Back in 2005, Irena M. Conboy and colleagues published a paper in Nature detailing a heterochronic parabiosis experiment, that investigated aging in mice. They were investigating whether the blood coursing through the arteries and veins of old animals differed from the blood that kept young animals alive. To perform the experiment, they surgically connected the circulatory system of an old mouse to that of a young one. This caused the blood sustaining the old mouse to be 50% old and 50% young. Continue reading →