Reddit reviews Plants and the Human Brain

I have a little something to add to this.

There is this book called Plants and the Human Brain. It's pretty technical and arduous so I only read about half of it. But the take home message of this book is that there's nothing righteous about plants. Plants don't make the compounds that they make for our benefit, but for their own reproductive purposes.

Basically plants and insects co-evolved for a long long time - much longer than we have been around. So during this time there were no mammals, no birds, just insects. If you are a plant that uses flowers to reproduce you need to be able to manipulate insects to do the pollinating for you. At the same time you want your leaves not to be eaten by insects. So you make chemicals that you can use on insects. On one hand you want chemicals that deter insects, like poisons, for use where you don't want to be eaten. On the other hand you want chemicals that attract or reward insects for doing your bidding, like nectar or scents.

The reason why all these drugs that plants produce work on us is only because we have similar nervous systems to insects. They were never intended to be used on us, we just haven't been around long enough for plants to evolve the mechanisms. Plants and insects go back much further in time though, and it's our distant relationship to insects that gives us the similarities in nervous systems.

For your example of the orange tree, it's not making calcium for our bones. The orange tree doesn't care about our bones, it's doing it for its own survival and reproduction. So when we benefit from plants, that's just lucky for us.

The book is Plants and the Human Brain by David O Kennedy

https://www.amazon.com/Plants-Human-Brain-David-Kennedy/dp/019991401X