It isn't every day you see the Tao Te Ching as reference #1 for a Nature paper. Here is the relevant chapter: https://www.egreenway.com/taoism/ttclz78.htm

I love when papers go out of there way to have a really old citation, sorta a secret competition of who can find the oldest relevant document.

It isn't so much a race to find the oldest document, but rather a way to acknowledge the ancient giants on whose shoulders we stand.

Citing all the way back to Laozi is kind of a power-move, though. Done wrong, it seems silly and contrived. In this Nature article, it was well done and gave a broad facet of humanity to an otherwise-technical work.