Zoologist Richard Dawkins coined the word "meme" in his book on evolution, The Selfish Gene, in 1976. In it, he wrote:
Examples of memes are tunes, ideas, catch-phrases, clothes fashions, ways of making pots or of building arches. Just as genes propagate themselves in the gene pool by leaping from body to body via sperms or eggs, so memes propagate themselves in the meme pool by leaping from brain to brain, via a process which, in the broad sense, can be called imitation.
This video (Thank, Mister44!) by CGP Grey looks at what has happened to meme propagation in the era of the Web. He calls them "brain germs" instead of memes, because the word meme is now more closely associated with photos with text on them (which *are* memes, but not the only memes). CGP Grey says that hateful ideas spread faster than happy or sad ideas, and that they mutate into super-hateful fake news thought germs.
Thought germs can burn out because once everyone agrees, it's hard to keep talking and thus thinking about them. But if there's an opposing thought germ, an argument, then the thinking never stops. The more visible an argument gets the more bystanders it draws in which makes it more visible, which is why every group from the most innocuous internet forum to The National Conversation can turn into a double rage storm across the sky in no time.
Wait, these though germs aren't competing, they're co-operating. Working together they reach more brains and hold their thoughts longer than they could alone. Thought germs on opposite sides of an argument can be symbiotic. One tool that symbiotic anger germs can employ is you're-with-us-or-against-us. This makes it hard for neutral brains to resist, and its divisiveness also grows its symbiotic partner. This explains why, in some arguments, gaining more allies also gains more enemies. Because though the participants think they're involved in a fiery battle to the death, from the anger germs perspective one side is a field of flowers and the other a flock of butterflies.
