(Bloomberg) -- Last week, the Pew Research Center published an interactive essay by Paul Taylor, which contained an animated graphic portraying the U.S. age pyramid morphing into something of a rectangle by 2060.

“It’s uncharted territory” wrote Taylor of the territory he had just put into chart form. By 2060, the U.S. will have almost as many individuals above age 85 as below age 5. But here’s a more obvious takeaway: By 2060, the millennial generation -- defined by Pew as those born after 1980 -- will be toward the top of that rectangle, with the very oldest members approaching 80. Will they still be taking selfies?

It’s easy to forget that the millennial generation is indeed a generation. Though many of these folks -- or I should say us folks, as I'm a card-carrying millennial -- are rightly called “young people” today, we will in fact grow old. “Millennial” and “young person” will not always be synonymous. So it makes sense to try to distinguish, as much as possible, which characteristics of millennials are generational, owing to the peculiarities of time and place, and which are simply evidence of youth.

Indeed, some of our bad traits (and good looks) probably have more to do with our age than our generation. Likewise, our plaid shirts are ephemeral: We think they’re hip and trendy now, but in 30 years they’ll probably be stuffed in the back of our closets, behind our practical, professional attire, waiting for our children to unearth them amid mocking giggles. Our tattoos, whether the product of one debauched night or a considered decision to stick it to the Man by sticking it to ourselves, will remain with us even after our skin has wrinkles and our hair has turned silvery white. In a 2010 Pew report, 38 percent of adult millennials reported that they had at least one tattoo, with 18 percent of the inked having six or more. (No, Mom, not me.)

I started thinking (and writing) about this distinction last spring. In a Time cover story Joel Stein declared: "The incidence of narcissistic personality disorder is nearly three times as high for people in their 20s as for the generation that's now 65 or older, according to the National Institutes of Health; 58% more college students scored higher on a narcissism scale in 2009 than in 1982.” The Wire’s Elspeth Reeve replied to Stein's discussion of narcissism by highlighting another paper on NIH.gov and noting, "Basically, it's not that people born after 1980 are narcissists, it's that young people are narcissists, and they get over themselves as they get older.”

The New York Times ran a piece last month, "Millennials at Work: Young and Callow, Like Their Parents," that quoted Peter Cappelli, director of the human resources center at the University of Pennsylvania’s Wharton School. "There’s no evidence millennials are different" from baby boomers, he said. "They’re just younger.” Still, according to the article, many supervisors do perceive problems with millennial work habits, many millennials themselves agree with "some of these negative views" (yeah, well I have a negative view of our generational team spirit), and “academics who study this generation said its members did differ from Generation X and baby boomers” -- and that our quirks may endure throughout our working years.

Of course we differ. We were raised in a different social landscape than our parents, and many of us came of age in an especially brutal economy.

As Pew has suggested, we don’t always have sufficient data for robust inter-generational comparisons, and even if we did, it’s seemingly impossible to fully tease apart the various forces that drive differences between age groups at a given time. But some historical data can help us begin to recognize what’s unique to millennials.

In last month’s Pew report, “Millennials in Adulthood,” which concentrated on millennials ages 18 and over, we learned that "Despite their financial burdens, Millennials are the nation’s most stubborn economic optimists." But, "when Gen Xers were the age Millennials are now, they were equally upbeat about their own economic futures. Some of this optimism, therefore, may simply reflect the timeless confidence of youth." Indeed, if you compare employed millennials in 2014 (ages 18 to 33) with employed Gen Xers in 1994 (ages 18 to 29) you find a similar cheeriness about perceived future finances. Pew also points out that, "Gen Xers were coming of age in a much more favorable economic environment than today’s Millennials find themselves." Perhaps they were shrewdly optimistic, and we’re just delusional.

The report indicated that millennials are less "likely to say they believe in God" than older generations (though, to be sure, most still do); however, “if past is prologue, these young adults may develop a stronger belief in God over the course of their lives, just as previous generations have.” So too, "Millennials’ relative hesitancy to describe themselves as patriotic may be the result of their stage of life rather than a characteristic of their generation. When Gen Xers were at a comparable age, they were much less likely than their older counterparts to embrace a similar self-description."

There are genuine distinctions. As Pew notes, “Millennials are the most racially diverse generation in American history.” In addition, “fully a third of older Millennials (ages 26 to 33) have a four-year college degree or more -- making them the best- educated cohort of young adults in American history;" millennials have “at or near the highest levels of political and religious disaffiliation recorded for any generation in the quarter-century that the Pew Research Center has been polling on these topics.”

The percentage of adult millennials who are married is lower than for previous generations when they were in the same age range. More millennials are living at home: According to a Pew analysis of U.S. Census Bureau data, the proportion of 18- to 31-year-olds living in their parents homes in 2012 was the highest in at least four decades. We’re not buying cars: As Jordan Weissmann wrote for the Atlantic in 2012 (of an age group that admittedly pushed past Pew’s upper limit on millennials), "According to CNW Marketing Research, Americans between the ages of 21 to 34 purchased just 27 percent of new cars in 2010, down from 38 percent in 1985.”

As we do our best to differentiate the vagaries of youth from the particularities of the millennial, things get a bit confusing because one of the clearest markers of the millennial generation is that, by traditional indicators of “adulthood,” we don’t seem to be growing up very fast (or at all?).

I’ll leave you with this gem from Pew, based on a 2014 survey: "Millennials are the only age cohort in which more say that government programs benefiting younger people should be a higher priority than programs benefitting older people (53% vs. 31%). There is especially strong support for programs to aid the young among the youngest Millennials (ages 18 to 25)."

Yeah, ask us that one again in 30 years.

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