the MacCready Explosion occurred in only about 10,000 years, or 500 human generations. According to MacCready’s calculations (1999), at the dawn of human agriculture 10,000 years ago, the worldwide human population plus their livestock and pets was only ~0.1% of the terrestrial vertebrate biomass. (We’re leaving out insects, other invertebrates, and all marine animals.) Today, by his estimation, it is 98%! (Most of that is cattle.)
