By LUIGI GUARINO | Director of Science and Programs
No, not my contribution to the debates on Brexit or who should be the next US president. The immigrants I have in mind are plants, not people – though admittedly ones that have been tamed and spread around the world by people.
I tweeted the quip a few days ago by way of summarizing the findings of a paper that a few of us at the Crop Trust have been involved in writing for the past several months, and which has just come out in the Proceedings of the Royal Society B. I have more than 140 characters here, thankfully, so I can explain the results, and what they mean, in a bit more detail.
First, some background. Led by Colin Khoury at CIAT, who actually worked at the Crop Trust a few years ago, with this paper we build on another study that we published a couple of years ago. That earlier paper used the FAO’s huge treasure-trove of yearly national-level food production and consumption data to ask the question: how many crops feed us? The headline answer was: more than used to be the case; but increasingly the same, relatively few ones, no matter where you live. Around the world, our diets are generally getting more diverse, which is good; but also more like each others’, and more dependent of a few “core” crops, which is maybe not so good. You can read that study here. It got quite a lot of attention at the time, even netting Colin a prize.
In the new paper, which is also getting a lot of coverage, Colin and the rest of us decided to dig a bit deeper into the data and break down national diets not by crops, but by the geographic regions where the crops were originally domesticated. So, not what and how many crops feed us, but what regions of the world do so.
We have known for a while now, ever since the pioneering work of the Russian agricultural scientist Nikolai Vavilov a hundred years ago, that different crops were domesticated – plucked from the wild and made to do our bidding on our farms and gardens and orchards – in different parts of the world. Wheat in the Fertile Crescent, maize in what is now Mexico, rice in eastern Asia, and so on. They then spread from those places, carried by the bride for sowing in her new husband’s faraway village or by the tall ship to the other side of the ocean. Some spread more and farther than others, but all retained, and continue to retain, a large part of their diversity where they started out, in their ancestral homes, their so-called centres of origin. Which makes sense, because that is where they have been tended and selected by people the longest, and where they can still naturally exchange genetic material with their wild precursors and other relatives. (And by the way, you can follow our work on crop wild relatives, including their geographic distributions, on the website of our project Adapting Agriculture to Climate Change: Collecting, Protecting, and Preparing Crop Wild Relatives.)
Vavilov and others after him made sure that this diversity would survive and be available to both scientists and farmers into the far future by building genebanks and filling them with seeds from all around the world. The one that he started in Russia is named after him now. Because of the collecting and research work of these pioneers, and their successors, we can assign to each crop in the FAO production and consumption database a region of the world from which it originated. (You can explore all this in the interactive website we prepared to go with the paper.) And we can therefore calculate how much farming systems and diets in a given country depend on crops which were either originally domesticated in what is now that country and its neighbours, or in another region altogether. By locals or by immigrants, in other words.
And that’s where we got the result that I tweeted. On average, around the world, we now grow and ingest over two thirds of our plant-based sustenance from crops that a few generations ago we may not have even known, and whose press-ganging into agriculture in the first place is in large part due to ancient farmers from the other side of the world. And the percentage has been increasing. We are, indeed, mostly – and increasingly – fed by immigrants.
Think of that when you have your next pizza. And thank the farmers in your country who perhaps grew the wheat for the base or the tomatoes for the topping. While you’re at it, consider that real mozzarella is made from buffalo milk, and that animal was domesticated in south Asia.
But also thank the ancient farmers of what we now call the Middle East and Central America. They had the original hunch that something could be made out of some of the totally unprepossessing wild members of the grass and nightshade families that were growing around them, and then indeed made hundreds of different, delicious cultivated varieties out of them.
Now think back to those centres of diversity. Even if you live in one, chances are that a lot of what you eat comes from another. We all need that diversity, including the diversity now found only in genebanks, because for whatever reason farmers have lost it in their fields. That need is arguably greater now than it has ever been, of course, because we have to meet the challenges of climate change, and a bigger and more demanding human population. But Vavilov recognized it a century ago. So let’s thank him too, and his successors down to the present day, breeding crops and tending diversity collections and negotiating treaties. They have all shown us what a bad idea it would be to wall each other off from the agricultural biodiversity of immigrant crops.
The Crop Trust is excited to announce a weekly science blog by Luigi Guarino, Director of Science and Programs at the Crop Trust. Luigi currently co-authors one of the most eminent Twitter accounts and blogs on crop diversity conservation in the world and has written many times for the Crop Trust’s news section in the past. We are happy to see these blogs turn into a more regular series and invite you to check back weekly for his latest posts.