Although Darwin himself observed that inbred features of fancy pigeons were inherited in accordance with Mendel's laws (although Darwin didn't actually know about Mendel's ideas when he made the observation), it was not obvious that these features selected by fancy pigeon breeders can similarly explain quantitative variation in nature.
Aínda que o propio Darwin observou que as características endogámicas de razas peculiares de pombas se herdaban de acordo coas leis de Mendel (malia que Darwin non coñecía as leis de Mendel naquel momento), non era obvio que estas características seleccionadas por criadores de razas de pombas puidesen explicar de maneira similar as variacións cuantitativas na natureza.