drunkard's walk

the alkaloids a plant makes for defense
were not designed to mess with mammals' minds
receptors that light up are accidents
but fortunes can be made from such chance finds
small-molecule potential space is vast
and screening for a drug's not without cost
what's done responsibly can't be done fast
and even so, a weak lead may go lost
what Darwin's optimized a billion years
a curandero greets as the gods' gift
intoxicants go way past wines and beers
to give our ideation a quick lift
no barrier divides the nose from brain
impeding instant uptake of cocaine