A scientist, W. Donner Denckla, at the National Institute of Alcoholism and Alcohol Abuse, removed the pituitary glands of rats and injected the necessary hormones for survival. These rats lived much longer and showed fewer signs of aging than ordinary rats. At 24 months of age, only two out of 125 control rats were still alive. This is a typical lifespan for rats. Of the 95 rats without the pituitaries, even though handicapped, at age 34 months, 20 were still alive. This is equivalent to humans at age 95, where only one percent of us are still alive.