The Botany of Desire: A Plant's-Eye View of the World

by Michael Pollan

The scientists I spoke to were unanimous in citing short-term memory loss as one of the key neurological effects of the cannabinoids. In their own way, so were the “poets” who tried to describe the experience of cannabis intoxication. All talk about the difficulty of reconstructing what happened mere seconds ago and what a Herculean challenge it becomes to follow the thread of a conversation (or a passage of prose) when one’s short-term memory isn’t operating normally. Yet the scientists said that the THC in cannabis is only mimicking the actions of the brain’s own cannabinoids. What a curious thing this is for a brain to do, to manufacture a chemical that interferes with its own ability to make memories—and not just memories of pain, either. So I e-mailed Raphael Mechoulam to ask him why he thought the brain might secrete a chemical that has such an undesirable effect. Don’t be so sure that forgetting is undesirable, he suggested. “Do you really want to remember all the faces you saw on the New York City subway this morning?” Mechoulam’s somewhat oblique comment helped me begin to appreciate that forgetting is vastly underrated as a mental operation—indeed, that it is a mental operation, rather than, as I’d always assumed, strictly the breakdown of one. Yes, forgetting can be a curse, especially as we age. But forgetting is also one of the more important things healthy brains do, almost as important as remembering. Think how quickly the sheer volume and multiplicity of se...