This social feedback produced sharply higher inequality in song ratings and download frequencies. In each of the eight groups, the most popular songs were far more popular, and the least popular songs far less popular, than their counterparts in the control group.

There was also enormous variability in the popularity rankings across the eight groups, and in the fates of songs with a given objective rating. The song “Lockdown,” by the band 52 Metro, is a case in point. Ranked 26th out of 48 in the objective ratings, it finished at No. 1 in one of the eight groups, but at No. 40 in another.

The most striking finding was that if a few early listeners disliked a song, that usually spelled its doom. But if a few early listeners happened to like the same song, it often went on to succeed.

That a song’s fate depended so heavily on chance doesn’t mean that success was purely a matter of luck. After all, bands that didn’t work hard and lacked even a modicum of talent wouldn’t have managed to record songs good enough to have been included in the first place.

IN their experiments, the sociologists showed how feedback could be a vitally important random effect. And it can be seen in many other situations: it’s often hard to find information about the quality of a particular product, so we rely on the reactions of friends and acquaintances who’ve already tried it. Any random differences in the early feedback we receive tend to be amplified as we share our reactions with others. Early success — even if unearned — breeds further success, and early failure breeds further failure. The upshot is that the fate of products in general — but especially of those in the intermediate-quality range — often entails an enormous element of luck.

We always knew that it was good to be smart and hard-working, and that if you were born or raised with those qualities, you were incredibly lucky, just as you were lucky if you grew up in the United States rather than in Somalia. But the sociologists’ research helps us understand why many people who have those qualities never find much success in the marketplace. Chance elements in the information flows that promote that success are sometimes the most important random factors of all.

Of course, we should keep celebrating the talented, hard-working people who have succeeded in their businesses or careers. But the research provides an important moral lesson: that these people might also do well to remain more humbly mindful of their own good fortune.