Observed Evolution

We don't have to infer evolution only from the past — we can watch it. Bacteria evolve antibiotic resistance in hospitals within years; the peppered moth shifted from pale to dark and back as industrial soot came and went.^[3] The cleanest demonstration is Richard Lenski's E. coli experiment: twelve populations grown for 75,000+ generations and counting, with frozen samples as a living fossil record. They steadily grew fitter, and one lineage evolved a brand-new ability — feeding on citrate — before the researchers' eyes.^[1] This is natural selection caught in the act.^[2]