Nothing captures the depth and dimensions of a generation gap like popular music. Parents, mystified (or horrified) by their children’s taste—“How can they listen to that stuff?”—harken back to their own youth, when the Rolling Stones or the Bee Gees or Prince ruled the charts. Confronted by the recent recombinant country-rap smash “Old Town Road,” they shake their heads, turn up the soothing sounds of “Sympathy for the Devil,” and marvel at how much and how fast things change.
But do they really do so?
“We’re always incredibly impressed by how quickly modern culture changes,” says evolutionary biologist Armand Leroi, “especially as we age and lose track of the new music and all the stuff that’s happening. That impression is wrong, however. And the reason it’s wrong, to put it very simply in musical terms, is that the songs change but the music kind of stays the same.”
Leroi and his colleagues explore that idea in a new study that compares the rates of evolution of certain cultural phenomena—pop music, automobiles, medical literature and 19th-century novels—with those of the scarlet tiger moth, the Darwin’s finches of the Galápagos Islands and two other well-studied creatures: a snail and another moth. As the paper notes, these particular animals had been examined by biologists over the years “precisely in the hope” that they would demonstrate evolution in action over decades. Data suggest, it adds, that the creatures represent the “upper limits to the rate of organic evolutionary change.”
The researchers’ results, published this week in Nature Human Behaviour, show that the evolutionary pace of modern culture is generally the same as that of many animal populations—which is to say, it is a lot slower than people think. “We know that organic evolution isn’t as slow as what Darwin thought,” says Leroi, a professor at Imperial College London. “But still, there’s the belief that culture evolves really fast. So we measured it.”
The cultural data sets Leroi and his colleagues used in the paper—which, they say, is the first study of its kind—were 17,094 songs that entered the Billboard Hot 100 chart of hits in the U.S. between 1960 and 2010; 2,210 fossil-fuel-powered car models sold in the U.S. between 1950 and 2010; 2,203 American, Irish and English novels published between 1840 and 1890 and collected by the Stanford University Literary Lab; and 170,577 clinical articles published in the British Medical Journal (now the BMJ) from 1960 to 2008.
For each of those cultural “populations,” as the paper refers to them, the researchers identified scores of specific traits and characteristics, such as loud guitar and smooth harmonies in pop songs; engine power and wheelbase length in cars; various medical subjects in the BMJ; and topics such as “English aristocracy” and “grief and sorrow” in the novels.
The team used advanced statistical methods to track the frequencies and values of those traits over time. The paper notes, for example, that loud guitars showed “a consistently high average frequency” and were still preserved in Lenny Kravitz’s “Fly Away” in 1998.
This computer-based procedure, analogous to measuring finches’ beaks over time, enabled the researchers to determine the “evolutionary trajectories,” or rate of change, of the four cultural populations. The paper concludes that these trajectories were comparable to those of the four organic populations they looked at, which were “some of the most famous long-term studies of animal evolution in the wild.”
The best known of these studies—thanks to the Pulitzer Prize–winning book The Beak of the Finch, by Jonathan Weiner—is the work of married evolutionary biologists Peter and Rosemary Grant, who spent nearly 50 years studying Darwin’s finches. “What they found is that they could actually see evolution happening right in front of their eyes as conditions on the islands change,” Leroi says, with unmistakable excitement. “An El Niño comes along, vegetation changes, seeds change, and the beak of the finch evolves accordingly in response to that environmental change.”
The idea that rock and roll evolves at roughly the same pace as Darwin’s finches may surprise people who were around in the 1960s for the British Invasion, the birth of folk rock and the meteors that were the arrivals of Bob Dylan and Jimi Hendrix. But things have a way of averaging out, Leroi notes. “Even if you see lots of change over a short period of time,” he says, “there may not be much change over a long period of time”—for example, the 50 years from 1960 to 2010.
And what are the forces that could be keeping these cultural populations relatively conservative? In their paper, Leroi and his co-authors suggest the answer is a variation on natural selection they call cultural selection “that, in turn, rests on known psychological biases in aesthetic appreciation.” Such selection is about “our love of the familiar,” Leroi says. “Producers are attempting to make things that consumers want, so [both of them] are typically conniving together in a way that means that culture is actually remarkably conservative.”
He offers the example of an artist who “figures out that we haven’t had a lot of guitar rock recently, and guitar rock suddenly sounds really nice and fresh again. And back it comes, and it makes the charts, and people imitate it. And then they get too much of it, and it goes away for a little bit. But the know-how, the rules of making guitar rock, are always there, waiting to be picked up again.”
If the findings of the study are borne out in future work, says Thomas Talhelm, an associate professor of behavioral science at the University of Chicago Booth School of Business, artists and entrepreneurs should take note. “For example,” says Talhelm, who was not involved in the research, “the idea of a deep stasis in music, perhaps masked by new packaging of different genres, might influence how musicians think of their craft or how novelists think about what innovation means.” He says it is also worth asking what the exceptions are. “What led to the sudden shocks in the system, like the invention of the combustion engine?” he says. “And what does that tell us about how to create the next one?” If there’s any weakness in this approach, Talhelm adds, “it’s that the answer may entirely hinge on how we define what counts as evolution, as a breakthrough.”
A 2012 study in PLOS ONE seems to contradict Leroi’s results, showing that the rate of evolution from year to year proceeds at a 50 percent faster pace for archeological artifacts than it does for organic traits. Different outcomes, Leroi’s Nature Human Behaviour paper suggests, may result from distinct research methodologies and from choosing not to study the most rapidly evolving animals. The authors of the new study also acknowledge that some technologies may indeed evolve at a quicker rate than organisms.
Leroi, who wrote a book about Aristotle’s time on the Greek island of Lesbos entitled The Lagoon, does not claim to be the only one looking at cultural evolution, but the newness of the pursuit excites him. “To me, the beauty of all this—speaking generally as an evolutionary biologist—is that it’s an open field,” he says. “You have this entire new world of culture to explore. You feel like Aristotle standing on the shore of the lagoon, saying, ‘Wow, there are all these creatures out there. Let’s invent the science called biology.’”