In the battle of the sexes, there’s one fight that never seems to die: who bears more pain? Childbirth is pretty much the gold standard of “this hurts” in everyday conversation – but ask someone with testicles, and they may well think that a swift kick in the balls simply must hurt more. Heck, even thinking about it has probably made one or two of you cross your legs in sympathy pain.

So, which is it? Which set of reproductive organs causes the most anguish? The uterus, the testicles – or some secret third option?

Getting kicked in the balls: the evidence

“It may not have happened to you yet,” begins WebMD, ominously. “But you've probably seen, or at least heard, that taking a hit in the balls – testicles to be exact – does more than knock the wind out of you.”

“Getting hit in the testicles can double you over in pain. It can make you feel sick, even vomit,” it continues. “And if you're hit hard enough, it can send you to the hospital.”

And not only will getting kicked in the ‘nads hurt between your legs, it’ll likely be felt all the way up your belly, too. That’s because your testicles originally developed up in your abdomen, before dropping to the scrotum shortly before or after birth – and they took a bunch of nerves and tissues with them when they went.

But why should such a small (sorry dudes) area be the cause of such a lot of pain? Well, it’s a two-part answer, but in essence: the balls are pretty much perfectly designed to inflict as much suffering as possible to their owners.

Firstly, there’s the simple fact that the testicles are a part of your genitalia. They’re used for sex and reproduction, in other words – and it’s for that reason that evolution has shoved a whole buttload of nerve endings in there.

“At its most basic level, you feel pain because of receptors and nerves,” Nathan Starke, urologist and Director of the Men’s Health Clinic at Houston Methodist hospital, told Inverse in 2018. “And the reason, from an evolutionary standpoint, why it hurts so much to get hit in the testicles is that they are the key to producing sperm.”

Simply put, your body has to make it hurt, because otherwise you wouldn’t bother protecting them from stray footballs or irate ex-lovers. And you really do have to protect them, because here’s the kicker, no pun intended: your gonads are naturally pretty ridiculously undefended.

“It is almost unthinkable to ask why ovaries do not descend during embryological development and emerge outside the female’s body cavity in a thin, unprotected sack,” noted a paper published in 2009 in the journal Evolutionary Psychology. “Because of vulnerability to damage, insult, and temperature variation, unprotected ovaries located outside the body cavity would be… [a] serious reproductive disadvantage.”

“The same reasoning applies with equal force to the testicles,” the authors wrote. And yet, for various reasons – mostly revolving around the need for sperm to be kept cool until, shall we say, go-time – the balls insist on hanging outside the body, tempting fate.

It doesn’t have to be that way – elephants, for example, keep their testicles inside their body, next to their kidneys. But in humans, not only did we decide to keep ‘em dangly, we went ahead and became bipedal, too, thus making their position even more precarious.

In total, then, we have an organ that’s naturally sensitive, located in a thin sac outside of the body, and “protected” by, at most, a floppy length of hose and some tighty-whiteys. Evolution really had it in for these boys, didn’t she?

Kicked in the balls: the verdict

It seems clear that getting a swift punt in the peppers seems tailor-made to cause as much pain as possible. Best case? You should feel better in about an hour. Worst case? Full-on death by ballache.

Giving birth: the evidence

It seems silly to try to explain why childbirth might hurt. It’s a process designed to force one human out of another, through a pipe whose baseline width is only a little over 3 centimeters (1.2 inches), and it has historically killed something like one in 25 of our foremothers.

But what’s strange is that not every species suffers like this. Humans take, on average, nine hours to give birth the first time they do it – longer than a working day, and something like 30 times as long as, say, a horse. Even compared to our closest relatives in the animal kingdom, the great apes, our labors are notably painful and complex; humans are the only animal that requires help to give birth, and for all our modern technology and hygiene, we still suffer much higher rates of maternal and neonatal deaths in childbirth than our wild cousins.

“Pound for pound, given maternal size, we have the longest pregnancies [of the primates], we have the biggest babies and the biggest brains,” Holly Dunsworth, a bioanthropologist at the University of Rhode Island, told Discover Magazine in 2022. “[W]e take a lot out of mama during pregnancy and she births a great, big, gargantuan baby.” 

Why? Well, that’s a good question. While scientists quibble over precisely what weighting to give each of them, it mostly comes down to two factors: our big old brains, and our upright posture. It’s called the “obstetric dilemma” – the evolutionary push-and-pull between being able to walk and run well, and being smart.

The hypothesis is not universally accepted – human hips could be much wider than they are without impeding our ability to walk. But they don’t have to be, is the thing, and evolution is lazy: “What always comes next is, ‘then why doesn’t the pelvis get wider to make childbirth easier?’ And my answer is always, ‘Because it’s good enough. Witness over seven billion humans on the planet’,” Dunsworth explained during a presentation on her work.

The result? Hours and hours of painful labor and delivery, during which your muscles will contract uncontrollably, your cervix and vagina will be stretched to their breaking point, your bones will literally be shoved out of the way to make room for a moving baby, and there’s a genuine chance that you might end up ripping a hole in yourself from your vagina all the way into your anus.

“A labor contraction is just one big muscle cramp, as the entire uterus contracts,” Bart Putterman, an OB-GYN at Texas Children's Pavilion for Women in Houston, told Parents. “And you may perceive that discomfort anywhere that the muscle is contracting.” 

Well, discomfort is putting it mildly: “Some people have contractions that make them double over in pain,” he admits. “You might feel tightening and cramping, along with a backache… It may be because of the position of the baby, or sometimes it's just the way the [laboring person] perceives pain.”

Which brings up another important part of the experience: the psychological aspect. Sure, being kicked in the balls isn’t nice, but neither does it last for hours or even days on end, get progressively worse over time, exhaust your body and mind, or, frankly, taunt you for nine months beforehand. Nearly two-thirds of US women report a pathological fear of giving birth – it’s so common as to have a name: tokophobia – and with fair reason, really, since about 33 per 100,000 of them will die because of it (and no, that number is not getting better.)

Even after giving birth, the pain isn’t over. If you’ve ever seen one of those donut-shaped cushions and thought “huh, who’s using them?” the answer is, in a lot of cases, people who have just given birth. Even if you didn’t tear up your vagina and need stitches in what is one of the most sensitive places on the human body, it’s still recovering from an incredible ordeal, and soreness is to be expected. Meanwhile, those contractions are still going, for some goddamn reason – well, okay, it’s to stop you from dying from excessive blood loss and to get your uterus back to its regular, non-increased-in-volume-by-500-times size, but that doesn’t mean they don’t rankle. Wasn’t this supposed to be over already??

Giving birth: the verdict

It’s literally hours of pushing a human being out of your genitalia. The only way it could be worse is if you were a hyena.

And the winner is…

Look. The problem with pain is, it’s subjective – what’s torture for one person may be a tickle for another. Testes owners may point at mothers-of-four and conclude that giving birth can’t be that painful, really, if you agreed to do it multiple times, but to that we need only reply: ball-busting kink.

Luckily, there’s a cop-out answer that is guaranteed to disappoint everyone: it’s a tie. And hey, at least we can all be thankful it’s not kidney stones.