This weekend, I have just finished reading 'Les goûts et couleurs du monde' by Marc-André Sélosse

A fascinating journey into the world of this family of molecules, which plays an essential role in living organisms. While tannins play an essential role in wine, through their antiseptic and antioxidant properties, tannins are indispensable to plants. They enable them to strengthen their structure and rise in search of light, and to protect themselves against predators (for whom tannins in high doses are toxic). In short, tannins are indispensable to the plant kingdom.