A relative age effect in men's but not women's professional baseball: 1943-1954.

Birthdates of professional female and male baseball players active from 1943 to 1954 (the beginning and final years for professional female leagues) were matched for year of birth and league years and then compared by birth quarters, with a cutoff date beginning August 1. A relative age effect was noted for males, as there was a significantly different distribution of players across birth quarter, but there was no such effect for female professionals. Since players were matched for birth year and league play, the difference was unlikely to be due to seasonality differences in birth.

Sopranos but not tenors live longer.

The longer life spans of females compared to males has been attributed to the effects of sex hormones. Since experimental tests of this possibility in humans are unethical, indirect studies have been relied on for evidence. The present study offers such indirect evidence by comparing life spans of female and male opera singers, since sex hormones are known to influence development of voice.