NATURE 



241 



THURSDAY, JULY 14, i{ 



EVOLUTION OF THE MORAL INSTINCT. 

 The Origin and Growth of the Moral Instinct. By 

 Alexander Sutherland, iM.A. Two vols. Pp. xiii + 461, 

 and vi + 336. (London : Longmans, Green, and Co., 

 1898.) 



MR. SUTHERLAND'S work is thoroughly Dar- 

 winian, being based on a huge mass of observ- 

 ations which he has selected without apparent bias, mar- 

 shalled well, and handled judiciously. Few books written 

 since Darwin's time on the evolution of the human mind, 

 are so thorough and comprehensive and well deserving 

 of study. Its chief merit lies in the solid treatment 

 by which the writer confirms and extends the masterly 

 sketch drawn by Darwin in the fourth and fifth chapters 

 of his " Descent of Man," but it is also extremely original 

 in many particulars ; and though somewhat diffuse here 

 and there, is interesting throughout. Mr. Sutherland 

 resides in Australia, where it must have been more 

 difficult to obtain that ready access to books and 

 authorities which European students enjoy, and to 

 obtain skilled help in his experiments ; he is therefore 

 entitled to a proportionate increase of praise and to much 

 excuse where he is open to criticism. 



The main argument and the general results of his 

 inquiry may be stated in a few words, but the fulness of 

 their significance will be miperfectly realised without 

 carefully reading the whole of his book. They are, that 

 a progression in complexity of organisation and faculty 

 is closely associated with the duration of growth, in 

 eluding both the embryonic stage and that of im- 

 maturity. Next, that the duration of growth is closely 

 correlated with parental care. It is shown that in the 

 earlier stages of evolution of a species, the parental care 

 is small, but as higher stages of evolution are reached, 

 the amount of parental care successively increases until 

 it grows into parental sympathy, and he argues that it 

 is directly or indirectly from parental sympathy that all 

 morality proceeds. The first of these three steps might 

 rank as a corollary to Von Baer's law, namely that the 

 successive stages in the history of each race are hurried 

 through during the embryonic life of each individual in 

 it. Consequently as the number of stages increases, the 

 length of time required for individual development tends 

 to increase also, though not in the same proportion 

 because the rate of passing through them may and does 

 to some extent become more rapid. The author shows 

 by a large array of evidence that the above presumption 

 is true, and that this essential basis of his further argu- 

 ment may be accepted without hesitation. 



Leaving insects aside as creatures of an entirely 

 different mental constitution to our own, and as evolved 

 along different lines from vertebrates, he begins by 

 tracing in detail the first appearances of the parental 

 instinct in various species of fish. He finds— 



" Of species that exhibit no sort of parental care, the 

 average of forty-nine gives 1,040,000 eggs to a female 

 each year ; while among those which make nests or any 

 apology for nests the number is only about 10,000. 

 .Among those which have any protective tricks, such as 

 NO. 1498, VOL. 58] 



carrying the eggs in pouches, or attached to the body, 

 or in the mouth, the average number is under 1000 ; 

 while among those whose care takes the form of a uterine 

 or quasi-uterine gestation which brings the young into 

 the world alive, an average of fifty-six eggs is quite 

 sufficient. 



" It must hence be very evident how much better are a 

 few that are tended than a great crowd left without care. 

 And the first link in the chain of reasoning of this book 

 is that in the struggle for existence an immense premium 

 is placed upon parental care, and that not until this has 

 been developed can the higher nervous types become 

 possible." 



There is another well-known way, as he points out, by 

 which the life of the young is rendered more secure, 

 namely by assuming mimetic characters and thereby 

 escaping the observation of enemies. But successful 

 mimicry leads to nothing further, and therefore does not 

 enter into the plan of the present work. 



He next examines into the case of amphibians and 

 concludes that — 



"Among all the non-parental species for which I have 

 obtained information the number exceeds 800 eggs, yet 

 the average of nine species that show parental care is 

 only twenty-seven. Among the viviparous species the 

 number of offspring declines to ten or less in the year." 



Up to this point he considers that the story of evolution 

 contains no indication whatever of the existence of real 

 affection, but the true parental sympathy, which is 

 destined to play a most important part in the survival of 

 the nobler species, arises during the next stage. 



Birds and mammals are understood to be developed 

 from different points in the scale of reptile life, and the 

 character of the protection they respectively give to their 

 young differs accordingly. Some reptiles incubate their 

 eggs, and birds carry on this process of incubation ; 

 other reptiles bring forth their young alive, and mammals 

 follow that method. As their respective types advance 

 in the scale of intelligence and affection, he shows that 

 both birds and mammals present a lengthening period 

 of parental protection, but the mammalian method reaches 

 far ahead of that of the birds. It leads to the monkey, 

 to the savage and to civilised man ; the other seems to 

 reach its acme in the bower bird. 



In discussing birds, he divides them into three classes 

 of progressive intelligence. The lowest contains the 

 ostrich, emu, »&c., which annually lay on the average 

 twelve or thirteen eggs ; the medium class includes 

 partridges, petrels, coots, plovers and pigeons, these 

 lay, on the general average, seven or eight eggs ; the 

 highest class includes birds of prey, parrots, wood- 

 peckers, sparrows and finches, these lay, on a general 

 average, four or five eggs a year. All birds of the higher 

 grade 



" hatch out young ones of abject helplessness, and the 

 continuance of each species is absolutely dependent upon 

 that parental love which is poured out in floods of un- 

 measured self-sacrifice. Among these birds the gracious 

 charm of family life is first made fully known, and it is 

 no mere chance that, concomitant therewith, comes that 

 delight in throbbing melody which proclaims the fullest 

 tide of joyous life. In all these genera, with their 

 multitudinous species, male and female unite in their 

 care for the tender brood, and show, as a rule, a steady 

 attachment each for the other. Sometimes the male and 



M 



