According to science fiction, a bigger brain means superhuman intelligence. It means that you could solve some of the world’s most complex problems in a matter of seconds.
And you could maybe even achieve superhero-like abilities. But would a bigger brain really make you smarter? Why do some experts think that intelligence is based more on your blood flow? And how would our bodies have to evolve to support a bigger brain?
The average human brain weighs about 1300-1400 g (about 3 lbs). If that were to double to 2,700 g (about 6 lbs), that would mean a lot more weight for our bodies to deal with.
Our necks would need to be larger and stronger. Our shoulders would have to be broader to support that extra weight, and as a whole, our bodies would need to be much thicker.
They might not seem like that big of a deal, but these new physical features could cause a lot of problems. For instance, what kind of effects would they have on childbirth?
It might seem a little far-fetched to think of our brains continuously changing in size, but in reality, it’s been happening throughout our entire evolution. Our ancient relatives, Homo habilis, had a brain one third the size of ours. And over the past two million years, it evolved to be the size it is today.
Using this example, you might be thinking, “we are clearly more intelligent than they were, and we have bigger brains, so therefore a bigger brain equals more intelligence.” But that’s not the case. Our brains stopped growing about 20,000 years ago, when we developed stone tools. And we’d like to think we’ve become a bit more intelligent since then.
During the past 20,000 years of human progress and development, our brains have shrunk by 10%. A meta-analysis of over 8,000 brains was conducted in 2015. The researchers found that the size of our brains accounted for only about 6% of the difference in IQ between people.
Researchers from the University of the Witwatersrand in South Africa found that the rate of blood flow to the brain may be a better indicator of intelligence. The rate of blood flow to the brain seems to have increased in all primate lineages over time. But in the hominin lineage — the one that led to us — it increased quicker.
This increase went side by side with the development of tools, the use of fire, and communication within small groups. So if your brain were to double in size, it’s not likely that your intelligence would double along with it. Sorry.
Instead, it would just introduce a lot of problems. As we mentioned, our bodies would become thicker overall to support the greater weight in our heads.
This would be good news for the massage industry, because our necks and shoulders would likely feel sore more often. But it would be bad news for expectant mothers. Not only would each fetus need much higher amounts of nutrients, but vaginal births would also become extremely difficult.
They might become obsolete, and C-sections could become the new normal. And the issues don’t stop there. Because of the extra energy we’d need to support our bigger, heavier brains, people could become less mobile.
And our bodies might grow much slower, and we might not get as tall. So maybe we don’t want a larger brain after all. Who knows if our brains will continue to shrink, or if they’ll start getting bigger again? Whichever direction evolution decides to take us, you can be sure that technology will play a big part in it.
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- “Theories of Intelligence in Psychology”. 2020. Verywell Mind.
- “Why Brain Size Doesn’t Correlate With Intelligence”. 2013. Smithsonian Magazine.
- “We may have got the evolution of our big brains entirely wrong”. Michael Le Page, New Scientist.
- “Do Humans All Have The Same Brain Size?”. 2020. Verywell Mind.
- “How smart were our ancestors? Turns out the answer isn’t in brain size, but blood flow”. 2020. The Conversation.
- “Why do humans grow up so slowly? Blame the brain”. 2014. Science | AAAS.
- “A brief history of the brain”. Robson, David. 2020. New Scientist.