When Gregor Mendel crossed purebred tall pea plants with purebred short pea plants, the offspring (F1 generation) were all tall. The short allele was present, but it was masked. Mendel referred to this as the law of dominance. Mendel stated that an allele is dominant if it can mask (dominate) a contrasting allele. The allele that is masked is known as a recessive form of the gene. It is important to note that a dominant allele is no better, stronger, or more advantageous than a recessive allele. Dominant simply refers to the allele's ability to mask a contrasting allele. For example, there is no genetic advantage to having a brown-eye allele or a blue-eye allele. Further, dominant alleles are not always the most abundant in a population. For instance, people that have extra fingers or toes inherited a dominant allele for a condition known as polydactyly. Even though the allele for this condition is dominant, the trait is comparatively rare in the human population.