We (multi-cellular life with long generation times) are large bags of nutrients and useful energy. Once we die those nutrients are quickly recaptured by a whole swarm of microbiota; I'll spare you the details of human decomposition but the plant version [is fascinating](https://www.nature.com/articles/s41598-021-88580-2). Since we seem to be so delicious... how are we able to keep the microbial world at bay _before_ death? It's not the immune system; the immunocompromised among us are not decomposing any faster than we are. But even if it _was_ the immune system: we have natural defenses and those may pose a bit of a barrier but evolution is a decent problem solver. The generation time of most human pathogens is, generally, <10 hours. Over an 80-year lifespan that's >70k generations. Our watchmaker is just as blind as theirs. Imagine playing chess with someone just as smart as you who has 70,000x the time to think. Evolution is slow but it's not _glacial_, shouldn't we be dead? Consider antibiotics, the history of nearly every antibiotic sketches out the same narrative arc: It is discovered, widely deployed, then [stops working](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4378521/)[^1]. Here's a quote: > This drive toward multidrug resistance is not new and is a direct consequence of antibiotic use. Because of the large numbers of microbial genomes (it is estimated that there are $10^{30}$ bacteria and their genomes on the planet) the potent, selective pressure of antibiotics means that resistance, if compatible with the organism’s physiology, is almost inevitable. - [source](https://www.science.org/doi/10.1126/scitranslmed.abo7793) So, take that last sentence and replace "antibiotics" with "the immune system", shouldn't it still be true? [Pando](https://en.wikipedia.org/wiki/Pando_(tree)) presents an even more difficult case-study, it's a forest where each tree is a clone of an original tree which lived [up to 9000](https://www.sciencedirect.com/science/article/abs/pii/S0378112722004303) years ago. This forest is running 9000 year-old code, with an immune system not nearly as fancy as ours. In those 9000 years, the 10-hour-generation-time potential pathogens surrounding this tree have had something like 8M generations to figure out how to get inside. Evolution can do amazing things given that much time, 8M of _our_ generations ago we were hiding from dinosaurs and still a couple million generations away from becoming primates. [^1]: [This](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5369031/#s5title) read is also quite sobering