On Mon, 20 Apr 1998 Jennie Brand Miller
<[log in to unmask]> wrote:
>
> Why is it that many scientifically trained people think hunter-gatherers
> regularly starved to death, allowing natural selection of the 'thrifty
> genotype' (one susceptible to overweight and obesity today)?  Is it true
> that we often starved - what is the evidence?

And on Mon, 20 Apr 1998 Ruediger Hoeflechner
<[log in to unmask]> wrote:

> Is a thrifty geno/phenotype really a hominid acquisition that gives us
> information about food scarcity in the last four million years? Isn't it a
> much older vertebrate strategy to survive long periods of low food
> availability? In captivity most vertebral species - including chimpanzees
> and gorillas - suffer from obesity and other "western diseases" if fed ad
> libitum. Is starvation (to death?) common amoung great apes?

It seems to me that for there to be a selective effect it does not have to
be starvation to death, but a level of starvation which prevents
successful reproduction - any capacity to reproduce in the face of food
shortages would be advantagous.

My immediate question is: do these overweight captive animals also suffer
from diabetes?


Jennie also wrote:

> It puzzles me that humans could become taller and taller throughout the
> paleolithic while simultaneously being exposed to fluctuating but
> significant periods of starvation.  I'd like to hear your comments?

Adult height is determined both genetically and by childhood nutrition, so
that with increasing nutrition in the western world today each generation
is taller than the last.  However the differences over the palaeolithic
(the last 2.5Ma)  also involve species differences where there may be a
variety of selective effects acting.  One major factor is likely to have
been the introduction of cooking which reduces the energy required for
digestion and therefore allows a greater proportion of dietary energy to
be directed into growth.  Increasing brain size presumably lead to greater
hunter efficiency, through strategy changes and improved hunting
equipment.  In the Upper Palaeolithic (last 40ka) we begin to to see
regional (and wider)  exchange networks which may have provided some
cultural back-up to finding food resources in times of localised food
scarcity.

Age at death may also affect the final apparent height of populations, as
a poorly nourished individual will continuing growing for a longer period.
In C19th England the lowest social classes did not attain maximum height
until 29 years of age [1].  So if adult life expectancy* were low in
palaeolithic hunter-gatherers, and nutrition was poor, then we might
expect to underestimate the final adult height, as our sample will include
a number of adults who are still growing.

* that is the life expectancy of those reaching an age of 18.

[1] Mays, S (1998) The archaeology of human bones. London & New York:
Routledge.  p70

Andrew

 =========================================================================
 Dr. Andrew Millard                              [log in to unmask]
 Department of Archaeology, University of Durham,   Tel: +44 191 374 4757
 South Road, Durham. DH1 3LE. United Kingdom.       Fax: +44 191 374 3619
                      http://www.dur.ac.uk/~drk0arm/
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