It's not a minor point; our hairlessness is a big reason why human civilization even exists. Without that natural insulation of fur covering us, we had to create clothing, and groups living in different areas produced varying levels of pigmentation to protect their exposed skin from the sun, leading to the development of our various races.

Oh, and the need to keep warm may have also contributed to our ancestors learning one other mildly important skill: making fire.

"Awesome! Let's throw some shit on here and see what happens to it."

So how did we wind up as the hairless monkeys we are today?

We were filthy.

Yes, one leading theory is that we did such a horrible job keeping our fur clean, parasites became rampant. Particularly body lice we picked up from gorillas (don't judge, the Pleistocene period was a crazy, experimental time). So eventually, not having fur for the little bastards to nest in became an evolutionary advantage, and hairless offspring became the norm. It was certainly better than, you know, washing.

Bathing is for pussies.

So if you've ever worn an outfit purely made up of the only items of clean clothing you had left, or gone to the laundromat in your pajamas because all of your clothes were so dirty you didn't think they were medically safe to wear (Yeah, you know who you are), it's time to stop feeling bad.

After all, we as a species actually went naked because we couldn't be bothered to clean our once naturally occurring monkey suit.

Well, speaking of that big brain of yours, you have it thanks to gluttony. Specifically high fat and high calorie food. There are plenty of animals that eat simple, healthy, plant-based diets, and for the most part, they don't tend to be particularly bright.

Dumb, yet delicious.

Most of the planet's sharper animals are, like humans, essentially scavengers. A certain amount of intelligence and long-term memory is required to remember which berries are a tasty treat and which will make you shit your intestines inside-out. But what vaulted humans above and beyond competing animals like rats, to the point that we build the cities and they have to crawl through our sewers?

Fat.

What we did better than them was discover ways to cram our fat faces with the richest, fattiest foods mother nature had to offer. We used tools to crack open animal bones and skulls to get to the greasy bone marrow and brains, and if we could have deep-fried the animals we caught, we would have.

Our large, juicy brains are really all that sets us apart, and they consume a huge amount of energy. The kind of energy that could only be provided by big fatty slabs of animal flesh. Experts believe that only the relentless stuffing of our faces with the ancient equivalent of fried cheese kept us going as a brainy species. And we used this increasing brain power mainly to find (you guessed it) new, creative ways to stuff our faces.

Early humanity built its whole operation around it--the parties that went out hunting ancient critters for their awesome, fatty meat contributed to the creation of the first tools, and strengthened tribal bonds. So laugh at the fat guy chowing down on buffalo wings all you want, but he's the reason your brain is complex enough to realize how hilarious he is.

First of all, scientists suspect that humans have been boozehounds since our very earliest days when we looked like something you'd hire an exterminator to chase out of your attic. Our bodies are actually designed for alcohol consumption, with portions of our livers specifically designated for metabolizing alcohol.

So human beings have been getting tanked for ages. But that just means that somehow we survived despite our drunkenness (and the fact that it helped ugly cavemen hook up), right?

Actually, some researchers think it goes way beyond that. Human beings only truly started to thrive once we developed agriculture, as it allowed us to settle down and start multiplying like catholic bunnies. And while a guy out on his own could maybe grow enough grain to feed himself and his family, to grow enough grain so that you have excess to brew beer with, well, that takes a lot of people working together. That takes a village.

And beer gnomes.

This is why when you look back at Sumer, aka the very first actual civilization in human history, you find they used half of their grain for beer. Beer was what put asses in the seats, the one big draw of city life. It was something you just couldn't get as a roaming solitary nomad. For ancient man, beer was nothing short of a wonderful promise of what civilized human life could be, distilled into liquid form.

Sorry, we teared up there for a second.

But, once again, refusing to grow up turns out to be another cornerstone of human evolution. Take that, Dad!

Human childhoods are unique in that we're born with a massive brain (just ask any woman who's had to birth one of 'em) and wriggling vestigial bodies, that grow slowly and don't really change significantly until puberty. While most animals put all their energy towards quickly growing adult-like bodies, humans instead spend our early years strengthening the pathways in our brains and absorbing information.

Our species' unique ability to pass information and knowledge from one generation to the next is due to the fact that humans essentially spend 20 years (or more) in the nest before being asked to function as an adult--an absurdly long time in the animal kingdom. And even then there is college tuition, weddings and their old room again after the divorce.

That reluctance to go out into the world you see in so many 20-somethings is left over from an instinct that has served us very well. Cracked.com: Validating man-children using science since 2006.

We're there for ya, man...

It's a good thing, too. What we now consider the nastiest use of language may be the very thing that caused it to evolve. And here's where it gets weird:

To survive, primates had to form groups (to keep away predators, obviously). Most primate societies today top out at around 50 members, and they have a strict social structure that isn't found elsewhere in the animal kingdom. Humans rose above and beyond those small groups to the point that we can keep track of up to 150 other humans before our brains get overloaded (you may have heard this theory referred to as Dunbar's Number, though Cracked likes to refer to as The Monkeysphere). It was the forming of these bigger groups that set us apart.

How did we manage it? By inventing gossip. The first uses of our more complex language (originally probably developed to coordinate hunting) was to sit around the campfire and exchange information about the ones who weren't there, behind their backs.

That use of language--that sharing of juicy secrets about who was sick, or dying, or who was mating with who--let us gather information about other members of the group who don't happen to be present. This is what the other animals could not do, and it let us create the kind of complex societies other species can barely understand.

Wait, it gets weirder.

Ever wonder why women seem to talk--and gossip--more than men? Some think it's because while the males were out hunting, it was the females who did the gossiping around the campfire.

The Flinstones had it right, AGAIN.

And of course, all of that gossiping leads to...

The deal is, our brains are about six times too big for an animal our size. Did mankind develop this massive amount of grey matter to help us in our long-standing mission to make mother nature our bitch? Not directly; even animals that aren't particularly brainy still make out OK in the wild.

No, it has to do with all of that "talking around the campfire" stuff we mentioned above. The real purpose of our huge leap in intelligence was to help us figure out those increasingly large, complex social groups. In other words, trying to navigate the perils of the lunchroom at school probably stimulates your mind more than any of your classes ever will.

Studying the skulls of our ancestors, scientists have found disproportionate growth in the parts of our brains used to construct mental simulations. Being able to play out different situations in your mind and predict possible outcomes is not just essential to surviving the social jungle, it's also the basis of all problem solving. Basically every scientific or creative breakthrough in human history can trace its roots to some sweaty palmed caveman sitting alone in his hut fretting about whether the other cavemen think he's cool.

So what does have to do with depression?

Well, some speculate that depression evolved as a way to cope, to make people separate themselves from the group in times of stress, so they could try to simulate a solution to their problems in peace. When all those connections to other members of the tribe overloaded the brain, the brain would shut them off until we could get our act together, while sulking in the corner of the hut.

So yeah, if your teenager's being an angsty little punk, don't worry, they're actually contributing the betterment of the human race. And if he's filthy, drunk and eating an entire bucket of fried chicken, holy shit. He's about to evolve into a new species.

Nathan Birch contributes to the development of the human culture with his webcomic Zoology.

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