https://www.newscientist.com/article/2112829-blood-from-human-teens-rejuvenates-body-and-brains-of-old-mice/
The key to youth appears to be in the blood plasma – the liquid part of blood. Several studies have found that injecting plasma from young mice into old mice can help rejuvenate the brain and other organs, including the liver, heart, and muscle.
Blood has the power to turn back time. So vampirism is not at all a lie.
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German article in "fringe science"
http://www.grenzwissenschaft-aktuell.de/mythos-junges-blut-verjuengt20161124/
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Is then "blood" in a complete other sense as we learned the "seat of life"? Is it a lifebearer and lifegiver itself? But would blood then not be a lifegiver like God was, his concurrent and the secret source or key to eternal life? A key to eternal life that mankind should lately discover in itself, lifeforce in the body? A divine present that is in our midst and that is placed in our body and should be once discoverd? It sound utopian like a similiar story about the stemcell-therapy story or the story about nearly eternal living creatures like medusa etc. that circled around some time ago.
But in the case of blood transfusion, that would be interesting, if we would transfuse the "life" of another person into our body in this new sense, wouldnt we somehow share our "lifeforce"? Before developping further this new thought we should ask the realists how much substance these "scientific" articles have.
Perhaps we make a list with all potential animals with eternal life already discovered.
Cofty has certainly an answer.