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Olivia: We live in a world full of rick-rolls, dat bois, and grumpy cats. And marketers everywhere want their brand-building ad campaigns to go viral. Memes have gone from being a word you weren't sure how to pronounce, to the bewitching lure that gets us onto Facebook every morning. Nobody wants to miss the dank new memes.

Since you're on YouTube, you probably know what a meme is. There are a lot of different ways you could define it, but basically, a meme is a cultural idea or behavior that spreads between people without genes being involved. On the internet, a cultural idea might take the form of a grumpy cat or a demotivational poster.

But the word "meme" is older than you might think, it's actually older than the internet. It was first coined by evolutionary biologist Richard Dawkins in 1976, in his book The Selfish Gene. In that book, Dawkins proposed that a meme was like a gene for information, and that our evolution has been driven as much by memes as by our genes.

I'm gonna tell you about that idea, which means I'm spreading a meme right now. According to our current understanding of how Darwinian evolution works, life, in all of its varied and sometimes super weird forms, turned out this way as a result of genes competing with others for survival.

A gene is a set of instructions written in your DNA. Those instructions tell your cells to create proteins. With different combinations of proteins, you could end up with anything from blue eyes, to a third arm growing out of your forehead. Humans have somewhere between twenty to twenty-five thousand genes, and 99% of them are all the same for everybody. They tell your cells how to make you be a person, and not a cucumber.

The remaining one percent are what make you different from me, and me different from Neil deGrasse Tyson. The idea is that evolution is driven by the natural selection of genes. Genes that help you survive and procreate will get passed on, and genes that hurt you will die off. Or at least become less common. And this idea might be controversial.

Some people say that things like self-sacrifice, or selflessness, can't be explained by thinking of us as little meat-machines that only exist to pass on our genes. On the other hand, self-sacrifice can benefit the survival of other gene-carriers in the family and community. And selflessness doesn't impair a gene's ability to spread so much that it would be forced out of our DNA.

But one thing that really doesn't make sense is the ridiculous size of our brains. Genetically speaking, music, and art, and YouTube are probably pointless. My capacity to wonder about my place in the universe is not helping me make babies.

And, the fact that I've been able to remember how to do the Macarena since 1993 isn't going to be what keeps me alive. Our brains could probably be way smaller, and we could be way less intelligent without it being harder to spread our genes AT ALL. In fact, a smaller brain would help us spread our genes.

During birth, the humongous size of a human baby’s head can cause complications that threaten the lives of both the mother and the baby. A smaller head would mean more surviving moms and babies — and more surviving genes. So why do we have such big brains, and behaviors that don’t necessarily affect the genes we pass on?

Here’s what meme theory suggests: we didn’t just evolve to spread our genes, we also evolved to spread memes. When we say that a meme is like a gene, we mean that super literally. A meme is a carrier of information, like a gene carries genetic information; it replicates itself across a population; and competes with other memes for survival.

Genes compete with other genes because there’s only so much room in your DNA for different instructions. Successful genes flourish, while unsuccessful genes die out. Memes compete with other memes because our brain power and attention spans are limited.

So, if memes are like genes, then you’d think the memes that help us survive are the ones that get to spread. And that’s sort of true. The first memes definitely helped us stay alive. About two and a half million years before lolcat, early humans were coming up with sick memes like "making fire" and "language." Yeah — those are memes! They’re information, that spread across entire populations, by non-genetic means. And they gave a huge advantage to anyone smart enough to use them.

The thing is, genetic evolution is a lot slower than memetic evolution. Ideas can affect an entire community in just a few hours. But changing our genes takes generations. So you don’t get a gene for making fire, and a gene for speaking Basque. There are too many memes. They happen too fast. Our DNA can’t keep up.

Instead, your genes adjust to the reality that being carried around in an organism that can understand and replicate memes is a good deal for them. So genes that make you smarter start showing up. Genes that make your brain bigger. Genes that make it easier for you to replicate information.

Humans have an incredible ability to copy each other. If you show me how to do something enough times, I’ll probably learn how to do that thing. A few other animals can do this: whales, for example, can copy each other's whale song. And some species of apes will copy each other’s methods for getting ants out of logs.

But this kind of memetic replication is super rare across the animal kingdom. And humans are ridiculously good at it. If we were dropped in the middle of the woods, I could make a hatchet by banging some rocks together until you have a blade, use the hatchet to cut down some trees, then use the trees to build a shelter.

After watching me do all that just one time, you’d pretty much know how to do it, too. That is wild! And it shows you how beneficial it can be that we evolved the ability to replicate memes. But now that we have that ability, I can draw a frog wearing a top hat, riding a unicycle, and there’s a good chance you’ll decide to spread that meme, too.

Which brings us back to internet memes. The ability to replicate memes is so beneficial that our genes have adapted to make us really good at it. We are now SO good at it, that most of the memes we spread don’t benefit our survival at all. But that’s okay, because the few that do affect our survival make up for the rest. Like not going to the toilet in our drinking water. That is an excellent meme.

Memes propagate in the so-called "meme pool" by spreading from mind to mind. The most successful memes, like the most successful genes, are the ones that survive the longest, while mutating the least. For example, the idea of using something like a wagon to transport things from one place to another, instead of carrying everything around on your back, is so successful that we’ve been doing it since the dawn of human civilization.

By this measure, internet memes aren’t nearly as successful. They spread fast, but they mutate wildly, and most have a lifespan of only a few months, or even a few weeks. In other words, they act less like a gene you might find in your genome, and more like a virus.

When you’re infected by a virus, like the kind that gives you a cold, the virus doesn’t become a part of your DNA. The virus has its own DNA, or RNA, and it hijacks your cells in order to produce the proteins that allow it to replicate itself. But viruses need to mutate extremely quickly to keep being effective.

When a virus infects a cell, it attaches itself to the cell’s membrane and injects its genetic material into the cell. But your immune system fights back. It learns how to identify the virus, attacks it, and blocks the receptors on your cell that allow the virus to bond to them.

That’s why colds usually aren’t fatal. Most viruses that can infect you only have a few days in your body before your immune system wipes them out. Once everyone in your community has developed an immunity to a virus, it can’t replicate anymore, so it dies out. That is, unless it mutates. Once a virus mutates, your immune system needs to learn new tricks to fight it. Internet memes seem to work the same way.

They’re infectious as long as they can successfully mutate. Once you’ve been exposed to all of a meme’s mutations, though, it loses its effectiveness. That’s why memes from six months ago usually don’t seem that funny. Essentially, your brain has immunized you against them. Our genes have turned us into incredible meme replicators. But if we were fascinated by every meme that smacked us in the brain, we’d never get anything done. We might never get around to breeding. We’d just sit around watching videos on YouTube all day. Like... more than we already do.

So our genes also give us the ability to acclimate to new ideas and eventually block them out. When you get tired of an idea you’ve seen before, especially an idea that isn’t useful to you, that’s a sign that your mind’s meme immune system is working. But there are lots of internet memes out there, and plenty of the ones that seem to have lots of potential to go viral, never do.

So what is it about some memes that make them better at spreading than others? It might be random. In 2012, researchers at Indiana University published a study describing how virality works on Twitter. They analyzed 120 million retweets made by more than 12 million users, then created a computer model to simulate Twitter — including Twitter users.

The program randomly retweeted things. You’d think that would make all tweets equally popular... but that’s not what the researchers found. Some tweets in the simulated Twitter-verse went viral, while most were quickly forgotten.

The team proposed that this was because the simulated users had a limited attention span, and could only view a small fraction of the total number of tweets — just like how it works in the real world. So once a tweet was randomly selected to be retweeted, that doubled its chances of being retweeted again, because more people would see it. Most of the retweets wouldn’t be retweeted again; but some of them would.

And some of those would be randomly selected to be retweeted again, and again. The further a tweet spread, the more simulated users got a chance to see it, and potentially spread it. Literally random chance guarantees that some memes will go viral, while most will die off quickly.

Now, meme theory is still controversial. It’s hard to really know if we’ve evolved to propagate ideas. A lot of scientists don’t like the concept, because it’s tough to make predictions with concrete, observable results using meme theory.

And it’s tricky to create experiments that test meme theory in a way that can be repeated over and over with the same results. And those kinds of predictions and experiments are, like, the bedrock of science. It’s possible meme theory needs to be developed more before it’s ready for robust experimentation.

Memeticists will often point out that the study of memes is young, and that we shouldn’t expect to understand memes as well as we understand genes — the field is still getting off the ground. Right now, we understand very little about how our brains actually work.

Meme theory might help us learn more; or it might lead us nowhere. We don’t know yet. But it’s exciting to be able to watch the development of such a new field. Because memes, from the English language to Rare Pepe, are a huge part of the world we live in.

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