Giants once roamed the earth. Oceans teemed with ninety-foot-long whales. Huge land animals–like truck-sized sloths and ten-ton mammoths–ate vast quantities of food, and, yes, deposited vast quantities of poop.
A new study shows that these whales and outsized land mammals–as well as seabirds and migrating fish–played a vital role in keeping the planet fertile by transporting nutrients from ocean depths and spreading them across seas, up rivers, and deep inland, even to mountaintops.
However, massive declines and extinctions of many of these animals has deeply damaged this planetary nutrient recycling system, a team of scientists reported October 26 in theProceedings of the National Academy of Sciences.