When comparing the human brain to the brain of an elephant or whale, it is important to take into consideration the concept of "brain-to-body ratio." The brain-to-body ratio refers to the proportion of brain size relative to the overall body size of an organism. This ratio is significant because it provides insights into the relative importance of the brain in the functioning of different species. While the human brain weighs approximately three pounds, the brain-to-body ratio in humans is relatively high compared to many other animals, indicating the importance of our brains in cognitive and intellectual functions. In contrast, some large mammals like elephants and whales have much larger brains than humans due to their overall size, but their brain-to-body ratio may be lower, signifying different evolutionary adaptations and behaviors.