account of his experiences in the Malay Archipelago, and how at one
time he caught a female orang-outang with a new-born baby, and the
mother died, and Wallace brought up the baby orang-outang by hand;
and this baby orang-outang had a kind of infancy which was a great
deal longer than that of a cow or a sheep, but it was nothing
compared to human infancy in length. This little orang-outang
could not get up and march around, as mammals of less intelligence
do, when he was first born, or within three or four days; but after
three or four weeks or so he would get up, and begin taking hold of
something and pushing it around, just as children push a chair; and
he went through a period of staring at his hands, as human babies
do, and altogether was a good deal slower in getting to the point
where he could take care of himself. And while I was reading of
that I thought, Dear me! if there is any one thing in which the
human race is signally distinguished from other mammals, it is in
the enormous duration of their infancy; but it is a point that I do
not recollect ever seeing any naturalist so much as allude to.

It happened at just that time that I was making researches in
psychology about the organization of experiences, the way in which
conscious intelligent action can pass down into quasi-automatic
action, the generation of instincts, and various allied questions;
and I thought, Can it be that the increase of intelligence in an
animal, if carried beyond a certain point, must necessarily result
in prolongation of the period of infancy,--must necessarily result
in the birth of the mammal at a less developed stage, leaving
something to be done, leaving a good deal to be done, after birth?
And then the argument seemed to come along very naturally, that for
every action of life, every adjustment which a creature makes in
life, whether a muscular adjustment or an intelligent adjustment,