How Well Does Body Weight Explain Brain Weight For Mammals?

A blue whale weighs around sixty tons and its brain weighs six kilograms, a human being on the other hand has an average body weight of seventy kilograms and a brain that weighs a kilo and three hundred grams. In terms of proportion the brain of a human is nearly two per cent of its body weight where as that of a blue whale is less than .01 per cent. As a general rule the larger an animal becomes the less its brain size gets in proportion to its body mass. Also the larger the size of the brain as compared to the body's weight the more intelligent the species is believed to be. This is generally irrespective of weather the species is a mammal or not.