The centre in the cerebrum which controls
the use of the hands is on the fringe of the region which seems
to be concerned in mental operations. For reasons which will
appear presently, we may add that the centres for controlling the
muscles of the face and head are in the same region. Any finer
training or the use of the hands will develop the centre for the
fore limbs, and, on the principles, may react on the more
important region of the cortex. Hence in turning the fore foot
into a hand, for climbing and grasping purposes, the primitive
Primate entered upon the path of brain-development. Even the
earliest Primates show large brains in comparison with the small
brains of their contemporaries.
It is a familiar fact in the animal world that when a certain
group enters upon a particular path of evolution, some members of
the group advance only a little way along it, some go farther,
and some outstrip all the others. The development of social life
among the bees will illustrate this. Hence we need not be puzzled
by the fact that the lemurs have remained at one mental level,
the monkeys at another, and the apes at a third. It is the common
experience of life; and it is especially clear among the various
races of men.
Pages:
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436