Popular baby names come and go — and math may explain why

PITTSBURGH, Pa. — Baby name trends come and go. From pop culture characters to celebrities in the news, parents take inspiration from plenty of sources when naming their children. So how does a name like Emily go from in-vogue one year to out of fashion the next? Researchers from Carnegie Mellon University say the answer may come down to one surprising factor — math.

Their study used a mathematical model to understand why baby names gain and then lose popularity over time. Even when analyzing constantly shifting behavioral patterns, the math shows there’s a continuous “tug-of-war” between parents wanting to stand out from the crowd and wanting their child to fit in as well.

“I am curious about everything, but I am clueless about popular social trends,” says Russell Golman, an associate professor in CMU’s Social and Decision Sciences Department, in a media release. “My interest was sparked by thinkers in the field of complex systems who study non-equilibrium dynamics in the economy and society.”

Can social networks fit into this equation?

Most math studies looking at economic issues and game theory (which examines strategy in competitive situations) eventually reach a middle point where everything breaks even — the equilibrium.

“I wanted to use math to describe two conflicting motives — wanting to fit in and wanting to stand out at the same time,” Golman explains. “They push you in opposite directions but you can want both things.”

The study author adds that the desire to fit in when naming a child would move the model closer to the equilibrium. Conversely, wanting to pick a name that stands out moves the parent’s behavior away from the middle ground.

“Put them together,” Golman continues, “and they still lead to equilibrium.”

The study author wanted to see how many different social factors researchers could throw into these models before they buck the trend. To do this, Golman and his team added the behavior of various social networks to the mix, including communities, neighbors, colleagues, clubs, or other social groups. However, researchers note social networks aren’t necessarily the same as social media.

“It was surprising that social networks could make such a big difference,” Golman says. “We modeled the dynamics with a lot of different networks, and not converging to equilibrium is actually pretty typical.”

Parents pick names which fit in — with a twist

PhD student Erin Bugbee used a large database of baby names coming from the Social Security Administration over the last 100 years to analyze parental behavior. According to mathematical models, if baby names really settle into the equilibrium, then the same names would always be popular each year.

What the study authors found was that parents actually take popular names (like Emily), and then pick something similar — like Emma. For parents, the study finds this name gives a child something that both stands out but is also socially acceptable in comparison to the most popular names of the time.

Interestingly, the math shows plenty of moms and dads arrive at this conclusion and do the same thing! The end result is that a name like Emily actually becomes less popular and a name like Emma enters the most popular baby name lists.

The findings appear in the journal Psychological Review.