The first genetically engineered products eaten by humans were cheese and tomatoes. Stanley N. Cohen and Herbert Boyer demonstrated the creation of first functional GMO in 1973 that combined and replicated genetic information from different species. Genetically Modified (GM) bacteria were first used to produce an alternative enzyme, chymosin, to calf rennet, so as to make vegetarian cheese. The first transgenic animals were mice created by Rudolf Jaenisch at Ohio University in 1974. Jaenisch successfully inserted foreign DNA into the early-stage mouse embryos; the resulting mice carried the modified gene in all their tissues. The first transgenic plant was produced in 1983, when a tobacco line expressing kanamycin resistance was produced. "Flavr Savr? tomato was the first transgenic variety to reach the market; fruits of this variety remain fresh for a prolonged period as their softening gene was ?switched-off?, allowing them to ripen on the vine until they reach full flavor and color without rotting.