John Graunt was the first person to compile data that showed an excess of male births over female births. He also noticed spatial and temporal variation in the sex ratio, but the variation in his data is not significant. John Arbuthnott was the first person to demonstrate that the excess of male births is statistically significant. He erroneously concluded that there is less variation in the sex ratio than would occur by chance, and asserted without a basis that the sex ratio would be uniform over all time and space.
Campbell, R. B.
"John Graunt, John Arbuthnott, and the Human Sex Ratio,"
4, Article 11.
Available at: http://digitalcommons.wayne.edu/humbiol/vol73/iss4/11