The human brain is sometimes called the "most complex thing in the universe”. It allows us to study ourselves, other animals, and the cosmos itself. Indeed, we often think of our brain as the pinnacle of animal evolution.

But what do we actually know about the human brain? How different is it from the brain of an elephant? A chimpanzee? A raccoon? And if our brain is not the biggest in the animal kingdom (it is not), then what, if anything, makes it worth the hype?

To discuss this topic, I am joined by the Brazilian neuroscientist Suzana Herculano-Houzel. An associate professor at Vanderbilt University, Herculano-Houzel has done more than perhaps any living human to help us understand these questions. And her work has a wonderful capacity to explain why the human brain is so remarkable, but simultaneously, why it still fits within the broader patterns we see in other animals. (That’s unlike the elephant, the raccoon, or the chimpanzee. Their brains are truly special, she says.)

Herculano-Houzel’s work also suggests an answer to one of the biggest question in human evolution: If a big brain is a good idea, why didn’t all other animals grow one?

As always, the conversation finishes with my guest's reflections on humanity.

Thank you, as always, for listening!

(You can also keep scrolling down to find some useful bits, such as useful links and lists of terms, names, and numbers mentioned in the episode conversation. Or do you prefer reading to listening? Or wish to get back to some highlights? From the 5th of October onwards, you can also read a breakdown of this conversation on Substack⁠.)

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MENTIONS

Technical terms

The (cerebral) cortex / The cerebellum / Neurons / Stereology / The grandmother hypothesis (see episode 6)  

Names

Harry Jerison

Numbers

Neurons in the whole brain of humans (86 billion) and elephants (257 billion)

Neurons in the cerebral cortex of humans (16 billion), great apes (6-8 billion), elephants (5-6 billion), dolphins & whales (1-4 billion, based on estimations), baboons (2- 3 billion), t-rex (2-3 billion based on estimates), smaller monkeys (1-3 billion), raccoons (over 1 billion), crows (a notch less than 1 billion)

Links

T-rex video: ⁠https://www.youtube.com/watch?v=a1tEnm53zDs⁠

Herculano-Houzel’s TED talk (viewed almost 4 million times): ⁠https://www.ted.com/talks/suzana_herculano_houzel_what_is_so_special_about_the_human_brain?language=en⁠

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