Enric Sala

, 96 percent of the mass of mammals on the land is us and our domesticated livestock. Only 4 percent is everything else, from elephants to bison to panda bears. As a matter of fact, we have lost 60 percent of the terrestrial wildlife since 1970 and 90 percent of the large fish in the ocean (sharks, tuna, cod) in the last century. Seventy percent of the birds on Earth are our domesticated poultry—mostly chickens—and only 30 percent are wild.