5 Brain Disorders That Started as Evolutionary Advantages

5 Bipolar Disorder Helped Us Survive the Winter (and Get Laid)

About 2.6 percent of adult Americans have bipolar disorder, along with its signature manic and depressive episodes that can last for months or even years. It makes you wonder: If it's such a common bug in our 100,000-year-old head computer, how come evolution hasn't gotten around to fixing it by now? Why would natural selection have given us brains that go nuts with activity for a stretch, then just shut down completely?

It's almost like some people have brains that are set to hibernate, like bears.

How It May Have Helped Humanity:

Oh, right. It may actually have been a form of hibernation.

There is a theory that the brains of our northern ancestors devised a way to oscillate their moods between manic and depressive to align the former with light, warm seasons and the latter with the cold darkness of winter. This would be for the exact same reasons lots of animals do it: The manic episodes turned them into superhunters and uber-gatherers who happily slaughtered and stockpiled while the sun was shining, right up until it was time to sink into wintery depression.

According to this theory, people with bipolar disorder were also masters of boning. Since bipolar disorder is most prevalent in women of reproductive age, some researchers think part of the reason the brains of prehistoric ladies dug bipolarity was sheer procreation: They turned on the manic phase during the summer, when it was most convenient to get pregnant. The subsequent winter down period would have ensured that the lady is less active and free to concentrate on the coming child, which in turn would have led to healthier offspring.

Bipolar disorder might also have been helpful as a method of sexual seduction, as affected people are drawn to artistic endeavors such as music, which, as every single rock star on Earth will tell you, doesn't exactly decrease your chances with the opposite sex. Thus, prehistoric people with bipolar disorder would have reproduced like rabbits, which helped preserve their lineage and pass along their genes.

4 Obsessive-Compulsive Disorder Was a Psychological Immune System

Obsessive-compulsive disorder turns the world into a place where things are constantly filthy and out of their proper order, sometimes to the point where the person is stuck forever fine-tuning some tiny aspect of their life for hours on end. The disorder carries the added stigma of being seen as a bit of a joke -- we all know someone who is "totally OCD" because they're meticulous about, say, keeping their bookshelf in alphabetical order. They don't know what it's like to have to wash your hands exactly 25 times before leaving the house.

Which is too bad, really, because humanity might have been eaten by horrorwolves a long time ago if it wasn't for old OCD.

How It May Have Helped Humanity:

To put it simply, the kind of obsessive attention to organization and cleaning rituals that makes somebody a neurotic mess today may have been the difference between life and death for our ancestors.

This is another case where you have to get some perspective on just how radically different the world was then. It doesn't exactly take a huge amount of mental effort to stay alive through an average Saturday of eating Cheetos and watching 12 hours of terrible direct-to-Netflix action movies, but evolution built a brain that was designed to handle a way more dangerous world. An OCD sufferer is acting like he'll die if he doesn't get every little thing in his immediate surroundings exactly right, but you don't have to go back too far in your time machine to find a world where that was absolutely true. It is thought that the condition originated as an evolutionary warning system that kept our whole species alive by making certain early humans constantly worried about everyday stuff like "Is this thing still good to eat?" "What's that approaching noise behind the woods?" and "Is Grog being carried away by that giant bird?"

As we took up agriculture and started giving up our hunting and gathering activities, we stopped using a lot of those involuntary mechanisms we had developed to dodge the various members of the animal kingdom that either saw us as food or objected to being poked with a spear. But those who kept their compulsive behaviors still had a place -- people who have OCD, for instance, get disgusted more easily, which may have originally served as a means to get them to stay away from icky things that pose a potential danger in the form of bacteria and parasites ... which in turn led to inventions such as basic hygiene.

This constant on-the-edge behavior may or may not have been frowned upon by the rest of the community, but ultimately it worked to teach everyone the essential skills of staying alive. After all, no matter how annoying the dude who insists there's a bear in the area might be, people start paying attention to him by the time the sixth guy disappears to the sound of a loud growl and a baritone burp.

3 ADHD Made Us Invent New Things Because We Got Bored

On paper, attention deficit hyperactivity disorder is a pestilence of modern times. The merest mention of the condition conjures images of schoolkids with bulging eyes and twitchy mannerisms, heads turning in different directions like a parliament of barn owls.

Still, ADHD is far from a contemporary disorder. It is a genetic condition, which means the ancestors of the poor souls suffering from it have somehow managed to survive the carnival of death and disease that is our history despite having the attention span of a hummingbird. Ever wonder how they managed that?

How It May Have Helped Humanity:

We tend to think of ADHD as a modern disease exacerbated by too many video games and rapid-fire distractions ruining young brains, but the big disadvantage of the disorder -- the inability to sit quietly and listen to a teacher drone on about long division -- wasn't always a disadvantage. That's why some theories suggest that ADHD used to be an outright survival tool.

Think about it: Modern man is a specialized creature -- some people know plumbing, others are talented guitar players, yet others still are particularly proficient in writing dick jokes on the Internet. In an environment like that, the kind of brain that likes to spend an hour doing this, then 15 minutes doing that, with no patience for sticking with one project for too long, can be downright disastrous. But go back several thousand years and you find a species that needed a wide variety of skills to survive -- no one could just be the dude who knew how to pitch a tent, or the lady who could make a mean ax. Everyone had to be a little bit of everything or the group would disintegrate the second something happened, like a D&D party that has lost its healer. In that world, you'd better goddamned well have a brain that likes to hop from task to task.

Also, because everyone was hunting for survival, not giving a shit about routine would have led them into exploring more and eventually finding the place with the best view and greenest pastures. Then, just as now, great advancement happened because capable people got bored with the status quo.

This theory is backed up by the fact that the gene associated with ADHD is common among particularly plucky and adventurous native populations. Studies have also shown that hunter-gatherers with ADHD are able to keep themselves better nourished than other people, providing them with an edge over other, less adventurous souls.

Sadly, our current way of life doesn't require much exploration, so the 11 percent of children still diagnosed with this survival supertalent are left fidgeting and staring longingly out of the window while waiting for their medication to kick in.

2 Dyslexia Is a Symptom of an Ancient Brain Superpower

Dyslexia is one of those strangely specific disorders that make you wonder just who the hell designed the human brain, anyway. It's characterized by an inability to read despite normal intelligence, the brain jumbling up characters like one of those CAPTCHA text boxes.

For these people, all sorts of mindless, everyday things you take for granted, from reading menus to browsing the Internet, become laborious chores. Luckily, most sufferers can eventually overcome the condition and excel. Or rather, turn their back on their evolutionary excellence.

How It May Have Helped Humanity:

When you look at the stats, something strange starts to jump out: According to some surveys, over 30 percent of entrepreneurs describe themselves as dyslexic, and tons of influential people -- from Albert Einstein to Steven Spielberg -- have struggled with the condition. People with dyslexia tend to be highly creative, artistic, and intelligent, and often kick ass at solving multidimensional problems.

Dr. Duncan Milne, a big name in the field of neuropsychology, says that this is not a coincidence; according to him, dyslexia is a telltale sign of exceptional brain badassitude. During our hunter-gatherer period over 200,000 years ago, there was no reading or writing; we were too busy wrestling bears and figuring out which mushrooms are edible and which ones make you visit the pink pumpkin god. Our life was all about clever ideas, efficient communication, and creative problem solving, which you may recognize as the exact damn things dyslexics tend to excel at.

When the kind of brain that is particularly talented in the important act of staying alive in the most efficient way possible is suddenly facing reading and writing -- two fairly recent inventions that radically differ from the frantic survival shit it's spent countless millennia specializing in -- it tends to view them as unnatural acts. A dyslexic brain is not stupid or even malfunctioning -- it's just wondering why it has to make sense of all these stupid squiggles when it could be out punching tigers instead.

Yes, according to this theory, dyslexia is really not a disorder at all: It was always there for the exceptional individuals whose brains had an extra edge. We just never realized it, so when someone came up with all that "reading" and "writing" poppycock, the people whose brains dared to object were looking at a ticket to Disorderville.

1 Autism Made Hunter-Gatherers Hardcore Survival Machines

Let's get the scary stuff out of the way first: Autism diagnosis is at an all-time high in the U.S. One in 88 kids is diagnosed with some form of the disorder, and it looks like the numbers are still on the rise. We have no clear idea about what causes it (no, it's not vaccines). In the face of those numbers, it's easy to assume that our genes have finally thrown their hands up in frustration and skulked in the corner to hug their favorite bottle of bathtub gin.

Well, that, or evolution is just doing its thing and providing humanity with a supply of badass motherfuckers.

How It May Have Helped Humanity:

Experts suggest that autism never had to sneak past the survival-of-the-fittest checkpoint to make it all the way to modern times. Instead, it proudly marched through the gates with a saber-toothed carcass in one hand, casually clubbing the guards over the head as it went.

While autistic people often have trouble interacting with others, the condition also provided unexpected advantages for a hunter-gatherer: Namely, it switched on the badass parts of their brain. While most of our ancestors were busy hunting and foraging in groups, the ones on the autism spectrum preferred a more solitary lifestyle. These people were able to efficiently operate alone; the time and effort that others spent socializing and drawing crappy stick figures on cave walls were instead channeled into things like tracking, getting to know the terrain, and other Rambo stuff.

Affected people are also known to engage in repetitive activities like stockpiling food and supplies, a useful talent in a world where your survival depended on those exact things. Since they were strong, skillful, and well-fed, their lack of social skills presumably wasn't much of a hindrance when it came to procreation, either. But once again, the world mutated into a less-friendly environment -- a densely populated land where every daily task requires a conversation and every workplace promotion requires skillful networking.

But who knows -- you may find a world much more suitable to someone on the autism spectrum a few hundred years from now. Or possibly sooner.

Matt Moffitt has a blog here and a Twitter here. You can check out Himanshu's occasionally updated blog here, or join him on Twitter.

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Related Reading: Speaking of disorders, did you know our brains are programmed to support our crappy taste in products? Even something as simple as a baby can hack your brain with nightmarish results. And some movies reach the level of outright mind control. But hey, at least there are some ways to hack your brain for better performance.