Other people, though, have used the technique to find more striking results. For example, mammalian bone density usually drops with age. Three years after Kamrin’s work, however, a gerontologist called Clive McCay showed that linking an old rat to a young one boosted the density of the oldster’s bones. In 1972 another paper reported, even more spectacularly, that elderly rats which shared blood with young ones lived four to five months longer than similarly old rats which did not.
The rats themselves, unsurprisingly, were not always keen on the procedure. Early papers describe the dangers of “parabiotic disease”, in which one animal’s immune system rebels against the foreign blood, and also explain how rats must be socialised carefully before being joined, to stop them biting each other to death.
Fascinating. If you can solve the whole "biting each other to death" thing.Read more...