Back in 2005, we linked to an extremely insightful article by Frederica Mathewes-Green on why Hollywood's leading men and women all appear to be overgrown adolescents, in contrast to the stars of the 1930s and '40s, who look, especially in retrospect, astonishingly mature and sophisticated:

Characters in these older movies appear to be an age nobody ever gets to be today. This isn’t an observation about the actors themselves (who may have behaved in very juvenile ways privately); rather, it is about the way audiences expected grownups to act. A certain manner demonstrated adulthood, and it was different from the manner of children, or even of adolescents such as Judy Garland and Mickey Rooney.

Today actors preserve an unformed, hesitant, childish quality well into middle age. Compare the poised and debonair Cary Grant with Hugh Grant, who portrayed a boyish, floppy-haired ditherer till he was forty. Compare Bette Davis’ strong and smoky voice with Renée Zellweger’s nervous twitter. Zellweger is adorable, but she’s thirty-five. When will she grow up?

In a review in the Village Voice of the film The Aviator, Michael Atkinson dubbed our current crop of childish male actors “toddler-men.” “The conscious contrast between baby-faced, teen-voiced toddler-men movie actors and the golden age’s grownups is unavoidable,” he wrote. “Though DiCaprio is the same age here as Hughes was in 1934, he may not be convincing as a thirty-year-old until he’s fifty.” Nobody has that old-style confident authority any more. We’ve forgotten how to act like grownups.

And oddly enough, it works for teenage characters as well: in Opinion Journal Jennifer Graham compares Hollywood's latest version of Nancy Drew with her author's original intentions. Graham explains why Hollywood lowered Nancy's age from "either 16 or 18 years old, depending on the driving laws of the time" of the original books, as Graham writes, to about 12:

In the books, Ned Nickerson, Nancy's "special friend," is a hunky college football player. Theirs is a chaste relationship; they dance sometimes and take strolls in the moonlight, but rarely do they even kiss. In the movie, there is no mention of college, and boyish Ned is little more than a sycophantic satellite for Nancy. They share one kiss, and it's fleeting and sweet, in one of Mr. Fleming's few nods to the original. But for a movie heroine to be sexually innocent these days, she can't have graduated from ninth grade yet.

In the late 1960s and '70s, Hollywood underwent "a youth movement", as the phrase of the day called it. In 21st century America, life expectancies have never been longer. But whether it's a 30-something leading man or a fictional teenage girl detective, Hollywood paradoxically demands that everyone on screen act younger and less mature than ever.

(H/T: Galley Slaves.)