Note: This is a “classic” Interesting Thing of the Day article from over 10 years ago. It has not been edited recently, so it may contain broken links, outdated information, or other infelicities. We plan to eventually update or retire most classic articles, as time permits.

Several years ago, a friend of mine gave me a book for my birthday called Thought Contagion. I had not heard of the book or its subject matter, the science of memetics, but I was fascinated by what I read. Author Aaron Lynch explained, concisely and convincingly, how some of the most significant beliefs in society came to be as popular as they are. By the end of the book I felt I understood, for the first time, a great many things that should have been obvious all along. I was even more surprised to discover that the things Lynch was saying were considered novel, and even somewhat controversial. What he described, simply and elegantly, is a compelling theory about the way beliefs spread.

What Memes May Come

The fundamental term in memetics is meme, which means a self-propagating idea. The term was borrowed from sociobiologist Richard Dawkins, who coined it in his 1976 book The Selfish Gene. Roughly speaking, memetics applies the principles of evolution by natural selection to beliefs. In conventional evolution, genes that improve an organism’s ability to survive endure in future generations and spread throughout a population; those that hinder survival eventually disappear. By analogy, memetics says that ideas are subject to natural selection as well; those that most effectively promote their own survival multiply and spread, while those that don’t, don’t.

In memetics, it is misleading to think of a person as having a belief; instead, it is more accurate to think of beliefs as acquiring people. Memes propagate from person to person in a manner analogous to the way viruses spread. A meme is passed from one person to another through one form of contact or another, and in some cases must mutate in order to continue surviving and spreading. Thus memetics is sometimes described as an epidemiology of ideas, investigating them in much the same way as a researcher might study the way a disease spreads throughout a community. This is not to say, of course, that all ideas that spread are negative ones, as the analogy to disease might suggest. Memetics itself is neutral with regard to the value of beliefs, and the principles apply equally to positive, useful beliefs as to destructive ones.

Being Fruitful and Multiplying

Just as a virus can spread by floating through the air, by skin contact, or through exchange of bodily fluids, there are a number of different mechanisms whereby beliefs spread. One of the most common and effective means of spreading a meme is simply having children, because children more often than not serve as hosts for the same memes as their parents. Thus memes that encourage procreation directly (“your biological clock is ticking”) or indirectly (“abortion is murder”) serve to propagate themselves to the children of the meme’s host. Similarly, memes that make it more likely that parents will pass a belief on to children (such as “children should respect their parents”) encourage their own propagation.

Another common mechanism of meme propagation is proselytism. Consider the meme “those who do not believe in Religion X will spend eternity in hell.” This meme aids its own propagation, because holding the belief increases the likelihood that it will be transferred to other hosts. A person who considers belief in Religion X crucial to eternal happiness will be motivated to influence its adoption by friends and even strangers (not to mention offspring). This meme also illustrates other methods of propagation, such as discouraging hosts from dropping the belief (persistence of the belief, especially at the time of death, is regarded as crucial to its effectiveness) and resisting efforts of competing memes (such as “all religions are equally good”) to displace it.

Gimme Some Truth (or Not)

Of the other methods of meme propagation, surprisingly, one of the least effective is for a meme simply to seem true. The sheer force of logic can and does cause memes to spread (as in “Earth revolves around the Sun”). But more often than not, competing memes with other methods of propagation win out over those that depend solely on truth or plausibility. In particular, political and moral beliefs (which typically spread by offspring production, proselytism, and dropout prevention) usually displace beliefs whose only mechanism of reinforcement is objective fact. This could help to explain, for example, how a nation might muster public support for a war in the absence of objective evidence of danger from an enemy.

The basic principles of memetic theory that describe the ways in which beliefs spread, persist, and recede, can account for the rise and fall of numerous widespread beliefs, including economic trends, pro- and anti-abortion movements, terrorism, racism, diet fads, and hundreds of other memes. It can explain how TV programs or radio talk shows gain and lose popularity, why less effective technologies win in the marketplace over more effective ones, and how public opinion can shift rapidly on many major issues.

My predominant thought while reading Lynch’s descriptions was, “Well, of course that’s why so many people believe such-and-such. It’s obvious. How could it be any other way?” And yet, that is precisely what’s interesting about memetics: it points out and explains things that should have been obvious all along, but weren’t. Although Thought Contagion is written for a general audience and therefore avoids complex mathematics, memetic theory is in fact a very serious science, backed up by increasing amounts of highly technical analysis. Very few professionals currently consider themselves full-time memeticists, but that is certain to change, thanks to the rapidly spreading meme, “memetic explanations rock.” —Joe Kissell

More Information


div>Thought Contagion: How Belief Spreads Through Society is the best place to start if you want to learn about memetics. Also check out <a href=”″”>cover art

Aaron Lynch’s 1996 book Thought Contagion: How Belief Spreads Through Society is the best place to start if you want to learn about memetics. Also check out The Selfish Gene by Richard Dawkins.

There have been a number of reviews of the book, some more complimentary than others; see, for example, this moderately critical review by Cosma Shalizi.

Other sources for information on memetics include the alt.memetics newsgroup, Meme Central, the peer-reviewed Journal of Memetics, and Anders Sandberg’s Memetics page.