Pretty cool result with lots of experimental evidence.

Another purely speculative example - Geosmin is the human-recognizable indicator of rain, and given how intensely sensitive we are to this molecule, I wouldn't be surprised if many ecosystem participants also sniff for this molecule.

Summary: biology uses chemical signalling. Signals can be used for multiple purposes by different critters.

I'd say dihydrogen monoxide is pretty obviously a keystone chemical.

Its crazy how they put it in everything. The EPA and the FDA should work together to ban it, but good luck approving that with our current administration.