The idea that everyone should celebrate their birthday is, weirdly, not very old itself.
Not until the 19th century--perhaps around 1860 or 1880--did middle-class Americans commonly do so, and not until the early 20th century were birthday celebrations a tradition nationwide. In fact, the song "Happy Birthday" is not far beyond its own 100th birthday.
Throughout history there are scattered examples of birthday festivities around the globe, but the honorees tended to be either rulers, such as Egyptian pharaohs, or powerful members of an upper class. For a while, a similar pattern held in the United States: Birthdays were for rich people or national heroes. Americans celebrated George Washington's birthday, for instance, but for everyone else, a birthday--if they even knew the date--was just another day.
The shift in the mid-19th century started with kids. Some scholars have emphasized the increased attention that began to be lavished on individual children as families started having fewer of them. Kids' birthday parties may have been an early hint of how American children were starting to be viewed as less valuable economically (as workers) and more valuable emotionally (as family members).
The rise in birthday celebrations was also part of a larger shift in how people conceptualized the passing of time. Clocks in preindustrial America were "rare and seldom accurate," according to the historian Howard Chudacoff. As the 19th century progressed, the widespread production of household clocks and pocket watches made it possible for Americans to constantly know what time it was. And as more people followed the schedules of factories, streetcars, and trains, they had more reason to watch those clocks.
As Americans became more aware of time, they also became more aware of how it passed in their own lives, Chudacoff argues in his 1989 book, How Old Are You?: Age Consciousness in American Culture. This newfound focus on age was visible in many 19th-century institutions: Schools started using age to separate students into grades, and doctors started using it to assess people's health and development. Not coincidentally, this was the same era when people started noting their birthday.
The precision of and attention to time seem to be what link the process of industrialization to the observance of birthdays. As Hizky Shoham, a cultural-studies professor at Israel's Bar-Ilan University, pointed out to me, the two have coincided in other times and places, such as in Sweden in the late 19th and early 20th centuries, and in rural Estonia in the mid-20th century.
America's own period of industrialization in the 19th century was when the rituals and trappings of birthday parties went mainstream. The way we celebrate today is a mishmash of traditions: Cake can likely be traced back to ancient Roman birthday rites (though some accounts indicate that Americans used to be just as likely to celebrate with fruit). The candles appear to come from aristocratic German birthday celebrations, and date back at least several hundred years. And the expectation of wrapped gifts is a product of good old Western consumerism.
Relatedly, people started selling birthday cards in the late 19th century. Before long, card makers were releasing the same age-phobic dreck that you can find in drugstore aisles today. One 1926 card read, "I know your age / But I'll keep it mum / If you'll do the same / When my birthdays come."
Today, the idea of someone celebrating their birthday is noncontroversial, but in the decades when the tradition was still new, some groups resisted it. Researchers have noted that various birthday-party poopers thought that the celebrations were self-centered and materialistic, took attention away from God, and turned children into brats.
The haters, of course, lost. But they were right to suspect that birthdays have a dark side. As anyone past a certain age can attest, marking another year is not all balloons and ice-cream cakes. A birthday can be anxiety-provoking, in the sense that it "provides a milestone by which individuals can compare their status, accomplishments, [and appearance] with other people who are the same age," Chudacoff told me. "It's kind of like a train: Are you ahead of time, on time, or behind time?"
In fact, the era when birthdays exploded was also the era when those terms--on time, ahead of time, behind time--entered the lexicon. They were used to talk about daily logistics, but they were also applied to people's progress through life in a way that quickly laced birthdays with anxiety. "I lay in bed this morning thinking, 'forty-six years old and nowhere yet,'" one woman wrote in her diary in 1921.
A century later, cultural expectations have loosened around when and whether people should reach milestones such as getting married and having kids. But the pernicious stigma associated with being "behind time" persists. So on your next birthday, as a gift to yourself, kick back with a nice big bowl of fruit, don't look at the clock, and take the day off from neurotically comparing yourself with everyone else.