As humans, we're proud of our big brains. But our brains aren't nearly the biggest on earth. That distinction belongs to the sperm whale, whose brain on average weighs 17 pounds, about four times as much as a human's. Elephants also have large brains that weigh on average 11 pounds. However, these animals are huge — what happens if one takes into account brain size relative to body size?Read more about what giant brains do for dolphins and elephants ar Brain Decoder: How Do The Huge Brains of Dolphins and Elephants Compare To Yours?