Humans weigh 350 times as much as all the world’s bison and elephants combined, and more than 10 times as much as all the world’s wild mammals. Combined with all domesticated animals, humans account for more than 97% of the mass of land mammals. Twenty centuries earlier, at the birth of Christ, the entire human race weighed only two-thirds of all the bison in North America, and less than one-eighth of all the elephants in Africa.
