But one must ask: “Did man’s Simian ancestor really loaf away so much of his time in this dull manner? and was the running-off of rain so frequent and imperative a need as to make him set to work to invent this special adaptation?”
After some millions of years have passed since his day we are not in a position to go beyond speculations, and this one seems barely credible, moreover, it is quite unnecessary, as certain following facts will show.
Steps of the Inquiry.
Having expounded the text and its context, I would mention that in 1897 I came across these views of biologists as to the very strange arrangement of hair on man’s forearm, and was struck with the inadequacy of the theory of Darwin, Wallace and Romanes to account for the state of things which every man can find, if he looks for it, on his own forearm. I examined a large number of apes and monkeys so as to test the theory, and the results were published in Nature, Vol. 55, under the title “Certain vestigial characters in Man.” Suffice it to say that from the evidence I brought forward one had to choose between two heresies: either to deny the Simian ancestry of man or to affirm the inheritance of some acquired characters; and I chose the latter. The choice of “evils” or heresies which had to be made then will serve as an introduction to all that follows.
This article was followed by a paper at the Zoological Society of London on “The Hair-Slope in certain Typical Mammals,” and after this came a paper at the same Society, giving evidence and reason why certain patterns of hair in some mammals should rank as specific characters. Various other papers at the Anatomical Society of Great Britain and Ireland were read and published and others at the Zoological Society, in which different regions of the hairy coat of man and lower mammals were dealt with. In 1903 the whole subject of the Direction of Hair in Animals and Man was treated in a book freely illustrated.
I then followed the advice of Horace and left the subject alone for nine years, during which time my further observations and reflections served but to confirm, except in two or three unimportant details, the results and conclusions in the book and papers of an earlier date. The connection between the habits of an animal and the distribution of its hairy coat were always cropping up, and I saw then and see now no possible explanation of the connection than that the former is the efficient cause of the latter.
How the Hair is Arranged on the Forearm.
Returning now to the text, the remarkable arrangement of hair on man’s forearm, attention may be directed to the accompanying figure of the forearm of a lemur, an ape and man, in which the extensor or back view of this limb-segment is shown, the heavy “war-arrows” being employed to direct the attention of the reader to the main lines in which the hair-streams flow. The front or flexor surfaces in the lemur and ape are not shown because they are precisely like the corresponding back surfaces, and the flexor surface in man is shown in the figure. The figures are so much like diagrams that a very little detailed description will suffice. For the examination of the hair on man’s forearm the best subject is a dark-haired youth, and it is easily traced, though in any hairy subject it can be shown up well by placing the forearm in water for a minute and allowing the water to drain off. The normal and congenital hair-slope on the forearm is then well displayed.
On the front surface of man’s forearm the hairs point away from the elbow and divide in the middle of the surface into two streams, one passing to the outer and the other to the inner border in a downward gentle curve, and they join the streams of hair on the back surface. In this pattern there is nothing very peculiar, for it is shared by many monkeys.
When the back surface is examined it is found to present an arrangement of the hair which is unique among hairy mammals. The figure shows the eccentric course taken by the hair on the back surface. In the centre, exactly along the extensor border of the ulna, from the wrist to the point of the elbow, the hair-stream has been bold enough to turn straight upwards in a narrow line, and it was here that our three great leaders saw their chance of claiming for Selection a tiny bit of territory, a kind of Duchy of Luxembourg between two great States, though, as I proceed to show, the claim is disallowed and untenable.