Greatest invention/discovery in the last 500 years?

[Lumpy]

@PhillyGuy

If the pill turns out to be the most impactful invention, I think it will be because it leads to below-replacement fertility, putting humanity on a spiral towards extinction.

A less impactful possibility is that it will cause the demise not of the species as a whole, but only of modern people who use such birth control, with humanity in the future consisting of insular religious groups having high birth rates, like the Amish, Hutterites, and Hasidic Jews.

Or women who have a deep-seated biologically based craving for babies. I raised this topic in an old thread Is birth control ultimately self-defeating?