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Show 302 THE PRINCIPLES OF PART II. -excess of male over female births is less when they are illegitimate than when legitimate.35 In various parts of Europe, according to Prof. Faye and other authors, "a still greater preponderance of " males would be met with, if death struck both sexes "in equal proportion in the womb and during birth. " But the fact is, that for every 100 still-born females, " we have in several countries from 134·6 to 144·9 '' still-born males." Moreover during the first four or five years of life more male children die than females; ·" for example in England, during the first year, 126 •: boys die for every 100 girls,-a proportion which in "France is still more unfavourable." 36 As a consequence of this excess in the death-rate of male children, and of the exposure of men when adult to various dangers, and of their tendency to emigrate, the females in all old-settled ·countries, where statistical records have been kept,37 are found to preponderate considerably over the males. It has often been supposed that the relative ages .of the parents determine the sex of the offspring; and Prof. Leuckart 38 has advanced what he considers 35 Babbage, 'Edinburgh Journal of Science,' 1829, vol. i. p. 88; also p. 90, on still-bor~ children. On illegitimate children in England, :see' Report of Registrar-Genern1 for 1866,' p. xv. 36 'British and Foreign lVIcdico-Chirurg. Review,' April, 1867, p. :-H3. Dr. Stnrk also remarks(' Tenth Annual Report of Births, Deaths, &c., in Scotlanrl,' 1867, p. xxviii) tlmt "These examples m\)-y suffice " to shew that, at almost every stage of life, the males in Scotland ~'have a greater liability to death and a higher death-rate than the ·" females. The fact, however, of this peculiarity being most strongly •: developed at that infantile period of life when the dress, food, and ' general treatment of both sexes are alike, seems to prove that the "higher male death-rate is an impressed, natural and constitutional "peculiarity due to sex alone." ' 37 With the savage Guaranys of Paraguay, according to the accurate Azara ('Voyages dans !'Amerique merid.' tom. ii. 1809, p. 60, 179), the women in proportion to the men are as 14 to 13. as Leuckart (in Wagner, 'Handworterbuch der Phys.' B. iv. 1853, s. 774. CHAP. VIII. SEXUAL SELECTION. 303 sufficient evidence, with respect to man and certain domesticated animals, to shew that this is one important factor in the result. So again the period of impregnation has been thought to be the efficient cause ; but recent observations discountenance this belief. Again, with mankind polygamy has been supposed to lead to the birth of a greater proportion of female infants; but Dr. J. Campbell 39 carefully attended to this subject in the harems of Siam, and he concludes that the proportion of male to female births is the same as from monogamous unions. Hardly any animal has been rendered so highly polygamous as our English race-horses, and we shall immediately see that their male and female offspring are almost exactly equal in number. Borses.-Mr. 1'egetmeier has been so kind as to tabulate for me from the 'Racing Calendar' the births of race-horses during a period of twenty-one years, viz. from 1846 to 1867; 1849 being omitted, as no returns were that year published. The total births have been 25,560,40 consisting of 12,763 males and 12,797 females, or in the proportion of 99·7 males to 100 females. As these numbers are tolerably large, and as they are drawn from all parts of England, during several years, we may with much confidence conclude that with the domestic horse, or at least with the race-horse, the two sexes are produced in almost equal numbers. 1'he fluctuations in the proportions during successive years are closely like those which occur with mankind, when a small and thinly-populated area is considered : thus in 1856 the male horses were as 107·1, and in 1867 as only 92·6 to 100 females. In the tabulated returns the proportions vary in cycles, for the males exceeded the females during six successive years ; and the females exceeded the males during two 39 Anthropological Review, April, 1870, p. cviii. 40 During the last eleven years a record has been kept of the number of mares which have proved barren or prematurely slipped their foals; and it de!erves notice, as shewing how infertile these highly-nurtured and rather dosely-interbred animals have become, that not far from one-third of the mares failed to produce living foals. Thus during 1866, 809 male colts and 816 female colts were born, and 743 mares failed to produce offspring. During 1867, 836 males and 902 females were born, and 794 mares failed. |