Brain size compared: humans, whales, elephants and crows
A human brain weighs about as much as a bag of sugar. A sperm whale’s is nearly six times heavier. Yet size alone doesn’t explain intelligence — what matters is how many neurons you have and where they sit.
Bigger brain ≠ smarter animal
Large animals need large brains simply to run large bodies: more skin to feel, more muscle to control. That is why scientists compare the encephalization quotient — brain size relative to what is expected for the body size. Humans score about 7, dolphins about 4–5, chimpanzees about 2.5, and a typical cat about 1.
It’s the neurons that count
Counting neurons became possible only recently, with a technique that dissolves brain tissue into a “soup” of cell nuclei. It showed the human brain holds about 86 billion neurons, around 16 billion of them in the cerebral cortex — the most of any animal. An African elephant has even more neurons in total (about 257 billion), but 98% sit in its cerebellum, which controls its enormous body and trunk; its cortex has only about 5.6 billion.
An expensive organ
Your brain is about 2% of your body weight but burns roughly 20% of your resting energy — around 20 watts, less than a light bulb. Cooking food, which releases more calories, may be one reason our ancestors could afford such a hungry brain.
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