Traditional knowledge--knowledge, that is, imparted by one generation to the next--is common enough amongst the higher of the lower animals, and forms no inconsiderable part of their mental equipment. Thus we may see the hen teaching her chickens how to seek food, and the cat instructing her kitten how to ambush mice. Birds and mammals inhabiting desert islands have none of that fear of man which in our country they acquire from dire experience. We have a saying, “as wild as a hawk”; but Darwin relates how he almost pushed a hawk from its perch with his gun in the Galapagos Islands. Round our coasts the sea-birds are exceedingly shy; in a harbor they feed from the hand. Formerly the Arctic seals, impelled by fear of bears, inhabited the outer margin of the floes; at the present day they have retreated from the more dangerous neighbourhood of man to the landward edge. Antarctic seals, harried by the great carnivora of the ocean, are watchful in the water; on land or on the surface of the ice, where till lately they met no danger, they may be slaughtered like sheep in a shambles. They are capable of profiting by experience; but they are slow to learn, and can acquire but little. Judged by our human standard, they are very stupid. The means of escape adopted by Arctic seals, and the means of capturing them, the ships and guns adopted by man, furnish a measure of the intellectual difference. [Sidenote: Slavery in the World of Insects] When animals are social, and so have the opportunity of learning, not only from their parents, but from other members of the species, the power of making useful mental acquirements is correspondingly great. It reaches a remarkable degree of development even amongst insects, some species of which live together in great communities. Young ants, for example, are tended with anxious care. It is said that they are led about the nest and instructed by older individuals. They are reported to be playful. Most significant of all is the fact that some species have the habit of capturing slaves belonging to other species, which they take as pupæ, never as adult ants, and to whom, as they develop, they teach their duties. The slaves are neuter individuals, and have no offspring, the supply being maintained by fresh captures. It follows that the slaves must _learn_ their work, and therefore that their performance of it is not instinctive, but intelligent. It is a fair inference that many of the so-called instincts of ants are really acquired habits, bits of knowledge and ways of thinking and acting which are handed down from one generation to the next, not by actual inheritance, but traditionally and educationally, just as children receive from us language, or religion, or a trade. Indeed, there is reason to believe that the power of making mental acquirements has evolved to a greater degree in the favourable environment of the ant-nest than among any other species except man. [Sidenote: Man’s Essential Instincts]