In the upcoming film Lucy, Scarlett Johansson is a drug mule filled with brain-expanding blue jelly. When the bags inside her accidentally break, the chemicals inside unlock her brain’s hidden potential. Her newfound abilities are so amazing that Morgan Freeman has to teach a class on them.
But you are just as incredible as Lucy. While you won’t be able to throw a Japanese gangster through a wall with your mind, the human brain is still capable of amazing things. We already use 100 percent of our brains, and here are 10 reasons* how we know we are all like Lucy:
1. Human brains use way too much energy to be mostly nonfunctional.
While the brain makes up less than five percent of our body weight, it uses a full 20 percent of our energy reserves—more than any other organ. While it’s not out of the question that one tenth of an organ could be that hungry for energy, we see direct changes to the brain whenever we are low on nutrients, implying all of the brain is whirring away all the time.
All that energy goes to good use. Although the most powerful supercomputer in the world—the K computer from tech company Fujitsu—can compute problems four times faster than one human brain, it uses enough electricity to power 10,000 homes doing so. One brain can handle 25 percent of the load of the world’s faster computer using only the energy required by a 100-Watt light bulb.
2. Medical scans have never found any completely nonfunctioning area in the brain.
For the last few decades we have used incredibly intricate physics to generate detailed pictures of the human brain. For example, we can put someone in an fMRI (functional Magnetic Resonance Imaging) scanner and look at where the blood is flowing to determine active areas of the brain. But over the course of probably hundreds of millions of these scans, we have never encountered an area of the brain that doesn’t eventually light up. We may not know why an area of the brain lights up, but all of them do.
There are still so many mysteries of the mind. Even knowing that we use 100 percent of our brains—not all at once, but all of it over time—we have no idea what much of the brain does. We don’t even know what consciousness is, and that’s the most fundamental aspect of human life! Enough problems are left unsolved that neuroscientists would love to ignore 90 percent of the brain and focus in on where the action is. They can’t; there’s too much science left to do.
3. Damaging any area of the brain damages the mind.
If we only used 10 percent of our brains, we would be incredibly resistant to brain damage. Think of it this way: Could someone poke a pencil into your head 10 times and you would be completely unaffected nine of those times? In reality, we know that even tiny alterations to the brain can lead to lasting and fundamental changes.
That’s not to say that we can’t work around brain damage. So-called “neuroplasticity” is the idea that the brain can re-wire itself to compensate after damage or to learn a new skill. Consider the case of Phineas Gage, the go-to example of all psychology textbooks. This ordinary man had a spike rocketed straight through his head. He survived, but his personality changed. He was not the man he used to be. The fact that he was able to function at all is testament to the brain’s ability to compensate. He would have wished he only used 10 percent of his brain; if that were true he probably would have been fine.
4. Evolution isn’t nice enough to let such brain potential go to waste.
Random mutations, selected over time by environmental pressures and procreation, eventually leads to better-adapted organisms. That’s evolution in a nutshell. But evolution only uses the tools available to it, and it isn’t kind. Trillions of organisms have fallen by the wayside of evolutionary history. 99.9 percent of all the species ever on Earth are currently extinct. So it’s extremely unlikely that random mutations would first produce a mostly useless brain and then nature would select for it. Where’s the advantage to having no advantage? In fact, if we did only use 10 percent of our brains, there would be a large survival advantage to humans with smaller, more efficient brains.
We are the evolutionary winners when it comes to brainpower. While a chimp is our closest genetic cousin, for example, it has ten times fewer neurons than a human, correlating with decreased intelligence. In terms of brain size versus body weight, humans are far and away the leader in the qualities we think leads to high intelligence.
5. Brain functions are spread out enough that not using 90% of them would kill you.
Despite what the colorful infographics will tell you, you aren’t a “left-brain” or a “right-brain” person—you are a whole brain person. While some brain functions, like speech, are partially localized to one side of the brain or the other, most of what the brain does is spread out across a large area. When everything is so spread out, only using 10 percent of the brain would be like only seeing 10 percent of a collage; it would cease to be what it is.
There are redundant systems in the brain, making it highly adaptable. When a patient has terrible epilepsy, for example, one last-ditch surgical solution is to cut the corpus callosum. The corpus callosum is a bundle of nerves that connects the two brain hemispheres, and cutting it can help stop seizures from spreading all over a patient’s brain. The brain can overcome this severing of communication. In fact, these “split-brain” patients tell us fascinating things about how our minds work. In one amazing test, researchers put an object in the right hand of a subject with a split-brain. Because of how the brain’s functions are spread out between hemispheres, the subject could verbally describe the object but could not physically see or hear it.
6. On any scale, we find that everything in the brain is doing something.
In some cases, researchers have been able to insert electrodes into the brains of surgical patients to record the activities of single neurons. No matter where the electrodes are placed, there are neurons firing (see where we are going with this?).
The human brain has around 86 billion neurons. That’s not quite as many as the stars in our galaxy (between 200 and 400 billion), but it’s still more than any other animal that we know of. If we only used 10 percent of those, we would be on the neuronal level of an adult zebra fish, and below a frog.
7. We check out your brain when you die, and most of it isn’t mush.
In the human body, “if you don’t use it, you lose it,” holds true a lot of the time. When astronauts aren’t able to exercise their muscles and bones properly, for example, their bones can start wasting away at the rate of 1 percent (or more) per month. Because the brain uses so much of the body’s resources, we can imagine that shutting off 90 percent of the brain would turn the same amount to jelly as well. At every autopsy, we should see brains that are mostly goop, but we never do.
It may be true for some parts of the body that if we don’t use them we lose them, but the brain at least has a way around that. When we first started studying the brain it was a truism that once brain cells die, they are never replaced. We only recently discovered that this isn’t true. Called neurogenesis, our brains recruit neural stem cells that become full-fledged brain cells and make all the same connections that normal brain cells do!
8. A lot of mothers would be mad if that big head held mostly unusable brain.
Having a huge brain complicates birth. Human babies’ giant heads are a tight-squeeze, so to speak, and the ordeal of birth can damage mother’s spines or worse. If we only used 10 percent of our brains, evolution would impose a huge selective pressure to shrink the size of the human skull to only accommodate useful material, if for no other reason than that it would help the species procreate successfully.
We have artificially imposed the problem of birthing a creature with a huge head on our dogs. Over 80 percent of bulldogs are born by caesarian section because we have artificially selected and bred for bulldogs with enormous heads. The little pups can no longer physically pass through the mother’s birth canal. Without artificial selection, the human brain must be pretty amazing to impose such a high risk on our mothers. (Modern medicine helps, but we’ve only had that for a century or so.)
9. The brain is buzzing even when you imagine it’s silent.
The best case that the 10 percent myth can make is that parts of our brain occasionally seem inactive. But thoughts can be deceiving. Even when we sleep, our brains keep computing, consolidating the events of the day into long-term memory and crafting bizarre dreamscapes.
In fact, because we use all of our brains over the course of a day, we can afford to shut off certain parts when necessary. Ever feel like you just can’t think straight when you are sleep-deprived? You’re right. Researchers have found that after long periods of staying awake, some neurons in the brain will go into “offline mode,” catching some needed rest while you continue to stay up. This division of labor is only possible because we have all of the brain at our disposal. Dolphins take it one step further. To get some sleep at sea, bottlenose dolphins can put a whole half of their brain into offline mode. Neurons in one half “rest” while neurons in the other half make sure there aren’t predators around and that the dolphin keeps breathing unimpeded. After a few hours, the hemispheres switch.
10. Brain tumors can change who you are.
Over the last few years, modern neuroscience has given us insights that would have astounded doctors even 50 years ago. Chief among them is the conclusion that, to put it glibly, the mind is what the brain does. Changing one part of the brain can fundamentally change who you are. No clearer is this fact than when mental illness or brain abnormalities change human behavior. When a seemingly good man goes on a killing rampage, only discovered to have a nickel-sized tumor in his brain pressing on areas critical for emotional regulation after his death, it’s shockingly clear how much changing the brain can change the person. Cases like this one raise questions about free will, legal agency, and criminal punishment, but they also answer definitively: we use all of our brain, and if you tweak even a small percentage of it there are tremendous consequences.
If only there was some pill like Bradley Cooper took in Limitless or a bag of sparkling blue drugs like in Lucy that could vault us into the realm of geniuses or even masters of matter. It’s a seductive thought. But the truth is that you used nearly 100 percent of your brain just reading this article, shifting in your seat, day dreaming, and maybe eating a snack while you did so. And that’s OK! We don’t need one more reason to be jealous of Scarlett Johansson because the human brain is already beyond description. It’s mysterious, essential, and the most complicated combination of matter in the universe (that we know of). In truth, even if Lucy could unlock some hidden brainpower, she still would have a hard time improving on what you have pulsing beneath your scalp right now.
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IMAGE: Universal Pictures
Kyle Hill is the Chief Science Officer of the Nerdist enterprise. Follow the continued geekery on Twitter @Sci_Phile.
*Much of this post is based on the book chapter, “Whence cometh the myth that we only use ten percent of our brains?” in In Mind-myths: Exploring Everyday Mysteries of the Mind and Brain, neuroscientist Barry Beyerstein.
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