Here's Why You Can't Tickle Yourself, Plus 15 Other Weird Things I Learned About The Human Brain

I haven't been able to sleep since I learned about cysticercosis.

Brains: We all have 'em.*

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*Unless you're a jellyfish. In which case, I have a LOT of questions.

But how much do you actually know about your brain?

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Well, let me tell you — there's a lot to learn! So I decided to compile a list of strange but fascinating facts about the human brain. Here are 16 of the most interesting ones:

1. The human brain has shrunk over time.

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Today, the average human brain weighs just under 3 pounds. However, the brain appears to have shrunk over the past 5,000 years. "We do know from archaeological data that pretty much everywhere we can measure — Europe, China, South Africa, Australia — that brains have shrunk about 150 cubic centimeters, off a mean of about 1,350. That's roughly 10%," said paleoanthropologist John Hawks at the University of Wisconsin at Madison. "As to why is it shrinking, perhaps in big societies, as opposed to hunter-gatherer lifestyles, we can rely on other people for more things, can specialize our behavior to a greater extent, and maybe not need our brains as much."

2. There have been cases of people whose brains developed without the cerebellum (the part of the brain responsible for balance and coordination), and some never even knew.

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This is a rare condition called cerebellum agenesis and has been seen in a few patients. For example, one man with this condition had some speech and balance issues but still lived independently and had an office job. Another person with this condition, a 24-year-old woman, had no idea she'd been living without a cerebellum until doctors discovered it. 

3. The brain is approximately 73% water.

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Compare that with the lungs, which are estimated to be 83% water!

4. The brain has a consistency similar to jello.

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Human brains are naturally soft and squishy because they're made up of so much fat — about 60% fat, actually! The more solid-looking ones you see in museums have usually been altered for preservation.

5. The idea that you only use 10% of your brain? That's a bunch of baloney.

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It's not known exactly where this myth originates from, but it's not true. "Ultimately, it's not that we use 10% of our brains, merely that we only understand about 10% of how it functions," said Robynne Boyd at Scientific American. 

6. Your brain starts out as an itty-bitty tube.

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Your brain begins as something called a "neural tube." About three weeks after conception, the neural plate — made up of a bunch of embryonic cells — fuses into the neural tube. Eventually this all transforms into the nervous system.

7. You cannot tickle yourself because the brain anticipates your own touch, canceling out the pressure you apply.

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8. You can have tapeworms in your brain.

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Sorry to be the bearer of bad news, but yes, this is possible. The New England Journal of Medicine detailed a case in which a 38-year-old man came into the hospital complaining of seizures, only for doctors to diagnose him with cysticercosis, "a parasitic tissue infection caused by larval cysts of the tapeworm Taenia solium."

9. A brain freeze is actually a type of headache.

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Scientifically known as "sphenopalatine ganglioneuralgia," a brain freeze typically occurs when you eat something cold too quickly. Because your body wants to warm itself up, blood vessels quickly expand in the mouth. Other vessels — such as ones in your forehead — may also grow or shrink, which can cause pain signals to be transmitted to the brain through the trigeminal nerve. 

10. The brain operates on enough watts of electricity to power a small light bulb.

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Exact numbers vary, but a common estimate by scientists is 20 watts.

11. The human brain is made up of roughly 86 billion neurons.

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Also known as nerve cells, neurons are responsible for transmitting information to other cells. It was long touted that the brain contains 100 billion or more neurons, but recent scientific studies dispute that.

12. Your brain hypothetically might have enough memory to store the entire internet.

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A study conducted by researchers at the Salk Institute for Biological Studies found that the hippocampus had much more memory storage than previously thought. However, that doesn't mean we could actually memorize the entire internet — our brains aren't built to process that amount of information so quickly. "Our storage process is slower than our experience of the world," Northwestern University memory researcher Paul Reber said to Scientific American. "Imagine an iPod with infinite storage capacity. Even if you can store every song ever written, you still have to buy and upload all that music and then pull individual songs up when you want to play them."

13. There are taste-receptor cells in your brain.

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“Taste, the way you and I think of it, is ultimately in the brain,” said researcher Charles Zuker of the Howard Hughes Medical Institute at Columbia University Medical Center. “Dedicated taste receptors in the tongue detect sweet or bitter and so on, but it’s the brain that affords meaning to these chemicals.”

14. The prefrontal cortex, the part of the brain that helps with rational thinking, does not fully develop until about age 25.

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Basically, this is the part of your brain that helps with self-control, judgment, and impulse control. Kind of puts those "What were you thinking?!" lectures from your teenage years into perspective, doesn't it? 

15. An orgasm activates roughly 30 major systems in your brain.

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Not only do orgasms stimulate areas in the brain related to touch, but they also activate seemingly unrelated regions — including the limbic system, hypothalamus, and prefrontal cortex. 

16. Finally, our brains do most of their growing within the first five years of our lives.

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Scientists estimate that the brain grows about 1% every day for the first three months of life, then decreases to about .04% of growth a day. By the time someone is 5 years old, their brain is about 90% the size of an adult brain.

What kind of strange facts do you want to see next? Tell us in the comments below!