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Show 38 THE DESCENT OF 1\iAN. PART L being performed during many generations, become converted into instincts and are inherited. They may then be said to be degraded in character, for they are no longer performed through reason or from experience. But the greater number of the more complex instincts appear to have been gained in a wholly different manner, through the natural selection of variations of simpler instinctive actions. Such variations appear to arise from the same unknown causes acting on the cerebral organisation, which induce slight variations or individual differences in other parts of the body; and these variations, owing to our ignorance, are often said to arise spontaneously. We can, I think, come to no other conclusion with respect to the origin of the more complex instincts, when we reflect on the marvellous instincts of sterile worker-ants and bees, which leave no offspring to inherit the effects of experience and of modified habits. A.lth~ugh ~high deg.ree of intelligence is certainly compatible With the existence of complex instincts as we s.ee in the insects just named and in the beaver, it is not Improbable that they may to a certain extent interfere with each other's development. Little is known about the f~ctions of the brain, but we can perceive that as ~he mtellectual powers become highly developed,. the v~r10:1s parts of the bra~n must be connected by the most mtncate channels of mtercommunication; and as a consequence each separate part would perhaps tend to become less well fitted to answer in a definite and uniform, th~t ~s instinctive, manner to particular sensations or assoCiatwns. I have tho:Ught this digression worth giving, because w~ may ~aslly underrate the mental powers of the h1gher a~Imals~ and especially of man, when we com-pare their actwns founded on the memory of t even t s, on f oresi·g h t, reason, and imagination, wpaitsh CHAP. II. 1\iENTAL POWERS. 39 exactly si:Uilar a~tions. instinctively performed by the lower . ~mmals; m .this lat~er case the capacity of performmg such actwns havmg been gained, step by step, through the variability of the mental organs and natural selection, without any conscious intelligence on the part of the animal during each successive generation. No doubt, as Mr. Wallace has argued/' much of the intelligent work done bv man is due to imitation and not to reason; but there is ·this great difference between hi~ actions and many of those performed by the lower amma1s, namely, that man cannot, on his first trial, make, for instance, a stone hatchet or a canoe, through his p?wer of imitation. He has to learn his work by practice; a beaver, on the other hand, can make its dam or canal, and a bird its nest, as well, or nearly as well, the first time it tries, as when old and experienced. To return to our immediate subject: the lower animals, like man, manifestly feel pleasure and pain, happiness and misery. Happiness is never better exhibited than by young animals, such as puppies, kittens, lambs, &c., when playing together, like our own children. Even insects play together, as has been described by that excelle~t obser~er, P. Huber,6 who saw ants chasing and pretendmg to bite each other, like so many puppies. The fact that the lower animals are excited by the same emotions as ourselves is so well established that it w~ll not be neces~ary to weary the reader by ~any details. Terror acts m the same manner on them as on u~, causing the. muscles to tremble, the heart to palpitate, the sphmcters to be relaxed, and the hair to stand on end. Suspicion, the offspring of fear, is eminently characteristic of most wild animals. Courage : :Contributions to the Theory of Natural Selection,' 1870, p. 212. Recherches sur les M:oours des Fourmis,' 1810, p. 173. |