A new study on the differential earning power of male and female movie stars beings with a quote from Jennifer Jason Leigh:

It’s the nature of the business. People equate success with youth (source).

She’s half right.   Irene Pater and her co-authors looked at the pay of 265 actors and actresses who appeared in Hollywood films from 1968 to 2008.  They found that the average earnings of actors rises until the age of 51 and remains stable after that.  The average earnings of actresses, in contrast, peaks at 34 and decreases “rapidly thereafter.”

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Source: USA Today

Sarah Jessica Parker, then, was more on the mark:

There is still a discrepancy in earning power between men and women in Hollywood. And it becomes doubly unfair when you think of our earning potential in terms of years.  Actresses are like football players. They have a small window of prime earning ability (source).

So, is this sexism or just “market forces”?  That is, is female acting work devalued compared to men’s because people in positions of power don’t value women?  Or is it because casting women over 34 decreases box office returns, whereas casting older men does not?  Pater and her colleagues suggest that it’s sexism.  One study, they explain,

…actually examined the combined effect of gender and age on box office performance [and] revealed that casting a female lead older than 32 years of age does not influence a movie’s box office performance, whereas casting a male lead older than 42 decreases box office revenues by almost 17% (source).

So the presence of male actors in their forties and over decreases box office revenue, but they still get paid more than women of the same age.  In contrast, casting women in their mid-thirties and over doesn’t bring down profits, but she’s still less valuable in the eyes of producers.  Sexism sounds like a plausible explanation to me.

Lisa Wade, PhD is an Associate Professor at Tulane University. She is the author of American Hookup, a book about college sexual culture; a textbook about gender; and a forthcoming introductory text: Terrible Magnificent Sociology. You can follow her on Twitter and Instagram.