In all that has been written against Darwin’s _Descent of Man_ there is perhaps nothing that is so relevant to the main issue as Mr. Hudson’s criticism. He observes that Darwin has gathered together from all regions of the globe unconnected facts about various species without closely examining the habits and actions of these species.[349] It goes without saying that such an examination would be extremely difficult with regard to animals, the social life of which is as yet so insufficiently known. For one not a zoologist, at least, it would be too audacious to present any classification of the instances, and therefore we did not even mention this possibility in the treatment of animal art. In this connection, however, one may suggest, without positively asserting, that perhaps even the animal manifestations of dance and music may be classified in groups which correspond to the prevailing social conditions of the respective species. There is at least a striking similarity between the types of song, serene with all their passion, with which the males of the monogamous songsters entertain their mates—those mates which, if one may believe the brothers Müller, have been chosen even before the pairing season.[350] And, on the other hand, these graceful and harmonious utterances stand in the strongest contrast to the vehement display of promiscuous wood-birds and polygamous fowl. However presumptuous it may be to draw any general conclusions from these coincidences, it is evidently indispensable, when treating of sexual selection in man, to look for some connection between the various forms of courtship and prevailing social institutions. This necessity was fully understood by Darwin himself.[351] But it has been too much overlooked by his successors, who, when discussing his thesis, have defended or attacked it by promiscuous collections of facts in which barbaric Malays and degenerate Polynesians are quoted alongside primitives like the Veddas and Fuegians. If this confusion is disentangled by a proper arrangement of the instances according to stages of culture, the seeming inconsistency of the ethnological evidence will be removed.