WASHINGTON (AP) - Scientists calculate that when you weigh all life on Earth, billions of humans don't amount to much compared to trees, earthworms or even viruses. But they say we really know how to throw around what little weight we have.
A first-of-its-kind global biomass census found that humans only add up to about one ten-thousandth of the life on Earth. The planet's real heavyweights are plants. They outweigh people by about 7,500 to 1, and make up more than 80 percent of the world's biomass, the study said.
Since civilization started, humans helped cut the total weight of plants by half and wild mammals by 85 percent. Now domesticated cattle and pigs outweigh wild mammals 14 to 1.
The study is published in Monday's Proceedings of the National Academy of Sciences.