In a previous post, Bob Avery had the following question,

"In response to Brian MacLean's questions, Loren Cordain wrote:

>hunter gatherers (n=229) listed in Murdock's Ethnographic Atlas, the
>median and modal values for animal food subsistence is 56-65% whereas
>the median and modal value for plant food subsistence is 26-35%.

Loren, just to clarify, when these percentages are bandied about, are we
referring to  (1) caloric values, (2) volume, or (3) weight?"

                Murdock did not stipulate this information in his
compilation of the Ethnographic Atlas; he simply referred to the data as
"subsistence dependence".  He compiled his admittedly rough numbers from
ethnographic observations made by anthropologists and ethnographers who in
most cases neither weighed the food nor attempted to estimate its caloric
value.  If one examines the original publications cited by Murdock (there
are about 400 references total), many of the references pre-date caloric
theory, therefore, it is likely that most of the observations were made by
rough visual estimation of volume and/or weight.  Consequently, there is an
inherent imprecision in the conversion of these estimates to caloric values.
However, this is the nature and shortcomings of ethnographic data & since,
these hunter gatherer societies no longer exist (in their aboriginal state),
the ethnographic observations represent the only information available on
the nutrient intake of these societies.   I suspect that Murdock realized
these shortcomings, and his estimates have been divided into fairly large
ranges for each class interval (i.e. 16-25%, 26-35% etc).

                Dr. Kern makes some excellent points in his post of November
14th regarding selection for longevity in the paleo- environment.  Many of
these same points have been eloquently written up by Jared Diamond (Diamond
J.  Why women change. Discover Magazine 1996 (July):131-37).
                The persistence of female menopause in our species is a
powerful example in which post-reproductive selection pressures influence
the gene pool.  Females of our species are quite unusual in the animal
world; except for a single species of whale, no other mammal experiences
menopause.  How is it that natural selection could have ever selected for
early shut down of reproductive capacity before the end of the full
lifespan?  Surely, women with a longer reproductive span will produce more
offspring and thereby increase the probability of increasing the number of
their genes in the gene pool.  Thus, any theory attempting to explain
menopause must show that by making fewer babies, in actuality more babies
are made (i.e more of the mothers genes survive with the surviving
offspring).
                Infants of older mothers are  increasingly unlikely to
survive or be healthy, because the risks of abortion, still birth, low birth
weight and genetic defects rise as the mother grows older.  Thus, not only
are the children of  older mothers more likely to die, but the  chances of
the older mother  dying in or after childbirth are also increased.  Further,
as a woman gets older she is also likely to have accumulated more children,
consequently her survival directly impacts the survival not just of her
present child, but of her previous children.   Thus, each succeeding
pregnancy not only puts her at risk, but also all of her previous children.
By shutting down reproduction before the end of the lifespan (menopause),
apparently more of the mothers children, and hence her own genes will
survive.  In hunter gatherer societies, a woman's survival is not only
important to her children, but also to her grandchildren.  Studies of
hunter-gatherer grandmothers show that they share their excess gathered food
harvest with grand children and grown children.  Consequently, in the case
of humans, natural selection appears to be acting in an unusual a priori
manner in which the ultimate reproductive (total individual genes in the
gene pool) potential is acting post-reproductively.
                Humans are different from other animals in that we have a
culture and language in which we can transmit knowledge about our
environment (present and past) to our offspring which may influence their
survival and hence our own genes' survival.  Because old people represent
the repository of knowledge in pre-literate societies, they can influence
the survival of hundreds of people who bear their genes by providing
information during times of stress (eg. where to find water or plants when
the 40 yr drought arrives).  In hunter-gatherer societies, the old person is
the tribe's library.  The old person knows more about the local environment
than anyone else and is the sole person with accurate knowledge of events
that happened long ago.  The accumulated experience that the elderly
remember is important to the survival of the entire tribe.  Hence, because
of our culture and ability to transmit knowledge, we in effect have an a
priori influence upon genes which we can no longer influence merely by
direct transmission (i.e reproduction).


Cordially,



Loren Cordain, Ph.D., Professor
Department of Exercise and Sport Science
Colorado State University
Fort Collins, CO 80523
tel: (970) 491-7436
fax:(970) 491-0445
email:[log in to unmask]
http://www.colostate.edu/Colleges/CAHS/ess/cordain.htm