Because of its high biodiversity Mexico has also been a frequent site of bioprospecting by international research bodies. The first highly successful instance being the discovery in 1947 of the tuber "Barbasco" (''Dioscorea composita'') which has a high content of diosgenin, revolutionizing the production of synthetic hormones in the 1950s and 1960s and eventually leading to the invention of combined oral contraceptive pills.