Re: evolutionary success of humans


<pauldepstein@xxxxxxx> wrote in message
news:dlrpsb$1p47$1@xxxxxxxxxxxxxxxxxxxxxx
>
> I am a little bit puzzled by our evolutionary success because we have
> an enormous number of relative disadvantages compared to other mammals.
> Here are just a few of them.
>
> 1) Long gestation period.

Necessary for the development of a brain and body that can live for over 70
years I think. It's a good balance for child-rearing. A shorter gestation
would result in more children and a more unmanageable litter, and a longer
one would impair the ability of the woman to work and travel as easily.

> 2) Almost no multiple births.

Once again, the workload of childrearing is probably the reason.

> 3) Bad hearing.

Bad in comparison to other mammals, but perhaps only because it wasn't as
high on the list of evolutionary priorities as others. The balance of
traits only has to be as good as what's needed for a survival advantage.
Some individuals score very high in particular sensory tests, so it's likely
that at some time in the past, some of our ancestors had evolved superior
senses, but in the bigger picture, they weren't important enough to be kept
by all.

Color blindness is very common, perhaps because the ability to see all
colors isn't a big enough survival advantage for those without it to be
selected against. Not having a trait that isn't critical, is a bit of an
advantage, because it requires less energy and time in fetal development,
and in the case of a sensory ability, it demands less on the brain to
process the signals.

> 4) Poor mobility -- slow on land, and terrible at swimming and
> climbing.

A human has remarkable long-distance endurance when compared to other
animals, such as horses, antelope and moose. In fact, a human on foot can
eventally overtake most animals in a long distance run. That is in fact a
hunting technique used by primitive hunters.

> 5) Terrible sense of smell.
>

Again, evolutionary priorities.

> Paul Epstein
>
>


.