In 1908 mathematician G. H. Hardy of Cambridge University and general practitioner and obstetrician Wilhelm Weinberg of Stuttgart independently discovered what came to be known as the "Hardy-Weinberg equilibrium (Hardy–Weinberg principle). This
"states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. These influences include non-random mating, mutation, selection, genetic drift, gene flow and meiotic drive. Because one or more of these influences are typically present in real populations, the Hardy–Weinberg principle describes an ideal condition against which the effects of these influences can be analyzed."
"Mendelian genetics were rediscovered in 1900. However, it remained somewhat controversial for several years as it was not then known how it could cause continuous characteristics. Udny Yule (1902) argued against Mendelism because he thought that dominant alleles would increase in the population. The American William E. Castle (1903) showed that without selection, the genotype frequencies would remain stable. Karl Pearson (1903) found one equilibrium position with values of p = q = 0.5. Reginald Punnett, unable to counter Yule's point, introduced the problem to G. H. Hardy, a British mathematician, with whom he played cricket. Hardy was a pure mathematician and held applied mathematics in some contempt; his view of biologists' use of mathematics comes across in his 1908 paper where he describes this as "very simple".
"The principle was thus known as Hardy's law in the English-speaking world until 1943, when Curt Stern pointed out that it had first been formulated independently in 1908 by the German physician Wilhelm Weinberg. William Castle in 1903 also derived the ratios for the special case of equal allele frequencies, and it is sometimes (but rarely) called the Hardy–Weinberg–Castle Law" (Wikipedia article on Hardy-Weinberg principle, accessed 12-16-2013).
Hardy, "Mendelian Proportions in a Mixed Population," Science 28 (1908) 49-50.
Weinberg, "Über den Nachweis der Vererbung beim Menschen," Jahr. Ver.f. Vaterland Nat. Würz. 64 (1908) 369-82.