 The brain is the largest known of any modern or extinct animal , weighing on average about 7 @.@ 8 kilograms ( 17 lb ) , more than five times heavier than a human 's , and has a volume of about 8 @,@ 000 cm3 . Although larger brains generally correlate with higher intelligence , it is not the only factor . Elephants and dolphins also have larger brains than humans . The sperm whale has a lower encephalization quotient than many other whale and dolphin species , lower than that of non @-@ human anthropoid apes , and much lower than humans ' . 
