A first-of-its-kind study reveals that humans make up a minuscule portion of life on the planet. As in 0.01%, reports the Guardian. The flip side of that? Despite the scant figure, humans have reshaped the animal kingdom, helping wipe out about 83% of mammals and half of all plants since civilization began, according to the comprehensive survey in the Proceedings of the National Academy of Sciences. For this study, researchers weren't counting individual members of species. This is all about weight—they surveyed the Earth's biomass, meaning the carbon content in living creatures. Start with this: All life on the planet weighs about 550 gigatons, notes Science. The new study breaks down that figure, including these highlights: