Re: chimps stronger than humans

In reference to: > How does Neandertal, and Cro Magnon for that matter, fit
into
this framework? Both had very large brains in hyper-robust bodies."

I think living in cold environments requires extra DHEA. The individuals
who could not provide sufficient DHEA to provide resistance body
temperatures, died. Extra DHEA would provide increased growth and
development of the brain and body. (The next text is intended as further
explanation.) This principle may also explain why ice age animals grew
larger. However, if a species is in a position whereby testosterone may
also be selected, then this increased testosterone may amplify the effects
of cold-induced DHEA. Hence, the Neandertals exhibited exaggerated sizes,
produced, I suggest, by the early groups being concentrated in specific,
cold areas. Concentration, I suggest, causes selection for testosterone.
Since gorillas and orangutans are large and live in the tropics, I would
think their increase in size is more of a testosterone effect. If anyone
responds to this, they will probably mention "Bergmann' Rule." If an animal
increases in size due to extra DHEA triggered by cold and reaches a limit in
DHEA production, then the extra DHEA is used for warth at the expense of
size. So animals farther north become smaller as a result. (Now, to answer
another question likely to be generated by the foregoing, I think chimps are
smaller than gorillas and orangs due to increased testosterone in the
"common ancestor" of chimps and humans. That is, the female in the common
ancestor increased in testosterone which exposed the brains of their fetuses
to increased testosterone. This began the process of producing a brain
which competed better for available DHEA. Hence, chimps and humans produce
more testosterone than gorillas and orangs but are smaller.) James Michael
Howard


"Tom McDonald" <tmcdonald2672@xxxxxxxxxxx> wrote in message
news:rvIDl.15076$Jf5.365@xxxxxxxxxxxxxxx
James Howard wrote:
(...a try to see if I can post... could not the past few days...)

It is my hypothesis that all tissues rely on DHEA for optimal function of
all tissues, especially the brain. Therefore a competition exists for
available DHEA. I think the brain evolved during mammalian evolution to
increase its ability to take DHEA. Hence, the large brains of mammals.
Further, I think primates evolved because of increased use of DHEA by the
brain due to exposure fetal brain sizedue to exposure to increased
testosterone in female primates. Extended, then humans evolved because
of dramatically increased maternal testosterone which may be "seen" when
female hominids increased in size relative to males.

Testosterone increases androgen receptors which absorb DHEA. Therefore,
as the brain increases in size due to increased absorption of DHEA, there
is less DHEA for other growth and development. Hence, as brain size
increases the body decreases in robustness at the same time.

How does Neandertal, and Cro Magnon for that matter, fit into this
framework? Both had very large brains in hyper-robust bodies.

Chimps produce less testosterone and more DHEA; their brains are smaller
and their muscles are stronger.

((If interesed, see chart of testosterone in the primates, top, right of
http://www.anthropogeny.com/evolution.html and my published papers re
mammalian, primate, and human evolution.)

James Michael Howard


--
Tom

When Tyrants tremble, sick with fear,
And hear their death-knell ringing;
When friends rejoice, both far and near,
How can I keep from singing.


.

Relevant Pages

  • Re: chimps stronger than humans
    ... available DHEA. ... I think the brain evolved during mammalian evolution to ... I think primates evolved because of increased use of DHEA by the ... dramatically increased maternal testosterone which may be "seen" when female ...
    (sci.anthropology.paleo)
  • Re: chimps stronger than humans
    ... all tissues, especially the brain. ... available DHEA. ... I think primates evolved because of increased use of DHEA by the ... dramatically increased maternal testosterone which may be "seen" when female ...
    (sci.anthropology.paleo)
  • Re: chimps stronger than humans
    ... It is my hypothesis that all tissues rely on DHEA for optimal function of all tissues, especially the brain. ... I think primates evolved because of increased use of DHEA by the brain due to exposure fetal brain sizedue to exposure to increased testosterone in female primates. ...
    (sci.anthropology.paleo)
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    ... Bipolar Disorder, DHEA and Testosterone in Women: ... These hormones are connected with mania, depression, and menstrual ...
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