> Men who had given blood more than 100 times in their life were more likely to have blood cells carrying certain beneficial mutations, suggesting that donating blood promotes the growth of these cells.
Or maybe it's just bleeding more than 100 times, it seems unlikely that the body knows it's delivering to a needle instead of somewhere else. So bring on the leeches.
> Men who had given blood more than 100 times in their life were more likely to have blood cells carrying certain beneficial mutations, suggesting that donating blood promotes the growth of these cells.
Or maybe it's just bleeding more than 100 times, it seems unlikely that the body knows it's delivering to a needle instead of somewhere else. So bring on the leeches.
Or, it’s a classic correlation != causation.