So it goes with the animal-spillover theory. The evidence in favor has always been highly esoteric, knotted with data and interpretation. Scientific points are made—a particular run of viral nucleotides is a “smoking gun” for genetic engineering, one famous scholar said in 2021—and then they are re-argued and occasionally walked back. Long-hidden sample data from the market suddenly appear, and their meaning is subjected to vituperative, technical debate. If the evidence for a lab leak tends to come from messy human stuff, the evidence for animal spillover emerges from messy data. Simple-seeming claims are draped across a sprawl of numbers.