Page:Popular Science Monthly Volume 46.djvu/397

Rh deadly poisonous snakes. The terror they inspired was so great that there can be no wonder at its survival in the human female of to-day.

Another habit, a relic of what was indulged in for a definite beneficial purpose, remains to the present day—namely, the fondness of children for rolling. It points to the time when our ancestors possessed hairy bodies tenanted by colonies of parasites, and is another example of parasite irritation shaping animals' habits, alluded to above. These hairy bodies were the homes of many parasites, among which the parents of Pulex irritans and many another Pulex, together with other kinds which need not be specified, were very much in evidence; and then our ancestors, owing to less perfect articulation of joints, or to less perfection in development of the limbs, or to the thick covering of hair, were unable to reach the source of trouble effectively, and could, like horses or donkeys, only alleviate the irritation by rolling. Scratching of the head as a nervous habit, from the association between nervous irritation and actual irritation by parasites, which must also be transmitted to the brain by the nerves, is a relic of similar ancestral parasitically infested animals. It persists now among human beings who are doubtless above suspicion in the matter of unwelcome tenants; and it is a familiar expression of doubt and perplexity among οί πολλοί who may not be altogether so guiltless.

According to the Darwinists, the loss of hair from the body, which man has suffered in comparison with simial ancestors, is attributable to the benefit he has derived from being able to get rid of his parasites, or from the greater advantage he obtained in the struggle for existence owing to being less troubled with parasites, whose numbers diminished from want of "cover." Such an idea, however, confuses cause and effect in a most remarkable manner. The diminution of parasites is a result of the loss of hair, but it certainly is not the cause of the hair being lost. To make it so is similar to saying that the diminution of trees in newly settled countries is caused by a decrease in the number of wild beasts. It supposes that the greater freedom from parasites was so important to simial ancestors who lost their hair as to give them immense advantage in the struggle for existence, forgetting that this does not explain the cause of the loss of hair in the first place. With loss of hair once started, some such benefit may be granted; but what caused the loss of hair in the first place? "Spontaneous variation" is no answer at all; what is the cause of the spontaneous variation? This seems too early a stage at which to say Ignosco or Ignoro.

Then this parasite idea ought to be applied to what is going on at the present day—to the loss of hair from the head—but