Re: AAT Theory

Paul Crowley (
Tue, 03 Oct 95 00:20:16 GMT

In article <44p3g9$> "Lisbeth Andersson" writes:

> A few years ago I saw an article in Scientific American (in their
> "science 100 years ago" column), where they referred to an experiment
> about how well newborn human babies could hold on to things. The
> result was that they are surprisingly good at it. The scientist(s) 100
> years ago noticed that babies, if given something to grasp, would
> hold on hard enough that it was possible to lift them with no other
> support.
> This was with babies who had to lift a lot more weight from their
> heads than any early hominid.
> Yes they had only two arms, as opposed to four limbs, to grasp with.
> But why do you assume that the arms were weak?

You will often see primate adult females, such as chimps, running,
climbing, brachiating, etc. and then notice that they have a small
baby attached. Those babies need four clinging limbs to hold on.
This capacity has enormous survival value for the infant (and also
for the mother) in all ordinary activities such as foraging and
escaping predators, and even at night while sleeping.

The clinging reaction in newborn human babies is well-known, and is
unquestionably a evolutionary remnant. AFAIR it fades in a week or
so. I don't think anyone would suggest that bipedal hominid infants
could cling on in the same way, or that an arms-only clinging
capability would have any real survival value.