<p>Hemispherectomy is a surgical procedure employed to treat epilepsy where an entire hemisphere of the cortex is removed. Astonishingly, when it is performed on very young children, they are seemingly able to live out perfectly normal and even successful lives, and, in some cases where the recovery was particularly extensive, even get degrees in fields that seem like they require a lot of brain power to work in. The remaining hemisphere is plastic enough to recover some functions of the missing one.</p>
<p>My question is this: if this is possible, then why in the world aren't our brains way smaller? Why did lateralization evolve as a clever trick to fit more functions in a skull already almost too big to safely birth, if all the functions of the cortex could already have fit in half the volume?</p>
<p>Has anyone ever proposed a hypothesis on this matter?</p>

CC BY-SA 4.0
2023-12-21T13:12:46.737Z
Welcome. A truly fascinating branch of research isn't it? Having said that, have you scoured the internet for side effects of hemispherectomy? For one thing, vision is lateralized such that one hemisphere of the visual field is covered by one hemisphere in the brain.
AliceD
CC BY-SA 4.0
2023-12-21T18:17:39.813Z
We live in a great world, where people with massive disabilities, such as missing limbs, paralysis, sensory deficits, mental dysfunctions, and debilitating diseases, can live prosperous, even successful lives. That is not the world that we evolved in however, where such disabilities would have been deadly - do not mistake success in this world for success in our ancestral one.
Arnon Weinberg
<neuroscience><brain>
What is the point of having two hemispheres if one works just as well?
Enrico
# What is the point of having two hemispheres if one works just as well?

(Asked by: username_0 on 2023-12-21)

Hemispherectomy is a surgical procedure employed to treat epilepsy where an entire hemisphere of the cortex is removed. Astonishingly, when it is performed on very young children, they are seemingly able to live out perfectly normal and even successful lives, and, in some cases where the recovery was particularly extensive, even get degrees in fields that seem like they require a lot of brain power to work in. The remaining hemisphere is plastic enough to recover some functions of the missing one.

My question is this: if this is possible, then why in the world aren't our brains way smaller? Why did lateralization evolve as a clever trick to fit more functions in a skull already almost too big to safely birth, if all the functions of the cortex could already have fit in half the volume?

Has anyone ever proposed a hypothesis on this matter?

**Tags:** neuroscience, brain

> **Comments:**
> **username_1**: Welcome. A truly fascinating branch of research isn't it? Having said that, have you scoured the internet for side effects of hemispherectomy? For one thing, vision is lateralized such that one hemisphere of the visual field is covered by one hemisphere in the brain.  
> **username_2**: We live in a great world, where people with massive disabilities, such as missing limbs, paralysis, sensory deficits, mental dysfunctions, and debilitating diseases, can live prosperous, even successful lives. That is not the world that we evolved in however, where such disabilities would have been deadly - do not mistake success in this world for success in our ancestral one.  

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## 0 answers

