us.
After all, what's the mega-bison gonna eat?  Average temp. was
only a few degrees lower than it is now.

The pleistocene is about the last 100,000 years and it is all full of
ice ages, as glaciers enlarged and traveled further down canyons
and mountains, and then retreated each and every year.  Ice
coverage increases over all only if glaciers advance more than they
retreat, on average, over a given time period.  There have been
several large advances lasting 10s of thousands of years and many
more small ones in between.  There is no reason to think that there
will not be more of them, i.e. we are in an "inter-glacial" period
like many others.  I'm sure a temporal map of extent of ice looks
just like maps of mean global temp. and rainfall patterns - chaos,
of a sort.

On the other hand, ice-age is sometimes intended (by those outside
the field) to mean Neanderthal, or as an euphemism for "cave-man"
or something.  Well, the line between Neanderthal and modern type
bones does not match the borders of any paricular ice-age, as far
as I know.  In fact, it is a huge and fascinating puzzle in itself as
to what the hell happened, and the switch from Neanderthal to
modern-type is at different times in different places.  In fact, there
are not-quite-modern bones in many places, while Neanderthal
sensu classico is European only.  But I think it is reasonably clear
that in NW Europe, such as France, i.e. at sites in the Neander
valley for example, that Neanderthal types were gone and
"Cro-Magnon" [named for another French site] which is now
considered modern-type Homo sapiens had appeared around 30,000
yrs bp.  (They are found earlier in other places, including Africa.)

Anyway, the point I am finally getting to is that Neanderthals are
known for being "more robust" than moderns, in terms of thickness
of bones and the related musculature.  What ever they were up to,
it apparently required strength and exertion on a fairly regular
basis.  They have other interesting features as well, such as a
somewhat larger brain [in relation to body size] than modern types,
including us.  I don't think their heights were unusual (but this is
not my best subject.)

Another relevant point about "ice-age/s" is that it makes no
difference I can see if we think of 5000 bp as being part of an ice-age or not.

But now let me leave Matt D. with a few questions about his
question about "social selection".  Well, first, I'm not sure what you
mean by "runaway feedback mechanisms".  Then, it's not entirely
clear what you mean by "social selection".

I think you combine two or more seperable concepts: 1. Is "natural
selection" acting presently among humans?  2. and if not, "then
does natural selection really have any meaning at the level of the
individual human  organism"?

What do you mean by "meaning"?  What difference do you think
it should make in #2 if #1 is answered either way?

I've addressed #1 somewhat before by saying that genetic change
in a population which is due to differential survival / reproduction
is evolution by selection.  Note that this definition does not
distinguish between "natural" selection and "social" selection.
Perhaps it was a mistake on my part not to point this out more
often, but I say "natural" in traditional use of Darwin's powerful
metaphor, because he was explaining NS by comparing it to
"artificial" selection, as practiced by people upon livestock, i.e.
selective breeding.

Also, I have mentioned that I don't think of natural as opposed to
social.  (These kinds of things contribute to our "speaking different
languages.")  Darwin coined the term "sexual selection" for
differential reproduction due to variation in obtaining mates or the
resources of a mate, which could be thought of as a kind of social
selection.  But I don't think of SS as opposed or even distinct from
"natural" selection.  Rather, I'd put selection in general, or NS, or
call it Darwinian Selection, as the most inclusive category, and
everything else as diversity within that unity.

Some anthros and others would have been happy to make this post
shorter by saying of course there is no NS anymore on humans, but
they usually do that by separating "social" effects from "natural",
as in the assertion that "humans have changed their own
environment" so nothing is natural anymore.  I can't do that.
Instead, I am using a way of thinking that cuts across those
traditional categories.

As for "anyone can survive and reproduce", I beg to differ!  Right
here in US there is a nearly two-fold difference in life expectancy
between different neighborhoods [data on Chicago] not even
counting homicide!  Infant mortality rates vary up to 5-fold
between different neighborhoods here in Salt Lake City, and every
other large city.  Men have a high variance in number of
descendants, higher than women.

Even if it were true that everyone "can survive and reproduce", it
is differential reproduction that is the name of the game.  More
descendants are always 'better', as it increases one's genetic
contribution to future generations.  Even if we all had equal
reproduction now, that would not prevent us each from trying to
get ahead more.  This includes efforts to get offspring into good
positions for further production of descendants.  A non-reproductive offspring is useless, in terms of evolution (unless they
can reproduce indirectly by assisting the reproduction of their own
close kin.)

Thanks much for the postings,
Lisa Rogers



Matt D. posted not so very long ago, and I excerpt below:

>>> Matt D. <afn02065 at freenet.ufl.edu>  6/28/95, 03:42pm >>>
... "modern (darwinian-mendelian) synthesis vs. lamarckism"...  is
about as open to debate as Creation "Science" vs. actual science.
I  think Lisa has been more than forebearing in her responses...

Medieval Europeans were midgets compared to modern
first-worlders.  My  understanding is that this is mainly a function
of nutrition (including  having enough to eat).
.... some folks have suggested that ice-age Europeans (whoever the
people who were in Europe during the ice age may have been)
were pretty tall  and robust.  .....

"Runaway feedback mechanisms" aside, I'd be curious as to what
Lisa has to  say about social selection, at least for human beings.
Is it a meaningful  concept from a biological/anthropological
perspective?  I mean, it seems  that almost anyone can reproduce,
with a high chance of survival for at  least some of their
offspring--even if they are congenitally disabled.  So  if basically
anyone can survive, even if not pleasantly, then does natural
selection really have any meaning at the level of the individual
human  organism (Bell Curve fascist fantasies aside, of course)?

-- Matt D.





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