How Did Poppies Get Into the Opium Business Anyway?BloombergOpinion
(Bloomberg Opinion) -- The future fates of thousands of people pivoted more than 7 million years ago with a molecular fluke inside a flowering plant. The DNA was supposed to copy itself once, but instead did it twice, leaving the descendants with a duplicate set of genes. This appears to have represented an essential step in the ability of the opium poppy to produce some of the most useful, enticing and deadly substances humanity would ever come across.
Today, most deaths from opioid addiction come from synthetic versions of these compounds like fentanyl. But it’s unlikely humanity could have invented heroin in the modern era if plants hadn’t shown what was possible.
York University biologist Ian Graham has been studying the evolution of opium poppies and other medicinal plants for over a decade. He said he and a group of colleagues from England and China were able to retrace the fateful molecular error, and its prehistoric timing, by sequencing the genome of the opium poppy and comparing it to genomes of related plants. The results were published this week in the journal Science.
It was only at the turn of this century that scientists read the first genetic sequence — from humans. Since then, the process got cheaper and faster, and now they’ve sequenced thousands of organisms, from cats to chickens to watermelons. That’s led to a new understanding of the kinds of genetic errors and shuffles that mattered in shaping the living world today.
They’ve found that in plants, the whole genome can be duplicated pretty often, and when this happens, it gives the plants with the extra genes an opportunity to diversify. All kinds of mutations can crop up in an extra copy that, in a plant with only one copy, would be fatal or deleterious.
Scientists can also use the sequences as a molecular clock, using the number of individual letter DNA typos (which occur at a regular rate) to estimate how long ago related species diverged, or, in cases like this, how long ago the DNA of the opium poppy duplicated itself. The making of natural opioids — codeine and morphine — is a multi-step process, or pathway, in the plant, and each step required different sets of evolutionary changes. There were other critical changes that happened before the duplication, including the fusion of several genes into one.
Morphine and codeine are the end products of all these changes, and they, as well as some of the intermediate compounds produced by the poppies’ precursors, probably gave the plants making them an advantage. But how these compounds benefited the plant isn’t revealed in the genome. What we do know is plants produce most of the chemical diversity on this planet. Some compounds may discourage or sicken animals that try to eat them. Others might attract insects needed for pollination or birds that can spread the seeds.
It didn’t take humans long to discover opium poppies. There’s evidence that people used them back in the stone age. But why should a chemical made by a plant have just the right shape to lodge into the pain receptors in the human brain?
It’s a question author Michael Pollan contemplated in his book “The Botany of Desire.” There, he devotes a chapter to another medicinal plant — marijuana, which also manufactures a substance that seems ready-made for human brain receptors. It may be the kind of coincidence that becomes likely when you consider how many plants there are, and how many different chemical compounds they produce, and how many years human beings have been experimenting with these to find out which ones happen to mesh with our brains and bodies.
While most of the recent news about opioids has been bad, they continue to help people who would otherwise suffer intolerable pain. Knowing how plants first made them might help biologists supply these compounds cheaply, and perhaps improve upon them — to make them more useful, and less deadly.
This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.
Faye Flam is a Bloomberg Opinion columnist. She has written for the Economist, the New York Times, the Washington Post, Psychology Today, Science and other publications. She has a degree in geophysics from the California Institute of Technology.
©2018 Bloomberg L.P.