<p>I came across this <a href="https://www.scientificamerican.com/article/why-does-the-brain-need-s/" rel="noreferrer">article</a> which states that brain takes about 20% of the body's energy. This is quite a lot compared to its size. Somewhere I read that even if this is a lot, this must be an absolute requirement otherwise by the theory of evolution, such high energy requirement brains would already have been eliminated.</p>

<p>My question is we know evolution is never stationary, so what is the recent trend (last 4000-5000 years) in the usage of brain energy? To me only 2 cases are possible (in an evolutionary stable sense):</p>

<ul>
<li>We are evolving to require less brain power for the same functionality, but the size of functionality remains same (i.e. we are able to think the same thing with same power requirement).</li>
<li>We are evolving to require more brain power for the same functionality, but the size of functionalities increase(i.e. we are now able to think the bigger things but the power requirement increases).</li>
</ul>

<p>I might be wrong in the above 2 statements or it may seem redundant, but I am drawing parallels to IC's here in a broader sense.</p>

<p>Also can these generalisations be extended to the evolution of animal brain also?</p>

<p>Any kind of speculative answer based on logic would also be nice.</p>

CC BY-SA 4.0
2018-08-31T18:06:29.000Z
This question may be answerable from the context of evolution of modern humans vs earlier humans, or in the context of evolution from common ape ancestors, but how exactly do you expect to measure brain energy use from someone 4000 years ago?
Bryan Krause
CC BY-SA 4.0
2018-08-31T18:20:09.493Z
@BryanKrause I don't know maybe modern technology could do it? I have no idea
DuttaA
CC BY-SA 4.0
2018-09-01T04:56:27.257Z
@BryanKrause on second thoughts it seems that their really is no way of measuring brain activity in ancient times but can we not measure from atleast 10000 years back from genetic data
DuttaA
CC BY-SA 4.0
2019-04-05T14:25:01.023Z
Could intracranial space provide a basis to measure energy consumption?
youzer
CC BY-SA 4.0
2019-04-05T18:49:26.727Z
@youzer I'm not actually a neuroscientist...Just an amateur with some interest (I know about brain structure and working of neurons to some amount of detail that's all), so I guess you have to answer that keeping in mind.
DuttaA
CC BY-SA 4.0
2022-11-30T05:10:35.840Z
There was a widely publicized paper suggesting that [human brains shrank](https://doi.org/10.3389/fevo.2021.742639) around 3000 years ago, presumably as a result of outsourcing brain functions to society and technology, but this finding has been [challenged since as invalid](https://doi.org/10.3389/fevo.2022.963568).
Arnon Weinberg
<evolution><brain><brain-development>
How is the human brain evolving?
DuttaA
# How is the human brain evolving?

(Asked by: username_0 on 2018-08-29)

I came across this [article](https://www.scientificamerican.com/article/why-does-the-brain-need-s/) which states that brain takes about 20% of the body's energy. This is quite a lot compared to its size. Somewhere I read that even if this is a lot, this must be an absolute requirement otherwise by the theory of evolution, such high energy requirement brains would already have been eliminated.

My question is we know evolution is never stationary, so what is the recent trend (last 4000-5000 years) in the usage of brain energy? To me only 2 cases are possible (in an evolutionary stable sense):

* We are evolving to require less brain power for the same functionality, but the size of functionality remains same (i.e. we are able to think the same thing with same power requirement).
* We are evolving to require more brain power for the same functionality, but the size of functionalities increase(i.e. we are now able to think the bigger things but the power requirement increases).

I might be wrong in the above 2 statements or it may seem redundant, but I am drawing parallels to IC's here in a broader sense.

Also can these generalisations be extended to the evolution of animal brain also?

Any kind of speculative answer based on logic would also be nice.

**Tags:** evolution, brain, brain-development

> **Comments:**
> **username_1**: This question may be answerable from the context of evolution of modern humans vs earlier humans, or in the context of evolution from common ape ancestors, but how exactly do you expect to measure brain energy use from someone 4000 years ago?  
> **username_0**: @BryanKrause I don't know maybe modern technology could do it? I have no idea  
> **username_0**: @BryanKrause on second thoughts it seems that their really is no way of measuring brain activity in ancient times but can we not measure from atleast 10000 years back from genetic data  
> **username_2**: Could intracranial space provide a basis to measure energy consumption?  
> **username_0**: @username_2 I'm not actually a neuroscientist...Just an amateur with some interest (I know about brain structure and working of neurons to some amount of detail that's all), so I guess you have to answer that keeping in mind.  
> **username_3**: There was a widely publicized paper suggesting that [human brains shrank](https://doi.org/10.3389/fevo.2021.742639) around 3000 years ago, presumably as a result of outsourcing brain functions to society and technology, but this finding has been [challenged since as invalid](https://doi.org/10.3389/fevo.2022.963568).  

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## 0 answers

