SEX-RATIO, COITAL RATE, HORMONES AND TIME OF FERTILIZATION WITHIN THECYCLE

In this paper I shall consider the relationships between coital rates, timing of fertilization within the cycle, and sex ratios of the resul ting offspring. It will be suggested that there is: (1) Analytic (math ematical) evidence for a correlation between coital rate and time of f ertilization. (2) Empirical evidence for a correlation between time of fertilization and sex ratio of offspring. Whence there arises: (3) A correlation between coital rate and sex ratio secondary to correlation s of both with time of fertilization. These variables will be consider ed in these pairs in order. Section 4 will be devoted to the magnitude of the correlation between coital rate and sex ratio. Lastly it will be noted that the data on these two variables cohere not only with tha t on timing of insemination, but with the overall hypothesis that pare ntal hormone levels at conception are causally associated with sex rat ios at birth.