The sperm whale has the heaviest brain on Earth — five times the size of a human’s. Whether that means smarter is harder to say.
How to Play: Guess if the species on the right has a HEAVIER or LIGHTER brain than the one on the left.
Name A
Name B
Top 10 Heaviest Mammal Brains
Brain weight is measured at adulthood. Larger animals have larger brains, but absolute brain size is a poor predictor of intelligence — relative size matters more.
| # | Name | Brain Weight (g) | Unit |
|---|---|---|---|
| 1 | Sperm Whale | 8,000 | g |
| 2 | Killer Whale | 6,800 | g |
| 3 | Blue Whale | 6,800 | g |
| 4 | African Elephant | 5,400 | g |
| 5 | Asian Elephant | 5,000 | g |
| 6 | Pilot Whale | 2,900 | g |
| 7 | Bottlenose Dolphin | 1,500 | g |
| 8 | Human | 1,400 | g |
| 9 | Walrus | 1,100 | g |
| 10 | Horse | 650 | g |
Brain Size and Intelligence
Sperm whale brains weigh 8kg — the largest of any animal. But brain-to-body-mass ratio (encephalization quotient) better correlates with intelligence. Humans have an EQ of 7.5 vs ~0.6 for sperm whales.
Despite small absolute size, dolphins have very high EQs (~5.3) — close to human levels. Their relative brain size compared to body suggests high cognitive ability.
Elephant brains (5.4kg) have many more neurons than human brains (~257B vs 86B), but most are in the cerebellum (motor control), not the cerebral cortex (cognition).
Frequently Asked Questions
Heaviest brain?
Sperm whale at 8kg — the heaviest brain of any living animal.
Are big-brained animals smarter?
Not directly. Brain-to-body ratio matters more. Humans, dolphins, and great apes lead in relative brain size.
Why are dolphin brains complex?
Dolphins have brain folding patterns similar to humans — some researchers suggest their intelligence is comparable to chimpanzees.
Do elephants really have more neurons than humans?
By count yes (~257B vs 86B), but most elephant neurons are in the cerebellum. Humans have more cortical neurons (associated with cognition).
Note: Adult brain weight in grams per veterinary and zoological references.
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