For whatever reason, human beings associate certain animals with pregnancy.

Birds, bees, storks.

But last century, no animal was more central to family planning than Xenopus Lillis, the African clawed frog.

The association between babies and frogs began with a man with the

fanciful name of Lancelot Hogben, who stumbled upon a secret, that frogs could predict

pregnancy. It sounds like something out of a fairy tale, but it had nothing to do with princess's

kissing toads. It was straight physiology.

If you expose frogs to urine, the frogs can reliably predict who was pregnant and who was not.

This was the first fast, cheap, widespread pregnancy test in history and it empowered women's health in unprecedented ways.

But the legacy of Hog Ben's frog test was not wholly benign.

For all the good the test did for women,

it's also been blamed for the worst pandemic that scientists have ever seen.

From the Science History Institute, this is Sam Keene and the Disappearing Spoon,

a topsy, turvy, sciencey history podcast, where footnotes become the real story.

Doctors in ancient Egypt developed the first known pregnancy test around 1400 BC.

In it, women urinated on a mix of barley and wheat seeds.

If the baby was male, the barley supposedly sprouted.

If female, the wheat sprouted.

If neither sprouted, she was not pregnant.

Now, this test does not work as advertised.

It cannot distinguish male fetuses from female ones.

But in the 1960s, scientists did determine that, in 70% of pregnancies, a woman's urine did help seed sprout and promote growth, perhaps due to

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