From the biological standpoint the probability of gregariousness being a primitive and fundamental quality in man seems to be considerable. As already pointed out, like the other great enlargement of the biological unit, but in a much more easily recognizable degree, it would appear to have the effect of enlarging the advantages of variation. Varieties not immediately favourable, varieties departing widely from the standard, varieties even unfavourable to the individual may be supposed to be given by it a chance of survival. Now the course of the development of man seems to present many features incompatible with its having proceeded amongst isolated individuals exposed to the unmodified action of natural selection. Changes so serious as the assumption of the upright posture, the reduction in the jaw and its musculature, the reduction in the acuity of smell and hearing, demand, if the species is to survive, either a delicacy of adjustment with the compensatingly developing intelligence so minute as to be almost inconceivable, or the existence of some kind of protective enclosure, however imperfect, in which the varying individuals were sheltered from the direct influence of natural selection. The existence of such a mechanism would compensate losses of physical strength in the individual by the greatly increased strength of the larger unit, of the unit, that is to say, upon which natural selection still acts unmodified. A realization, therefore, of this function of gregariousness relieves us from the necessity of {23} supposing that the double variations of diminishing physical and increasing mental capacity always occurred _pari passu_. The case for the primitiveness of the social habit would seem to be still further strengthened by a consideration of such widely aberrant developments as speech and the æsthetic activities, but a discussion of them here would involve an unnecessary indulgence of biological speculation. IV. MENTAL CHARACTERISTICS OF THE GREGARIOUS ANIMAL. (_a_) Current Views in Sociology and Psychology. If we now assume that gregariousness may be regarded as a fundamental quality of man, it remains to discuss the effects we may expect it to have produced upon the structure of his mind. It would be well, however, first, to attempt to form some idea of how far investigation has already gone in this direction. It is of course clear that no complete review of all that has been said concerning a conception so familiar can be attempted here, and, even if it were possible, it would not be a profitable enterprise, as the great bulk of writers have not seen in the idea anything to justify a fundamental examination of it. What will be done here, therefore, will be to mention a few representative writers who have dealt with the subject, and to give in a summary way the characteristic features of their exposition.