b'In the early 2000s, a handful of young scientists at Stanford turned the university\\u2019s Palo Alto campus into the mouse-stitching-together capital of the world. Reviving a centuries-old procedure known as parabiosis, they connected the circulatory systems of dozens of pairs of rodents, young sutured to old, so that they\\u2019d pump one another\\u2019s blood back and forth.\\nLearn more about your ad choices. Visit podcastchoices.com/adchoices'