Book Talk

How Little Seeds Shaped Human History in Big Ways

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The variety of rain forest seeds and seed pods can be dazzling. “For the plant, it’s an evolutionary imperative to not only make seeds but to defend and disperse them,” the author says.

Thor Hanson, author of The Triumph of Seeds was doing fieldwork in Central America when he became fascinated by the seeds of a giant rainforest tree known as the almendro. Hard as rock, impervious to hammer blows or chisels, they set him to wondering how seeds are dispersed and how they have shaped human history.

Speaking from his home in Washington state, where he is a conservation biologist, he explains how grains and revolution often go hand in hand; why Ugandans throw millet over newly married couples; why seeds are the frackers’ best friends; and why the future of seeds is such a hot button issue.

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The book opens with you trying to smash a seed with a hammer. Were you having a nervous breakdown, or what?

[Laughs] I had chosen to study this fascinating rainforest tree in Central America, the almendro which is a keystone species there. It produces fruit that is like a single-seeded pod. Inside is this incredibly tough seed. The fruits are dispersed by bats, which pluck them and take them to a feeding roost, eat off this thin bit of flesh, then drop the seeds. Rodents and other creatures, like agoutis, then stash the seeds like squirrels.

I’d collected a bunch of seeds and brought them back to my office in the university, but realized I couldn’t get the bloody things open. First, I tried with a chisel and a hammer. Eventually I was trying to drop heavy objects on the seed. But it was just this impenetrable, hard shell that wouldn’t show a scratch even when you whacked it.

Why would a seed be so hard to open? For the plant, it’s an evolutionary imperative to not only make seeds but to defend and disperse them. So, in the case of the almendro, the seed has developed this terrifically tough seed coat that is almost impossible for rodents to gnaw through. Seed defences show a marvellous range of adaptations, from something as intuitive as a hard shell to the range of chemicals seeds use to defend themselves.

What inspired you to write this book? You had a little helper, didn’t you?

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Acorns hang on a white oak in Sewanee, Tennessee. The seeds germinate slowly after settling into the earth.

I have a long interest in seeds. I have a masters degree in botany and my doctoral work was done, in part, studying the seeds of this rainforest tree. The strategies that plants use to reproduce and disperse themselves are very interesting to me intellectually. But I had a helper in inspiring me to do the book.

When I was deciding whether to write, our young son was a toddler and had, and continues to have, an obsession with seeds, or “heeds” as he called them at that time. He could not pronounce his s’s, so he decided he would replace S sounds with things he could say, like a hard h. Spiders become hiders, cell phones turned into hell phones and seeds turned into heeds. Day after day he would open up pieces of fruit, take the seeds out and shout “heed!” Eventually, that tipped the balance. I heeded the seeds [laughs] and decided that these things were, indeed, worthy of a book.

George Bernard Shaw, the British playwright, referred to the “fierce energy of an acorn.” What did he mean?

I think he was inspired by the promise of seeds. There’s a deep metaphor in the idea that something tiny can transform itself into something immense. His famous quotation is that you plant an acorn and it explodes into a giant oak, but if you plant a sheep nothing happens but decay. And I think the metaphor of seed is deeply ingrained in our culture. It’s why seeds are used in wedding ceremonies, like throwing rice over a bride and groom. The Romans threw wheat, Ugandans throw millet. In other parts of the world it’s almonds or even cotton. It’s this idea of fertility and rebirth, but also the practical aspect of sharing agricultural knowledge.

Seeds lie at the heart of the debate raging around genetic modification or GMO’s.

Darwin became fascinated in later life with seed dispersal. How did that connect with the theory of evolution?

Darwin was fascinated by how plants and animals were distributed around the world. That question was a natural one for him during the voyage of The Beagle, where they cross so many different life zones in South America, then across the Pacific and down to Australia. Seeing the patterns of plants and animals, he of course asked himself: Why are these things where they are? How did they get there? That was one of his first questions in the Galapagos.

He was mostly interested in animals and geology. He collected plants mostly as a favor to a mentor back in England named Henslow, who had been his botany professor. In terms of the birds of the Galapagos, he recognized an association with South America, and began wondering how those plants were dispersed and how they could cross hundreds of miles from mainland South America.

Back in England, he began a series of experiments studying how seeds survive in saltwater and what happens when a seed lands in the soil. This really opened his mind to botany, and later in life he wrote several books devoted to botanical themes.

Grass seed is something most of us use to patch the lawn at this time of the year. But you say it “changed the course of human history.” How?

The seeds of grasses provide us with a huge component of the calories in our diet. You could argue that nothing is more important to the human endeavor than the growing of grass. Staple crops around the world, like rice, oats, barley, millet or sorghum, are for the most part members of the grass family. They produce the seeds that give us the porridges, flour and bread we eat. They are literally the staff of life.

Until quite recently, individual strains of crops were grown at the village or family level. When people got married they joined families. But they also united agricultural traditions. That idea is ingrained in our culture. Ingrained literally means “in the seeds.” The word culture comes from the Latin, cultura, meaning the care bestowed upon plants.

Grains also have a long connection with revolution. If you look through the history of revolutions—from the fall of the Roman Empire to the French Revolution—very often those times were preceded by drought or periods of grain shortage.

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Wind is one means of seed dispersal. These are cotton grass seed heads.

In our own times, the Arab Spring broke out following massive droughts in Russia and Europe. Wheat was in short supply in Egypt, one of the world’s great importers of wheat. Prices had skyrocketed and there were food riots there and in Tunisia. It’s telling that Algeria did not have the same sort of revolution. What did they do that year? They invested billions of dollars in wheat imports to keep the people well fed.

Fracking is a new technology that has caught the world’s attention. I was surprised to discover that it would not be possible without seeds.

People would never associate the oil industry with seeds. But a key component of hydraulic fracturing fluid, the fluid that’s pumped into wells being fracked, is a ground up bean from northern India called guar. Guar beans are incredibly good at holding water, because this is a species that evolved in a very dry, desert-like climate. As a result, it works as a wonderful thickener, and is the key thickening component in fracking fluid. Prices of guar beans went up 1,000 to 1,500 percent in a couple of years after the fracking boom began. Farmers in northern India, who were feeding this stuff to their livestock, were suddenly selling it for top dollar and saw a huge increase in their standard of living.

Gregor Mendel, the father of modern genetics, famously spent years crossbreeding peas. You tried to replicate his feat, didn’t you?

I was really interested that the father of modern genetics made his breakthrough studying seeds. He could’ve studied all sorts of things, but what really provided the breakthrough was his study of peas. I think that speaks again to how closely tied we are to seeds culturally. Mendel’s experiments went on for eight years, so I decided to try and replicate a small part of them.

I got some old varieties of wrinkled and smooth peas and bred them in the way Mendel had for a couple of generations, until I could see the dominant and recessive traits expressed in the way he did. Because of his studies of peas, Mendel was able to determine that traits are passed on as discrete units, as genes, even though he didn’t yet have the word gene.

The Seed Savers organisation offers people a way of connecting with their family past. How does it work?

Seed Savers is a wonderful group that was founded in the 1970s by a married couple who began with just a small advertisement, trying to collect different varieties of vegetable seed and get people to share them. Varieties of vegetables produced over the first ten thousand years of our agricultural system have greatly declined in the last hundred years. We’ve become more and more dependent on a few commercial varieties of crops. As a result, there’s been a great loss of diversity in everything from tomatoes to cabbages to corn. The Seed Savers work to keep those varieties alive in people’s gardens.

Seeds can also be used as weapons. Tell us about what you call “the most famous assassination of the Cold War.”

It is an incredible story. There was a murder on the Waterloo Bridge in London in 1978. A Bulgarian dissident, George Markov, was stabbed in the back of the leg with the tip of an umbrella. At first, people couldn’t figure out how he had died. It seemed he may have been poisoned but no one could find a trace of it until another dissident was attacked in a similar fashion in Paris. That person survived and they were able to extract a tiny pellet from his back.

They quickly narrowed the field down to a seed poison, particularly ricin, which is extracted from the seeds of the castor bean. It kills people so quickly that the body rarely has a chance to even produce antibodies to fight the poison. As a result, ricin continues to be used in terror attacks.

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The soybean, cradled in the hands of a Nebraska farmer, is an edible legume with a variety of uses.

Your books ends with what you call “the controversy raging about the future of seeds.” What’s happening?

Seeds lie at the heart of the debate raging around genetic modification or GMO’s. When I read those stories I have to ask myself: Why seeds? Genetic labs are producing everything from featherless chickens to goats that produce spider silk. So it’s fascinating that seeds are the thing people feel they must rally around and defend. I think that speaks to the deep cultural connection we have with seeds.

There’s a concern about changing the genomes of seeds and about patenting seeds, so that farmers can no longer save their own seeds or do their own plant breeding but become tied to a few patented varieties of engineered seeds. But genetic modification has simply joined a long list of technologies we’ve invented, which we struggle to make peace with, from nuclear power to drones. We invent these amazing things and then have to decide how we’re going to use them.

This interview has been edited and condensed.

Simon Worrall curates Book Talk. Follow him on Twitter or at

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