Boxer shorts were introduced in the 1920s
for, well, boxers.
This underwear was loose around the legs,
giving boxers the freedom that they needed
to move around the ring.
Then, about a decade later,
briefs came into the world,
offering a sleeker, tighter-fitting option
and sparking a now-classic question.
Boxers or briefs?
And as it turns out, there may be a clear winner after all.
You heard that right,
wearing tight underwear can lower your sperm count.
Turns out if underwear is too tight,
it pushes the testicles closer to the body,
increasing their temperature in the process,
and that's bad news for the sperm inside.
You see, a man's sperm production is at its best
when his testicles are cooler
than his core body temperature.
Two to 4 degrees Celsius cooler, to be exact.
That's why the testes hang down
away from the body
for most mammals.
So when you wear tight underwear,
the resulting increase in temperature can damage the sperm
and potentially your fertility as well.
Scientists have been studying the link
between body heat and fertility for years.
Several studies show that men who work under hot conditions,
like bakers and ceramic oven operators,
are more likely to have fertility issues
than men who work cooler jobs.
But ovens, of course,
are much, much warmer than the human body.
So it wasn't until recently
that researchers discovered that, yes,
even small increases in temperature
from wearing tight underwear can cause problems.
In 2018, Harvard researchers released
the largest study on the subject to date.
They analyzed 656 men
seeking treatment at fertility centers
and recorded their daily underwear preference,
boxers or nonboxers, like briefs and Jockeys.
Sure enough, men who wore boxers had 33% more mobile sperm.
You know, the kind that can swim
and successfully fertilize an egg.
They also just had more sperm in general,
about 25% more in their collected samples.
But researchers also found something they weren't expecting.
Men in the nonboxers group had higher levels
of something called a follicle-stimulating hormone, or FSH.
FSH is released by the pituitary gland
to help boost sperm production in the testes.
So researchers think that an increase in FSH levels
could be the body's way of compensating
for low sperm production.
And while both groups of men
still had plenty of sperm needed to conceive a child,
researchers found that tight underwear
could jeopardize the fertility of men
who already suffer from low sperm counts.
Luckily, young, healthy men
tend to produce sperm continuously.
So it's possible to reverse damage
caused by wearing tight underwear
simply by switching to a less confining option.