Hello, my name is Ron White. I am a two-time USA Memory Champion, memory training expert and memory keynote. I find the brain fascinating, and enjoy learning more about it. I would like to share this bit of information with you.
Scientists cannot come together as to what makes human beings more intelligent than other creatures walking the earth, but they generally agree that they are. There are a lot of animal species that can do some of the same things we do – problem solving, show emotions, learn to use tools and show self-awareness. Think of the other intelligent animals, like the pig, dolphins, dogs, chimpanzees.
Intelligence also has to do with the different makeup of the brain. For the most part, the most intelligent animal are mammals, which have very large cerebral cortexes. The cerebral hemispheres are housed in the cerebellum, the areas of the brain that are responsible for higher functioning – such as communication, memory, learning and thought processes. We humans have the largest cerebral cortex of all mammals, relative to the size of their brains. If we are then, is our brain bigger than other animals as well?
The average adult human brain weighs about 3 pounds. So does the dolphin, a very intelligent animal. On the other hand, the sperm whale, not considered to be as intelligent as the dolphin, has a brain that weighs about 17 pounds. A beagle’s brain is about 2.5 ounces, and an orangutan brain is approximately 13 ounces. They both have fairly small brains, yet are considered pretty smart. Birds, like a sparrow, have a brain that weighs less than half an ounce. 
The larger the body, the larger the skull, and for the most part the larger the brain. The dolphin weights around 350 pounds. The sperm whale’s weight is around 13 tons. Beagles are small to medium sized dogs, so their brain will be smaller.
Relationships between brain size and intelligences has no direct bearing on the actual weight of the brain – which is in relation to the entire body weight of the animal. Humans have a brain to body mass ratio (Encephalization Quotient – EQ) of 1-to-50, so if you are a small person (approximately 100 pounds) you would typically have a 3 pound brain or EQ of 3%. Most other mammals body to brain ration is 1-to-180. For birds the ratio is 1-to-220. This shows that the brain in a human takes up more of the body than that of other animals, followed by the dolphin.
There is an exception – certain species of shrews have the highest EQ of all – at about 10% of their body weight is brain. So, who is smarter – you or a shrew?
Sources:
Discovery, Fit & Health – The Human Brain is the Biggest Brain: http://health.howstuffworks.com/human-body/systems/nervous-system/10-brain-myths5.htm