(2) The gregariousness of the pack is variable; probably, amongst wolves, it was much greater anciently than it is to-day. There are conflicting statements about the gregariousness of wolves that have been studied in different countries. Couteulx de Canteleu (France) says: “The wolf is an enemy of all society; when they assemble it is not a pacific society, but a band of brigands.”[41] Thompson Seton (Canada) says: “Wolves are the most sociable of beasts of prey; they arrange to render one another assistance. A pack seems to be an association of personal acquaintances, and would resent the presence of a total stranger.”[42] Gregariousness of wolves must be reduced by failure of game (as by the destruction of bison in North America), and still more by the encroachments of civilisation (as in France). The primitive human pack, probably, was more constantly gregarious than wolves are: (_a_) because its individuals, having no instinctive or traditionary knowledge of hunting, were more dependent on co-operation; and (_b_) because the long youth of children made it necessary for parents to associate with the pack during their nurture—else no pack could have existed; for whilst wolves are nearly full-grown at eighteen months, apes are not mature until the eighth or ninth year. At a later period, after the invention of effective weapons, an individual became, for many kinds of game, less dependent on co-operation; but by that time, the hunting-grounds of a pack were circumscribed by those of other hostile packs; so that no one dared go far alone. (3) With gregariousness went, of course, (_a_) perceptive sympathy—every animal read instantly in the behaviour of others their feelings and impulses; (_b_) contagious sympathy—the impulses of any animal, expressed in its behaviour, spread rapidly to all the rest; and (_c_) effective sympathy, so far (at least) as that all united to defend any associate against aggression from outside the pack. Perceptive and contagious sympathy, however, extend beyond the limits of the pack or the species. Most of the higher mammalia can read the state of mind of others, though of widely different kinds, in their expression and behaviour; and many are liable to have their actions immediately affected by signs of the emotional impulses of others, especially fear. These modes of sympathy, therefore, though liveliest amongst gregarious animals, are not dependent on specific gregariousness.