Some of the most memorable scientific moments do not happen in spotless labs filled with beakers and white coats. They happen in places you would never expect, like inside a humming MRI scanner, with two volunteers trying to stay perfectly still while doing something deeply human. The story sounds like a dare, but it ended up reshaping how researchers talk about anatomy and arousal. And it all started with a couple who agreed to take part in an experiment that was as awkward as it was groundbreaking.
Back in 1991, Dutch woman Ida Sabelis and her partner Jupp said yes to an unusual request from scientist Menko Victor “Pek” van Andel. The goal was simple on paper and wild in practice, to capture images of what happens inside the body during sex. At the time, this kind of visualization had not been done, at least not in a way that produced clear internal images. Years later, the findings were published in the British Medical Journal, turning their private moment into a lasting scientific reference point.
The scan results revealed details that surprised many people, especially those who assumed the body behaves in straightforward ways. In the missionary position, the penis was shown to curve in a shape often compared to a boomerang, with a significant portion of its length made up of the internal root. The images also offered a clearer look at changes in the female reproductive organs during arousal, showing how the uterus and vaginal walls shift. It was the kind of evidence that moved conversations beyond guesswork and diagrams, and into something observable.
Sabelis has since spoken about the experience on the podcast What Was It Like, and she did not pretend it was glamorous. Early MRI machines were slow, which meant holding a position longer than anyone would choose in real life. She recalled being instructed from the control room to stay still, which made the whole thing feel absurd and oddly comedic. The scanner was tight, but she and Jupp were not claustrophobic, so they managed to get through it.
What stands out is how she framed her choice afterward. She described it less as romance and more as a mix of love and performance, with a purpose beyond the moment itself. As someone who has advocated for women’s rights, she saw the experiment as a way to push medical understanding of women’s bodies forward. It is a reminder that progress sometimes comes from people willing to endure discomfort, embarrassment, and a very loud machine for the sake of better knowledge.
Would you ever volunteer for an experiment this unconventional, or do you think some lines should stay uncrossed even in the name of science? Share your thoughts in the comments.
