everything on the Earth has a purpose, every disease an herb to cure it, and every person a mission. This is the Indian theory of existence.

If I'd been born a hundred years ago I'd probably have thought this 'Red Indian' an inferior, less evolved, human being than white Europeans (and especially British) like me. I would also have regarded working class people as inferior, and upper class people as superior to middle-class me.

Growing up in the late 20th century I came across reverse snobbery: the idea that working class people are more authentically human than us effete middle classes. And these days there's a vein of inverse racism that credits Native Americans like Ms Quintasket – and others of what my grandparents would have regarded as Inferior Races – with Superior Wisdom to ours.

And it's just as much bollocks as straightforward racism and class prejudice.

There is, no doubt, a lot that Christal knew about the world she lived in that I don't, and wouldn't have if I were alive when she was. But there is a lot that she – and my compatriots 100 years ago – didn't know, that we do now.

Thanks in no small measure to Richard Dawkin's "The Selfish Gene" far more of us now know what Darwin, Wallace and others were realising a few decades before Christal Quintasket was born: that the purpose of every living thing on the earth is to reproduce offspring bearing its genes as widely and vigorously as possible. For most plants an important part of staying alive and reproducing is not to get eaten by animals, and one way to do this is to poison those that try. To this end plants have evolved a variety of toxins which affect the animals that would have them for lunch, according to their predators' particular biochemistries.

Animals differ biologically and a substance toxic to one particular predator may have no effect on others; it may even be beneficial to some, but as long as it doesn't turn the beneficiary into a predator there's no reason for the plant to have evolved out such side-effects. So we find there are plants that produce substances we have found to be medicinal (not to mention recreational!) to us. Nowadays we understand that this is just a quirk of nature but people would once have assumed that such benefits must be the result of divine intention. In our own culture the Bible has God telling His people that He has given them "every plant yielding seed that is on the face of all the earth, and every tree with seed in its fruit". Native Americans of Ms Quintasket's time probably had no more clue that plants' medicinal benefits were simply a happy accident of nature than most of their European contemporaries and would have put them down to similar deist or theist benevolence. Ascribing Superior Wisdom to her words because she was a Native American is as racist as ascribing inferior intelligence to her for the same reason. She was just a human being, genetically practically indistinguishable from you and me. She was part of a culture different from ours and lived at a time when we didn't know much about how life on our planet came about and evolves. And her utterances on medicine and healing are as valid today as my grandmother's were.

Jeffrey Rowland cartoon about Dream Catchers