Re: "Human ancestors born big brained"

On Nov 15, 11:24 am, Paul Crowley <dsfdsfd...@xxxxxxxxxxxx> wrote:
caldervang...@xxxxxxxxx wrote:
Anyway, I disagree a little bit with you on one point.  If a
female dies during childbirth because the head of the baby ...
for whatever reason... won't pass...

Note that you begin the above sentence with
an 'IF'.

then that IS a very important factor in
evolution... ie, survival and reproduction.
So the head/brian size imposes a limiting factor;

Then you  reach a few conclusions, forgetting
the "IF".

okay, i'll take your point. how about "she dies" instead of "if she
dies..." or whatever...
childbirth for humans (and apparently H.N.) is risky.


IF a significant number of females died in
childbirth from the head getting stuck, then it
would be a limiting factor.  But, even in the
usually highly-unnatural modern state of things,
head-sticking is rare.  If the first pregnancy
was, nearly always, in teen-age years,  and the
first child often lost (for any of the usual
reasons, made more likely by the mother's
youth and inexperience) and IF the female was
then pregnant or nursing for almost all her
reproductive years, with high infant mortality
(from all the usual reasons) the incidence of
such events (neonates getting stuck in the
birth canal) would be very low indeed.

we moderns have an extended infancy in
order to grow our brains bigger outside the womb.  

This is the nonsense to which I object.
It is based, almost entirely, on a set of
self-praising assumptions.

My work, day in day out, is with infants and toddlers. I am not self-
praising, just observing. Compare a human infant to, say, a newborn
deer. The deer can stand up and run off in a few minutes. We don't
walk/move for about 6 months.


Childbirth has been and remains a relatively risky thing for
moms and babies... which is not seen as frequently in the
other animals.

True -- other animals generally seem to have
lower risks.

If humans infants were normally born after
six months in the womb, there would be almost
no problems around childbirth.  Foetuses are,
in fact, almost fully formed at six months.
But they spend another three months inside,
growing larger, putting on weight and, above
all, building up a layer of fat.

It is THAT which requires explanation, not
some silly nonsense about brain size.

I agree. Cf. my discussion with Jois a few years ago. The baby fat
is NOT just for nutrition; after a short period (a few days) of fat
consumption in a starvation event, the infant body starts to "eat"
muscle tissue. Jois and I agreed to disagree on this point. I have
the science on this one though... evidence in a court case....

Anyway, I do agree with the "silly nonsense" that there was in our
evolution some sort of limiting selection between brain size,
gestation and birth. Why do we need bigger brains anyway?
regards
chap


Yes, occasionally the shoulders get stuck.  Most moms and
midwives will not think much about that in comparison to passing
the head

Are the opinions of moms and midwives
particularly relevant here?  The emergence
of the head shows that things are progressing
normally, and it seems a very important stage
which can be greeted with relief.  But is that
really justified -- when the main problem is
the baby's shoulders getting stuck?

even in breech births.

Breech births can (I gather) be much more
of problem.  In normal births an infant's
head can be readily distorted, and pass
through easily, whereas this is not possible
in breech births.

Paul.

.

Relevant Pages

  • Re: "Human ancestors born big brained"
    ... female dies during childbirth because the head of the baby ... ... Paul, ... juncture in human reproduction. ...
    (sci.anthropology.paleo)
  • Re: "Human ancestors born big brained"
    ... female dies during childbirth because the head of the baby ... ... reasons, made more likely by the mother's ...
    (sci.anthropology.paleo)
  • Re: How do "Right-To-Lifers" justify...
    ... they are, in fact, conscious human lives. ... So when you were an infant did your mother drop you on your head? ...
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  • Re: Going back in time
    ... that was the reason I've been a M/C nut all my life. ... My mother dropped me on my head as an infant on a train bound for Chattanooga. ...
    (rec.motorcycles.harley)