Re: current path of human evolution


<pauldepstein@xxxxxxx> wrote in message news:dme828$153s$1@xxxxxxxxxxxxxxxxxxxxxx
>
> Perplexed in Peoria wrote:
>
> > You would also have to show that the people with unplanned pregnancies
> > have more children than people who plan their pregnancies.
>
> Interesting. I thought that assumption was "obviously correct." You
> think it is "very unlikely." I agree that it is an assumption which
> needs looking into.
>
> I have met a large number of women (in Texas) who had children at ages
> 16 to 18. I think it's likely that these pregnancies were (to some
> extent) unplanned but these weren't close friends of mine so I didn't
> ask such personal questions. My assumption is that, having their first
> child at such a young age, they will be more likely to have more
> children than those who consistently plan their pregnancies. However,
> of course, this type of anecdotal reasoning is extremely unreliable --
> like everyone else, my assumptions depend on my background and
> experience, and I'm just trying to explain how I arrived at my
> (unsupported) assumption.

Understood. My somewhat anecdotal experience has been that women who
have first children at a young age are LESS likely to enter a stable
marriage and raise lots of children.

In any case, we are both basing our anecdotes on a small fraction of the
world's population - western civilization.

> Interestingly, I'm not the only one who has made a (perhaps spurious)
> connection between unplanned pregnancy and human evolution. What
> follows is not an exact quote but a very close paraphrase of something
> I read by Steven Pinker:
>
> "If an edible plant was found to have contraceptive properties, we
> would evolve such that the plant was poisonous to us."
>
> It seems to me that Pinker is making a similar assumption to me;
> however, we could both be wrong.

That contraception is not favored by natural selection is a commonplace
observation. I am a little surprised that Pinker would suggest that
NS would favor death (by an allergic reaction) to temporary sterilization
as a result of ingesting the plant - perhaps he only meant to suggest that
we would evolve to find the plant extremely distasteful.

> > Also, you seem to be suggesting that this is a new feature in human
> > evolution. Since when? Since effective contraception? Seems a little
> > counter-intuitive to me.
>
> I believe that the advent of effective contraception has dramatically
> changed the nature of human evolution.
> This really does seem completely obvious.

And I completely agree.

> A new-found ability to have
> sexual intercourse without pregnancy is a fundamental biological change
> in the human condition. Any fundamental change in a species is likely
> to have evolutionary consequences.
>
> So I'm very surprised by your word -- "counter-intuitive". What
> exactly is counter-intuitive, and why?

I would think that the primary evolutionary impact of contraception would
be to DECREASE the frequency of those types of people who tend to use it.
Perhaps we are in agreement on this, but you tend to see such people as
risk-averse. I tend to see them as self-absorbed.

There has always been a force in human evolution favoring those who wish
to raise large traditional families over those choosing other life styles.
The advent of effective contraception has merely enhanced the effectiveness
of this force.


.

Relevant Pages

  • Re: current path of human evolution
    ... > You would also have to show that the people with unplanned pregnancies ... > have more children than people who plan their pregnancies. ... connection between unplanned pregnancy and human evolution. ...
    (sci.bio.evolution)
  • Re: current path of human evolution
    ... > Since a very large proportion of human pregnancies are unplanned, ... > continue to grow very rapidly, and (if future generations continue to ... > Human evolution may have reached an interesting path because the traits ... However, such traits (risk-taking, ...
    (sci.bio.evolution)