One of biology’s wilder facts is that we’re all family. You and me, sure, but also me and a mushroom. Triceratops shared genes with you. So does the virus that makes you cough, and a rosebush. Bacteria left us on the tree of life around 2.7 billion years ago, but the wet world they came from is still ours: One code runs all of life. The same proteins that imprint memories in your neurons, for example, do so in octopi, ravens, and sea slugs. This genetic conservation means tricks from one species can be hijacked. If you stick a jellyfish gene in a monkey, it’ll glow green.