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Comment by tlarkworthy | Hacker News Reader

This article does not really debunk anything as it seem to use some very poor chains of reasoning:

"If we are using only 10% of our brains, that means a person would be fine if the other 90% of the brain got removed. 10% of the 1400g average brain is 140g—that’s the size of a sheep’s brain.4 Since I doubt sheep have their own 90% hidden potential myth, it makes no sense that humans have advanced so far as a civilization by using only part of their brains equivalent in size to a sheep’s brain."

1. That using 10% of brain means 90% can be removed. Where did that logic come from?

2. That size of the brain is important (i.e. the size of a sheep brain is relevant to human intelligence, this is a poor argument as an elephants brain is much larger than a human's)

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There are 2 sides to this. On one hand people have undergone total or subtotal hemispherectomies with minimal to no changes to their cognitive function, or other personality aspects. On the other hand this doesn't imply that you can remove anything "up to" 50%. Some bits are "make or break".

To make a CPU analogy, plenty of CPUs can (are designed to) function just fine with disabled cores. But certain units cannot be disabled and still have a functional CPU. The IMC or chip interconnect may take little die space but would leave the CPU dead in the water if removed.

Not all parts of the brain are created equal, not 100% of the brain is there for us to "use" (as in we're not consciously using them, they provide autonomous "built-in" functions), and the parts that we consciously make use of might very well be underused. Few people would ever need to use at once all parts of the brain for all possible processing needs like all types of sensorial input processing, all types of memory memory, all types or reasoning, empathy, multitasking, etc. So they'll use a few at a time. Maybe 10%.

There probably is a significant base load and I don't think we can measure neuronal activity as well as we like to pretend. Imagine being consciously as good in trigonometry as your eye-brain...

I believe size has an effect, elephants are pretty smart, and there is a general trend in the animal kingdom that would confirm this. Structural density is important too as well as type of brain matter. Some say humans are limited in head size because of birth. Look at how funny babies look with their disproportionately large head. But density is probably more an issue for humans than for elephants.

The first deduction is probably ridiculous although we know that parts of the brain can be repurposed for other tasks if needed. We know there are completely functioning people that lost half their brain, just had to relearn some things.

Thanks for being attentive and spotting potential flaws in the article.

1. I don't really know how to answer this to you other than with "arithmetic."

2. Have you read the entire article? There is the "relative" part. Elephant's brain-to-body mass ratio is 1:560. And yes, brain size is important. Some small birds have 1:12 brain to body ratio, but that doesn't make them smarter than us.

> 1. I don't really know how to answer this to you other than with "arithmetic."

Supposing I only use 10% of my brain at any given instant, but it's a different 10% each time, then removing any of my brain would have a negative impact on me.

You've just summarized the article in that sentence. I don't have anything to add.

I kinda agree with the article just not the reasoning that got to the outcome.

1. Saying we use 10% of our brains doesn't imply 90% of the mass is unnecessary. It could be saying 90% of the electrical activity is unnecessary, or 90% of the synapses are unnecessary. I don't believe the myth, but doing a hard logic stop from 10% to that means 90% of weight is unnecessary is not implied by the statement we are arguing against. It's nothing to do with arithmetic.

2. If you look at the article one of the 1st headings is "Size Does Not Matter". So does it matter or not? When you look closer the stand out features of humans is a wrinkly grey matter, so surface area (i.e. grey matter) seems important and mass based arguments are a correlation to that. (also big bodies have more sensory area so their is an inverse correlation to body size too)

Anyway, I think the point of the myth is to say humans have more potential than their default. If you take some Ritalin or Cola you might agree that the natural brain can be souped up a bit cognitively (not by 10x). Experience and learning also gets more out of an (nearly) identically sized brain too. You can't take an experience brain and cut half of it out to become a toddler again though

Thanks for the clarification. Now it's clearer why you wrote the first comment.

1. I think you and I have different understanding of that myth. I was referring to the fact that people think 90% is not used at all. I might have done a poor job of emphasizing that thing, that's why we are discussing this now.

2. I haven't looked at it that way. It's an instance when the paragraph name interfered with some important concepts in the entire article... The point in "Size Does Not Matter" that I have envisioned is that being a such a small fraction of the body, the brain consumes unproportionately more energy.

The point of Ritalin and Cola is that those increase the blood glucose level, which aids in cognitive processes.

> I think the point of the myth is to say humans have more potential than their default.

The point of the myth is to say humans have more potential than their default ... and if you buy my book / miracle potion / herbal supplement / a ticket to my 3 day motivational lecture you can unlock yours!

> 1. That using 10% of brain means 90% can be removed. Where did that logic come from?

I suspect the thought process goes, if you're using <=10%, 90% is unused. And whats the difference between unused and not there?

Different parts of the brain actually do different things. So... which 10%?

We're always using a % of our brain, but it's constantly shifting around which regions are active.

On (2), how do we know elephants aren't more intelligent than us, but along some entirely different axis from the ones on which we excel?

Obligatory: https://xkcd.com/638/

Of course on the contrary brain size may not matter much at all. Crows can count and display many other signs of shocking intelligence despite having tiny brains. Crows may be smarter than elephants, but if so then why would evolution select elephants to have all that extra worthless metabolic load? Brain matter is costly in both energy consumption and nutrients required to grow it. It's unlikely that elephants would have hypertrophied brains if all that brain matter were doing nothing.

At the end of the day I think crows and elephants show us how much we don't know.

I'm generally skeptical of any study of elephants because they're obviously a social species and they've been very badly mistreated for many generations. Even in cases where an individual elephant may receive a lot of attention and care from compassionate humans, that elephant may still be deprived of a healthy development by being deprived of other healthy elephants to live with. And even in cases where a group of wild elephants may have lived happily undisturbed for generations, those elephants would be inherently difficult to study in detail.

That's an excellent point. How intelligent would a human seem after years of abuse and solitary confinement? Solitary confinement alone can reduce humans to near catatonia.

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