The experiments, frankly, were failing.

It was the 1950s in New York State.

Some biochemists there were studying parasitic worms,

some of the nastiest critters on Earth,

the bane of people, pets, and livestock worldwide.

So the biochemists started testing an anti-worm drug in mice.

The drug's technical name was Win-18446.

Unfortunately, Win-18446 flopped at killing worms.

It just wasn't effective.

To their disappointment, the scientists realized the experiment was a bust.

Or was it?

As often happens in research, the scientists noticed something else.

A little quirk that ended up being even more intriguing than their original goal.

The quirk was this.

In between getting injected with drugs,

lab mice back then were free to live their lives and do mousey things.

Nibble cheese, groom themselves, burrow, and also have sex.

And of course, biology being biology, some lab mice would inevitably get pregnant.

But the thing was, none of the mice taking Win-18446 got knocked up.

This was unusual, so the researchers looked a bit closer at the females.

The females seemed normal, so the scientists switched focus to the males.

And here came the surprise.

...