Page:Popular Science Monthly Volume 46.djvu/393

Rh strange. The baby is decidedly bowlegged, but this shape of leg would be exactly that necessary for tree-climbing quadrumana. When it is first stood up, the baby puts only the outer parts of its feet to the ground, and turns its toes in. It does not allow its heels to touch the ground. When a monkey walks on a branch it does not allow the homologous part to our heel to touch the branch. When a dog sits, as we call it, to beg, it really brings the same part into contact with the ground as we do in standing. It brings its hocks (heels) fiat to the ground, and supports its weight oil the hocks and toes. Children are very fond of "sitting on their heels" in the same manner as a dog when it begs. The difference between the begging attitude of a dog and the standing of a child is in the straightening of the knee joints in the latter. As a dog has not the power to straighten the knee joint, because of its quadrupedal habits, it can not stand on its hocks as we can; as soon as it raises its body on its hind legs it elevates the hock from the ground. The power to straighten the knee joint, and so to put the hock to the ground, is not inherent in babies at first; it is only by practice in walking that they are able to acquire it. Why, if babies' ancestors have always been animals walking on their hocks, should these processes have to be gone through?

The movements and habits of a young baby seem so strange to us because they are so different from those made by adults, and because they are so unconsciously performed. Joy is expressed by muscular movements, by wriggling of the hands and toes, or by convulsive beatings of the arms, when it is small; by "jigging," when it is larger. These movements are expressive of joy because to any animal of highly developed muscular energy movement is absolutely essential, and particularly pleasing, while stillness is the reverse. It is muscular excitement, chiefly no doubt electrical, a heritage from ancestors who knew not what it was to be still, that gives that restlessness to children and causes them to find so much pleasure in mere motion and muscular exertion of any kind. Jumping for joy is very literally correct of a child's expression of pleasure. The prospect of a sweet will excite a series of leaps to indicate delight; and they further serve the purpose of relieving the tedium of waiting the half-second necessary to the donation. The pleasure of finding a bird's nest with eggs in it—a pleasure which must have been very real sometimes in the case of hungry monkeys and savage man, but is now only a survival of the instinct thus formed—this pleasure a boy expressed by a series of convulsive leaps into the air; and during the performance not only were the arms and legs moved as much as possible, but the muscles of the stomach and vocal organs had to be utilized to cause accompanying shouts. It may be remarked that in adults, when limb-movements are less active, shouts are.