The award for the largest brain in the world goes to…

The adult human brain weighs about 3 lbs, which is an incredible feat in it itself, as it is only supported by 7 vertebrae. But we really do not even come close to the biggest brain. One might think it belongs to the blue whale, as it is the largest animal on earth. One would be wrong! In fact, the largest brain on earth weighs approximately 20 lbs! “Big Brain” has been synonymous with the overtly smart in pop culture. But does size matter? In this post, we will dissect who in fact wields this bulbous brain and if it in fact makes them the smartest in the world.

Let’s compare sizes

The largest brain in the world belongs to the sperm whale! Now having a big brain doesn’t necessarily mean its brain is more powerful. The cerebellum is responsible for sensory information, motor actions, and cognition. In a study by Muller and Montgomery in 2019, they found evidence that the cerebrum and cerebellum (two large regions of the brain) are particularly big in cetaceans. They think it is due to an adaptation to their environment.

But not all cetacean brains are equal. The killer whale’s cerebellum is 14% of the total brain mass while the sperm whale’s is only 7%. This might mean that, though sperm whales have big brains, they are not necessarily the smartest whale! Ridgeway and Hanson, who reported that the cerebellum is larger in killer whales than in sperm whales, suggested this could be due to the killer whale needing a more active vision, a wider range of phonation, or a wider prey range than the sperm whale. We attempted to recap the functions of the cerebellum below.

Still smart enough to escape whalers!

Sperm whales may have a smaller cerebellum than killer whales, but they are still incredibly smart. They used to be one of the whalers’ targets during the whaling era in the 19th century. At the very beginning, they were an easy and lucrative catch, until they weren’t… Researchers and hunters both began to see how, almost immediately, this species started to evade the hunters, dropping success rates by 60%. The hypothesis was that they were communicating with each other to help better avoid the whalers. We have seen a few species of cetaceans communicate, recognize themselves, and are capable of complex problem-solving. No specific studies haven’t been conducted on our big-brained friend, but a lot has been done with its dolphin cousins! If you wish to read more about dolphin intelligence, click here.

The conclusion?

More research needs to be done in other to find out who is the smartest mammal, even though the sperm whale has the biggest brain. The brain is a very complex and cool thing. There is so much to still learn, especially for our underwater friends!

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Thanks for reading! Comment below what are your thoughts on this big-brained whale! Find out more below:

• Encyclopedia of Marine Mammals (3rd Edition)
• Muller, A. S., & Montgomery, S. H. (2019). Co‐evolution of cerebral and cerebellar expansion in cetaceans. Journal of evolutionary biology, 32(12), 1418-1431.
• Hanson, S. H. R. A. C. (2014). Sperm Whales and Killer Whales with the Largest Brains of All Toothed Whales Show Extreme Differences in Cerebellum.

What do we know about intelligence in whales and dolphins?