The, “We only use 10% of our brains,” bit has been widely debunked. I’ve read it and I believe it. Brain scans show our whole brain is active and not some tiny section of it.
I am with that 100%.
My questions arises from having just seen this picture of the tallest man in the world next to the shortest woman in the world.
Intellectually they are both normal (well, I assume he is, I have seen video of her and she is normal mentally). Yet clearly his brain is substantially bigger than hers. He has more neurons than she does.
So (not sure how to put this) the program “Homo Sapien 1.0”, including all the subroutines that run it including memory, can be held on some number of neurons less than this woman has.
I would suppose there has to be a lower limit to how small a human brain can be before the program “Homo Sapien 1.0” could no longer run. Whether that results in retardation as it gets smaller or just flat out fails I have no idea but I guess that at some point it works and one cell less it doesn’t like a program not having enough memory to operate.
So what are all the other neurons for in the big guy? Just moving our bodies around? In the animal world we can see small brains running big bodies but maybe we are different.
Or is it something else?
(Please do not get hung up on the computer program analogy…I know we do not operate like a computer…just used to convey an idea.)
“The number of neurons in animals of different sizes grows with the size of the brain but stays behind the volume of the brains. In fact, in small brains the neurons are packed more densely than in larger brains. In the mouse cortex there are about three to ten times more neurons per cubic millimeter than in the human brain. This is due to the proportion of volume occupied by the neuronal cell processes, which in larger brains tend to be longer for obvious geometrical reasons.”
You might want to read the entirety of that page, or at least all of the section regarding size and weight.
I don’t think you can look at that picture and even conclude that their brains are of all that significantly different sizes, let alone anything about the numbers of neurons in each brain.
Doubtful he has more neurons than she does.
First if you look carefully you’ll notice that much more of his head is face and more of hers above eyebrows. Thickness of skull, muscle mass of head, all play in. That said probably a bit bigger of a brain. After all men (larger body mass) have on average brains that weigh more than women’s brains do.
But the big point to make is that there is no reason to believe that brain volume is correlative with neuron number. Individual neurons can be of bigger or smaller size, both of their bodies and of both how far apart they are spaced and how spread out their dendritic branching is. More of a brain’s volume can be fluid and supporting cells (the glia, the blood vessels and such).
In fact it is generally believed that neuron number is pretty stable in humans from birth to old age even though the size of the brain changes significantly over that course. That factoid might be what can answer what you are getting at. Brain development over the course of a lifetime is not about increasing cell number but about changes of branching and connections between the neurons with most of those changes being the pruning away and the nature of the supporting cells.
Just having a bigger brain doesn’t do that much for the animal. If it did, the animals with the biggest brains would be the smartest. Sperm whales have brains five times as large as a human’s but they’re not five times as smart. Elephants have brains nearly 4 times as large as ours, but they’re not known to be particularly smart animals (not dumb, but not at the head of the class, either.) The brains of smart animals tend to be large in relation to the animal’s size. So a 180lb human having a 3lb brain has a much bigger brain relative to their size than a 100,000lb sperm whale having an 18lb brain.
So with the two people pictured, is his brain-to-body-size ratio hugely different than hers, or is it just scaled up proportionally?
Well, you could use a chihuahua vs great dane instead and substitute program “Canine 1.0”. The great dane’s head is almost bigger than the whole other dog so I think it is safe to say its cranium probably has more volume than the little dog by a fair margin.
Noted and interesting. road_lobo mentioned something similar above and I will have to read the link provided.
There are people who are essentially born with “no brain”, which I put in quotes because they do have a brain, but a very abnormal one. Instead of having a normal brain-like shape with its folds and generally filling the brain cavity, their brains instead form a solid and relatively thin layer with no folds on the inside of their skulls. If you took an x-ray or ct scan of their head, most of the inside of their skull would just be water (well, technically, cerebrospinal fluid).
This condition can also form after birth, where water essentially compresses the brain into a thin layer along the inside of the skull over time.
You’d think that someone with this condition would either die at birth or would be so severely mentally retarded that they would barely qualify as a human being, and in fact many people who develop “water on the brain” (technically called hydrocephalus) end up with noticeable impairment after something like 5 percent of the brain is affected. But surprisingly, some people have this condition and are walking around and being normal people without having any clue that they have it. Often, the condition is only discovered after the person dies and they perform an autopsy. In one article I read about, the guy who had this condition was a math major at a university, and had only discovered the condition because one of his professors thought he had a big head and wanted to do a brain scan just to see what was going on.
People with this condition tend to have an IQ that tops out at about 130 or so, which ain’t too shabby considering how massively deformed their brain is and how empty their brain cavity is.
Here is an article about a man who went to the hospital complaining of weakness in one leg. The article shows images of his brain, or rather, the mostly lack therefof within his skull. This man has an IQ of about 75, which is a bit low, but he leads a normal life and works as a civil servant (he’s fully capable of running “Homo Sapien 1.0” according to the OP).
This isn’t the original article I read, but it mentions the math student, and also mentions the above civil servant.
If a small brain can function just as well as a big brain, what evolutionary advantage is there to having a big brain. Why are there people with big brains?
Hard to pack in as many neurons in a functionally organized manner in a smaller mass/volume and there is something (albeit not linear) about scaling to body size.
Along the lines of this op, here’s an interesting article doing a compare and contrast of human to elephant brain. Bottom line was that the elephant brain has lots more neurons but most of them are in the cerebellum; we blow them away in cortical neurons. Take that Dumbo!
