The evolution of sex / by Professor Patrick Geddes and J. Arthur Thomson.

  • Patrick Geddes
Date:
1889
Catalogue details

Licence: Public Domain Mark

Credit: The evolution of sex / by Professor Patrick Geddes and J. Arthur Thomson. Source: Wellcome Collection.

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    established and enhanced as secondary sexual characters of the species. The process by which the possessors of the fortunate excellencies of beauty and strength outbid or overcome their less endowed competitors, he termed sexual selection. It is only fair, however, to state Mr Darwin's case by direct quotation. Sexual selection depends on the advantage which certain individuals have over others of the same sex and species solely in respect of reproduction. ... In cases where the males have acquired their present structure, not from being better fitted to survive in the struggle for existence, but from having gained an advantage over other males, and from having trans- mitted this advantage to their male offspring alone, sexual selection must have come into action. ... A slight degree of variability, leading to some advantage, however slight, in reiterated deadly contests, would suffice for the work of sexual selection. ... So too, on the other hand, the females have, by a long selection of the more attractive males, added to their beauty or other attractive qualities. ... If any man can in a short time give elegant carriage and beauty to his bantams, according to his standard of beauty, I can see no reason to doubt that female birds, by selecting during thousands of generations the most melodious or beautiful males, according to their standard of beauty, might produce a marked effect. ... To sum up on the means through which, as far as we can judge, sexual selection has led to the development of secondary sexual characters. It has been shown that the largest number of vigorous offspring will be reared from the pairing of the strongest and best-armed males, victorious in contests over other males, with the most vigorous and best- nourished females, which are the first to breed in the spring. If such females select the more attractive, and at the same time vigorous males, they will rear a larger number of offspring than the retarded females, which must pair with the less vigorous and less attractive males. So it will be if the more vigorous males select the more attractive, and at the same time healthy and vigorous females; and this will especially hold good if the male defends the female, and aids in providing food for the young. The advantage thus gained by the more vigorous pairs in rearing a larger number of offspring, has apparently sufficed to render sexual selection efficient. Another sentence from Darwin's first statement of his position
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