The Courtship of Animals

by W. P. Pycraft

One is puzzled at what seems a concession of Darwin’s to the Lamarckian theory of the inherited effects of use in this connection. For in discussing the bellowing of the stag in “The Descent of Man,” he remarks that it “does not seem to be of any special service to him, either during courtship or battles, or in any other way. But may we not believe that the frequent use of the voice, under the strong excitement of love, jealousy and rage, continued during many generations, may at last have produced an inherited effect on the vocal organs of the stag, as well as of other male animals?” All the evidence goes to show that the production of sound, and the instant interpretation of its significance, is a matter of the highest importance. In the case of the Moose, for example, the noise occasioned by the cleaning of antlers provokes the same frenzy as at another time is aroused by the voice. Dullness of perception not only in these matters, but at all times, is fatal.

As touching the less conspicuous secondary sexual characters of Deer more must be said presently. For the moment the antlers must retain our attention. Time was when the Deer lacked these appendages. When they first appeared, in the now extinct species of the Middle Miocene period, they were no more than short prongs. Later, one of the prongs became elongated, and developed short branches or “tines,” which, in succeeding species, became more numerous, while at the same time, with the gradual evolution of more and more species, these antlers assumed new features both in the matter of size and in the character and number of the “tines,” a development which has reached its maximum to-day. But apart from these specific variations, which have given us such types as those of the Roe-deer, Red-deer, Wapiti, Caribou, Moose, Fallow-deer, Sambar, Schombergk’s deer, the strange Milou-deer, Elds-deer and Mule-deer, each species displays a quite remarkable range of variation in regard to its particular type of antler. Nowhere, perhaps, is this more strikingly marked than in the case of the Caribou and Moose. No doubt this feature is due largely to the fact that the horns are shed annually, and that the variations are due, in part at any rate, to temporary environmental conditions, such as food and weather. But these apart, individual peculiarities are constant, reappearing with more or less exactness each year.

Plate 6.

Photo by Lord Delamere, from “The Living Animals of the World.”

GROUP OF BEISA ORYX.

The lance-like horns of these animals can be used with deadly effect, even against lions.

[Face page 60.

In contemplating these facts one asks: What are the underlying factors of this variability? What is the significance of the branching? What end is attained by the annual shedding? That the antlers constitute very effective weapons of offence there can be no doubt, and one is inclined to regard the branching as the outcome of natural selection, on the assumption that branched antlers would be less deadly than lance-like weapons. It would perhaps be tempting to accept this interpretation as all sufficient were it not for the evidence afforded by the hollow-horned ruminants. The Oryx and the Kudu, for example, are lance-bearers, and therefore show conclusively that stags similarly armed might well have continued to survive in spite of the foils which the “tines” provide. Darwin, long since, guardedly suggested that while these weapons primarily served for offensive purposes, their elaborate systems of branching might have been brought about by sexual selection. That is to say, the extreme beauty of the weapons may excite the admiration of the females as well as our own. Granting this, he inferred they might have played an important part in elaborating the branching by constantly displaying a preference to mate with those males possessed of the largest and most branched antlers. But there are many and serious objections to this suggestion, and the most important of all is the fact that the female is allowed no choice in the selection of her lord and master. We can, then, only regard the antlers of deer as another instance of the survival of a “fortuitous” but inherent variation, which survived because, whatever the defects thereof, they proved advantageous in the struggle for existence.