Our Brains Shouldn’t Be So Big

It's no secret that humans have big brains, especially compared to the rest of the animal world. But big brains require big energy to power them, and shifting around all our calories to fuel our massive brains was no small feat. From the Taung Child to modern biometrics, here's how we can learn all about what it took to make our species such egg-heads.

Hosted by: Niba @NotesbyNiba (she/her)

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[Fayanora]

On the issue of digestion: cooking helps a lot there, too. A lot of cooking is basically just pre-digesting foods in one way or another, making the food a lot easier to digest and making it digest faster. Making things easier to chew, or removing the need to chew entirely, also speed up the process and use less energy.

[RobinDSaunders]

As well as eating more meat, by close to a million years ago our ancestors were using fire to cook their food. This greatly increases the nutrition available from food while reducing the effort needed for digesting it. Control of fire, and cooking in particular, are now seen as crucial to the later parts of human evolution.

[FrozEnbyWolf-bt]

I feel compelled to point out, it's not about the sheer number of neurons in the brain, but about the connectivity between them. Intelligence in the broad sense of the term is determined by the number of connections and how well they're maintained.

[gracelovely]

I love when we study humans like we do any other animals. Our cognitive function as a species is impressive lol

[qwertyuiopst]

Our ancestors stumbled into a feedback loop where increased mental abilities resulted in increased opportunities for increased mental abilities - and, because it was relatively simple approach for evolution to accidentally use, a lot of that increased mental abilities involved having a larger brain. But we've mostly reached the practical maximum size, so the evolutionary path that remains open is improved organization/flexibility of the brain - which provides room for brain size to be reduced because of the constant pressure for using less energy.

[NedskiYT]

"Here I am, brain the size of a planet, and they ask me to take you up to the bridge. Call that job satisfaction? 'Cause I don't."
Said Marvin the Robot. 🤖

[nonya-bizness]

I had heard another reacent study had suggested that what's important for intelligence is not only not about brain size, but also not about brain size to body size ratio either. instead what was suggested is that what is more important is brain density, such as in some certain kind of crow that has a much lower brain size to body size ration when compared both to humans AND other types of crows, but has a denser brain than that of the other crows and a closer to human level intelligence.

so if our brains are actually shrinking in volume, perhaps they are simply getting a bit denser.

[juliazollinger]

4 ping pong balls. What a random unit.

[TheSeventhChild]

2:25 If you have captions on you can see where they wrote the script and then realized they needed to reword it but didn't catch it for the captions.

[lunabornegnr]

Niba is a lovely host! Would love to see her more!

[xentrix]

According to an older SciShow video (Why Our Brains Love Junk Food), cooking is an important factor too, since it allowed the intake of much more energy.

[melissatrible]

One hypothesis I've heard (it was years ago, so I'm not sure how it is generally viewed now) is that, at a certain point, *we* became our own competitive environment. That is, at a certain point, it was less a matter of us getting bigger brains in order to extract more resources from our environment, and more a matter of us being able to get or keep resources (and mates and so on) from our fellow humans. Call it the keeping up with the Joneses hypothesis.

Basically, the idea is that at a certain point, our brains were...basically as big as they were ever going to need to be for sheer extraction of calories and other necessary materials from the actual environment. At a certain point, being smarter than your prey or whatever only does so much to help you, and in a strictly utilitarian sense you're better putting those extra "points" into, like, longer legs or better fat storage or something.

But, once you got those calories home to the tribe, bigger brains could keep you from getting tricked out of those calories by another tribe member, or let you impress a potential mate, or even let you be the one tricking other people out of their calories, or trading those calories someone else brought home for some less risky thing (eg tool making) that you were good at. So the ones who kept putting those extra "points" into big brains kept having more surviving babies (one way or another), and we kept getting, as a species, bigger and bigger brains.

[JulJulJulJulJulJul]

Whenever you feel dumb, just remember that all of us are bigbrains. Even you!

[tatotato]

I like her voice, very easy to listen to

[johnabbe]

Around 8:45, during talk about Out of Africa I (2 million years ago) you showed a graphic for Out of Africa II (200, 000 years ago or less), which was then very confusing when the following audio was about what happened 800, 000 years ago.

[islandsedition]

1:45 i cant help think that the body:brain ratio is a bit of a red herring. Body mass and shape is very much related to the environmental pressures/advantages, whereas a better ratio would be Brain:things it needs to control. Probably, most mammals have about the same number of things run by the brain given they have roughly the same number and type of organs and limbs etc.

[Not_daniel_here]

4:51 analogy doesn't quite work when eggs were around YEARS before chickens ever were 😅

[sideb]

sorry to comment about appearances on a scientific discussion, but i really like Niba's outfits!
i really appreciate doing something visually different and creative in a stem space usually filled with just a bunch of t-shirts and jeans:))
i really enjoy wondering about the different colors combinations and designs while listening to the explanations..
and the purple scarf-cape-wings are really cool! i want some too lol

[MasterOfTheSacredArts]

I feel like my brain's 40 times smaller tbh

[jamiekirkland]

Also in pulp fiction, Samuel L Jackson also asked "Why am I on brain detail?"