The expression "epigenetic landscape" was coined by British developmental biologist Conrad Hal Waddington (1905-1975). He compared gene regulation during development to marbles rolling downhill towards a wall. As cells differentiate, the different cell fates are represented by the lowest points in a landscape made of several pits, some lower than others. Waddington also coined the expression "canalization" to describe the ability of organisms to produce the same phenotype against genetic and environmental variations.