While DNA as the carrier of genetic information was not confirmed until 1944, research on the inheritance of traits had been taking place long before this. Key work was done by Gregor Mendel, a Moravian monk, who performed extensive experiments on pea plants, publishing his findings in 1866. Mendel followed certain binary traits through multiple cultivated generations, collected quantitative data, and subjected the data to statistical analysis. The analysis revealed that, for the traits Mendel examined, one form (allele) of the genetic factor (gene) is dominant, and one is recessive; each gamete contains only one allele of a gene; and alleles for separate traits are passed independently of each other. A gamete is a haploid cell that contains half the genetic material of a complete organism and can fuse with another gamete to form a zygote. Characteristics controlled by a single gene that has one dominant and one recessive allele are called Mendelian traits. Simple Mendelian inheritance patterns are relatively rare in nature and many of the Mendelian traits in humans cause disorders such as sickle cell anemia.