Where does our food come from?

James Wong

There’s been quite a bit of discussion in the Twittersphere in recent weeks that caught my attention, about the sources and origins of our food, in which botanist, science writer, and broadcaster James Wong (@Botanygeek) has been a lively participant (expertly educating, and oftentimes correcting misinformation that surfaces all too frequently on Twitter).

So where does our food come from? No, I’m not referring to the local supermarket! Nor the countries where it’s grown and exported to the UK, to land on our supermarket shelves, such as avocados from Peru or French beans (Phaseolus spp.) from Kenya, to mention just a couple of examples.

Rather, I’m talking about the regions of the world where our food crops were first domesticated from wild species [1]. In many farmers’ fields, there is still an enormous diversity of shapes, sizes, and colors, as well as response to different growing conditions or reaction to pests and diseases. Just take the example below of potatoes from Peru, varieties that have been carefully cultivated by generations of farmers in the high Andes.

(L): Farmer varieties of potatoes from Peru; and (R): a potato farmer and her husband from the Province of Cajamarca in the north of Peru proudly holding a prized variety.

These diverse crop varieties and related wild species are the genetic resources or agrobiodiversity (perhaps a term more familiar to most through its regular use in the media) that plant breeders need to enhance agricultural productivity, transferring genes between different varieties or species to keep one step or more ahead of changing climates or increased threat of new strains of plant diseases. Without access to this valuable genetic variation, plant breeders would be challenged indeed to respond appropriately to the many threats in the agricultural environment.

There is an ongoing interdependence among countries for access to genetic resources. Take the potato, for example, with which I am quite familiar. The UK potato crop ultimately depends for its survival on plant breeders being able to access different genes and breed them into new varieties. Where do these genes come from? From from cultivated and wild potatoes in Peru and neighbouring countries. Plant breeders at the James Hutton Institute in Dundee, Scotland, regularly dip into the species conserved in the Commonwealth Potato Collection. This potato example is repeated worldwide for most other crops.

Colin Khoury

In a significant open access article (published in the Proceedings of the Royal Society B in 2016) Colin Khoury (a Birmingham MSc genetic resources graduate) and his co-authors state: Research into the origins of food plants has led to the recognition that specific geographical regions around the world have been of particular importance to the development of agricultural crops . . . We estimate the degree to which countries use crops from regions of diversity other than their own (‘foreign crops’), and quantify changes in this usage over the past 50 years. Countries are highly interconnected with regard to primary regions of diversity of the
crops they cultivate and/or consume.

Colin followed up with a piece on the blog of the Union of Concerned Scientists in 2017, discussing the interdependence of nations: The evidence on countries’ predominant use of foreign crops bolsters the rationale for strengthening international collaboration on conservation of crop diversity and for making the exchange of all agricultural seeds as easy and affordable as possible. Our interdependence also boosts the argument for considering the genetic diversity of globally important food crops as public goods which should be openly available to all, and for respecting the rights of farmers to practice their traditional methods of conservation and exchange, not only in recognition of their historical contributions to the diversity in our food, but also in active support of its further evolution.

Just take a look at this interesting graphic (click to enlarge) that was published in the 2016 paper, and republished in the 2017 blog post. I think many readers of my blog will be surprised when they discover the origins of most of the food plants they take for granted.

Origins and primary regions of diversity of major agricultural crops. Source: Khoury et al. 2016. Proc. R. Soc. B 283(1832): 20160792.

However, the concept of centers of origins and crop diversity is not a new one. It was first formulated by the great Russian geneticist (and ‘father of plant genetic resources’), Nikolai Ivanovich Vavilov (born in 1887). See how his centers coincide with the map above. Vavilov’s ideas have been reworked since his death, but still provide a fundamental foundation for the study and understanding of crop diversity. He was starved to death in one of Stalin’s prisons in 1943.

I. The Tropical Center; II. The East Asiatic Center; III. The Southwest Asiatic Center (c0ntaining [a] the Caucasian Center, [b] the Near East Centre, [c] the Northwestern Indian Center; IV. The Mediterranean Center; V. Abyssinia; VI. The Central American Center (containing [a] the mountains of southern Mexico, [b] the Central American Center, [c] the West Indian islands; and VI. The Andean Center.

One of his great works, Five Continents (a memoir of his many plant collecting expeditions) was republished in 1997 on the occasion of his 110th birthday. It had never appeared during his lifetime.

Vavilov, NI, 1997. Five Continents. International Plant Genetic Resources Institute, Rome, Italy. ISBN: 92-9043-302-7

Then, as I was thinking through these ideas about food origins, I came across the two photos below. At first I couldn’t recall where they had been taken. Then I realized they must have been taken during the drinks reception after the half-day N.I. Vavilov Centenary Symposium, jointly organized by the Linnean Society of London and the Institute of Archaeology of University College London on 26 November 1987 to commemorate Vavilov’s birth. I was one of the speakers.

Top: with Joe Smartt (University of Southampton). Bottom: Chatting with Joe Smartt, with Prof. Jacks Hawkes (University of Birmingham, to my left) with another symposium attendee.

The papers were published in a special edition of the Biological Journal of the Linnean Society in January 1990.

Sadly, all my fellow presenters have since passed away [2].

In the first paper, 1. Preface, Jack Hawkes and David Harris state the following: Vavilov laid the foundations of modern plant breeding, stressing the importance of the wide range of genetic diversity in our ancient crops and in related wild species—a diversity that before his time had barely been used or understood by breeders . . . Not only this—the whole movement of crop genetic resources conservation as a necessary prerequisite for the new more resistant and productive varieties needed now and in the future can be clearly traced back to Vavilov’s seminal ideas . . . Vavilov’s theoretical studies on crop plant origins and evolution under domestication, the areas in which crops evolved and the parallelism in their diversity in particular regions also possess clear practical implications, as well as linking into prehistory and the beginnings of agriculture.

In the second paper, Jack Hawkes discussed the impact of Vavilov’s work. He had met the great man on his visit to the Soviet Union in 1938.

Geographer David Harris discussed the origins of agriculture and how Vavilov’s studies on the centers of origin influenced the work of many other scholars. Yet he concluded that with the discovery of new evidence about the origins of agriculture, Vavilov’s concept as such had outlived its usefulness.

I was privileged to be asked to contribute to this symposium, standing alongside three colleagues: Joe Smartt, Jack Hawkes, and Trevor Williams who had encouraged me to enter the world of genetic resources and supervised my research, and mentored me at various stages of my career.

Professor Hugh Bunting had been the external examiner to the Birmingham MSc Course on genetic resources when I presented my dissertation on lentils in September 1971. There was a link to Vavilov there, because his second wife, Elena Barulina, wrote the first monograph on lentils.

My own paper discussed how homologous variation among potato species was evident when looking for resistance to pests and diseases.

I only met Gordon Hillman on one occasion at this symposium. He made very significant contributions to our understanding of early farming systems and the domestication of cereals in the Near East.

In his paper, Hugh Bunting discussed how Vavilov promoted the inclusion of physiological and biochemical features alongside descriptions of morphology to understand how plants were adapted to their environments. The examples used were groundnuts and sorghum, crops which Bunting had studied in Africa over many years.

In the final paper, Trevor Williams (who was Director of the International Board of Plant Genetic Resources, IBPGR, the forerunner of the International Plant Genetic Resources Institute, IPGRI, and Bioversity International) discussed how IBPGR’s program of collecting and conserving crop varieties and wild species worldwide had been guided by Vavilov’s ideas on centers of diversity.

As you can see, there’s more to this story of our food and its origins than perhaps meets the eye initially. It’s a story that I have followed for the past 50 years since I first set out on my career conserving and using plant genetic resources.

[1] Avocados originated in Central America, and French beans come from South America.

[2] I’ve not been able to find any further information about Stuart Davies, co-author with Gordon Hillman, since his retirement from Cardiff University.

This book (ISBN: 90-220-0785-5), by Anton Zeven and Jan de Wet, published by the Centre for Agricultural Publishing and Documentation in Wageningen in 1982 is an excellent source of information about the crop and wild species found in the centers of diversity.

It was a revised second edition of: Zeven AC and PM Zhukovsky, 1975. Dictionary of cultivated plants and their centres of diversity.

Zhukovsky was a follower of Vavilov and further developed the idea of centers of origin and diversity.