H
uman sexual activity affects cognitive func-
tion, health, happiness and overall quality
of life—and, yes, there is also the matter of
reproduction. The huge range of benefits
is one reason researchers have become
alarmed at declines in sexual activity around the world, from
Japan to Europe to Australia. A recent study evaluating what
is happening in the U.S. has added to the pile of evidence,
showing declines from 2009 to 2018 in all forms of partnered
sexual activity, including penile-vaginal intercourse, anal sex
and partnered masturbation. The findings show that adoles-
cents report less solo masturbation as well.
The decreases “aren’t trivial,” as the authors wrote in the
study, published on November 19, 2021, in Archives of Sexual
Behavior. Between 2009 and 2018 the proportion of adoles-
cents reporting no sexual activity, either alone or with part-
ners, rose from 28.8 to 44.2 percent among young men and
in 2009 from 49.5 to 74 percent among young women. The
researchers obtained the self-reported information from the
National Survey of Sexual Health and Behavior and used
responses from 4,155 people in 2009 and 4,547 people in 2018.
These respondents to the confidential survey ranged in age
from 14 to 49 years.
The study itself did not probe the reasons for this trend.
But Scientific American spoke with its first author Debby
Herbenick, a professor at the Indiana University School of
Public Health–Bloomington, and Tsung-chieh (Jane) Fu, a
co-author of the paper and a research associate at the school,
about underlying factors that might explain these changes.
[An edited transcript of the interview follows.]
Given that research in other parts of the
world has already indicated decreases in
partnered sex, what do your recent findings
add to the picture?
HERBENICK: Our study tracks the declines, too,
and extends the research because Jane [Fu] and our
larger team tracked sex behaviors in really detailed
ways. We looked at penile-vaginal sex, partnered
masturbation, and giving and receiving oral sex. We
saw declines across all categories. And we included
adolescents, too. The decline in adolescent mastur-
bation is interesting, and we were the first to include
it. That one deserves a lot more attention.
What might explain declines among
young people?
FU: We need more studies to tell us why. But for
young people, computer games, increasing social
media use, video games—something is replacing
that time. During that period from 2009 to 2018,
different types of social media emerged. This is
always evolving, especially for younger people.
HERBENICK: We don’t expect there to be one
explanation or one driver in these decreases. We
fully expect that there are multiple things going on
for different age groups, different partnership sta-
tus, different genders. You don’t need those indi-
vidual pieces to explain a big part of a notable
decrease, but ... each one [might] explain a per-
centage point or two.
Is there any contribution from increases
in people expressing an asexual identity?
HERBENICK: We don’t know why more people are
identifying as asexual, but I do think more people
are aware of it as a valid identity. Even compared
with when I started teaching human sexuality in
2003, I routinely had one student in my class who
might identify as asexual. Now I have three or four.
That’s striking to me. I love that young people are
aware of so many different ways to put into words
how they feel about themselves. For many of them,
they feel that it’s okay to opt out of sex.
In your paper, you bring up increases in
“rough sex” as potentially contributing to
declines. Can you explain what you mean
by rough sex, and how it could be playing
a role in these changes?
HERBENICK: Especially for those 18 to 29 years
old, there have been increases in what many peo-
ple call rough sex behaviors. Limited research sug-
gests that an earlier idea of this was what I would
consider fairly vanilla rough sex: pulling hair, a lit-
tle light spanking. What we see now in studies of
thousands of randomly sampled college students is
choking or strangling during sex. The behavior
seems to be a majority behavior for college-age stu-
dents. For many people, it’s consensual and want-
ed and asked for, but it’s also scary to many people,
even if they learn to enjoy it or want it. It’s a major
Emily Willingham is a science writer and author of Phallacy:
Life Lessons from the Animal Penis (Avery, Penguin Publishing
Group, 2020) and The Tailored Brain: From Ketamine, to Keto,
to Companionship: A User's Guide to Feeling Better and Thinking
Smarter (Basic Books, 2021).
