Total Weight of Wild Land Mammals Less Than One-Tenth Weight of All Humans

Elephants in Tanzania's Serengeti National Park.

Elephants in Tanzania's Serengeti National Park. Eric Dietrich / U.S. Navy

The combined weight of every human is more than 10 times that of every wild land mammal put together, a new study finds.

“When you look at wildlife documentaries on television — for instance of wildebeest migrating — it is easy to conclude that wild mammals are doing quite well,” Ron Milo, a biologist at the Weizmann Institute of Science and coauthor of the study, told The Observer. “But that intuition is wrong. These creatures are not doing well at all.”

Every elephant, bear, bison, gazelle, and other land mammal put together weigh around 22 million metric tons, the study shows, while wild marine mammals, such as dolphins and whales, weigh some 40 million tons in total.

Itai Raveh / Weizmann Institute of Science

Humans, by contrast, weigh 390 million metric tons, while domesticated mammals — from sheep and cows to dogs to city-dwelling rats — weigh around 630 million metric tons combined. The findings were published in the Proceedings of the National Academy of Sciences.

The staggering imbalance highlights the profound ways that humans have reshaped life on Earth, researchers say. House cats are nearly twice as massive as African elephants, while pigs are double the weight of all wild land mammals put together. All told, wild mammals account for just 6 percent of all mammals by weight, with humans and domesticated mammals accounting for the rest.

“This study is an attempt to see the bigger picture,” Milo said in a statement. “It lays bare the dominance of humanity and its livestock over the far smaller populations of remaining wild mammals.”


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