A recent news item has highlighted once again the problems that small farmers face in a world in which the food supply is becoming more and more consolidated in a small number of large corporations at the expense of independent producers. The issues are complex but one that is fundamental is the loss of plant diversity, and particularly the diversity of agriculturally important crops, and the threat that this poses not only to the food supply but also to livelihoods and rural economies.
About 13,000 years ago, humans started to collect seeds from wild plants which were already used in the diet of the nomadic hunter-gatherer and they began to cultivate these plants in a more systematic way. These plants may not have been ideal for systematic agriculture but, over time, through natural genetic mutations, some of the plants will have produced seeds which then gave rise to plants with better characteristics, such as their yield, tolerance to special climatic conditions, improved food quality and so on. By harvesting seeds from the “best” plants for the next year’s sowing, the crop plants would eventually reach a domesticated state where they were no longer able to grow and reproduce without human intervention. This process is very slow and for many of the basic foods consumed is estimated to have taken around 2000 to 4000 years (Jensen et al., Hirst). The variety of plants expanded according to local requirements, and seeds were handed down from generation to generation. With the increase in human interactions, the exchange of ideas and products either through trade or via conquest led to the availability of a wide range of foods, especially in the more affluent parts of the world.
Moving forward to the modern era where plant genetics became better understood, selective breeding programs led to a much increased food supply which enabled rapid population growth, as well as a more varied diet (for those able to afford it). As a trade-off, however, because the selected plants represented just a small fraction of the total wild population, domestication was often accompanied by a reduction of genetic diversity and this has meant that crop plants are in danger of lacking natural defenses to threats from pests and diseases.
There is increasing evidence that crop domestication has profoundly altered interactions between plants, pests such as insects, and the other natural enemies of these pests. Before domestication, the evolution of wild plants and the organisms that depend on them took place at a similar rate and so there was a state of equilibrium. Artificial selection of plants by humans upset this equilibrium and, as a result, domestication has frequently resulted in reduced plant resistance against pests and thereby enabling these pests to develop in an uncontrolled fashion.
The banana is an example of what can happen. In the Western world, the banana is almost exclusively consumed as a dessert fruit and selective breeding produced cultivars with the most desirable characteristics, not only for taste but also for ease of production, transport and storage. Up until the 1950s the main such variety was the Gros Michel banana but a fungal disease wiped out large areas where this banana was cultivated and it became no longer economically viable. The search for an alternative led to the discovery of the Cavendish banana, which now accounts for about half of all bananas consumed world wide and for almost all that are consumed in Europe, North America and China. Now there are fears that the Cavendish banana will also suffer the same fate as the Gros Michel and, since all the plants are essentially clones, there is little of no genetic diversity within them for resistant plants to be developed and such a disease could spread very easily.
In the case of the banana, the existence of a diverse gene pool in other varieties, chiefly in south-east Asia, will likely lead to the development of resistant strains, but for plants where such a gene pool does not exist or is restricted to wild species which are disappearing, or may even be already extinct, there is a danger to the food supply and the lives of those who are dependent on its production.
In recent years, there is an increased awareness that the cultivation of neglected or underutilized species is a viable development strategy with benefits such as mitigated climate risks, enhanced agrobiodiversity and better rural livelihoods. Seed banks of threatened species are now to be found all over the world and, provided they can maintain the proper conditions for long-term seed preservation, they form a line of defense against the loss of plant biodiversity.
A major problem that also needs to be faced, however, is the fact that the types of agricultural products that are now consumed has actually decreased in number over time. For example, in North America, it has been estimated that 3-5000 species of wild plants were once used as food, while today little more than 100 satisfy 90% of the world’s food needs are met by just over 100. Economics of scale play a large part in this trend. Plant products are selected not only for their appeal to the consumer but also for their profitability. Large quantities are produced, transported, stored and marketed and the question of how all these steps can be achieved with the minimal loss of product often dictates which varieties are available at a price acceptable to the consumer. As an example, there were once not so long ago thousands of apple varieties, but now only a few are available in the supermarket.
Cross-breeding programs aiming at the incorporation of genetic traits to face the problems due to the reduction of genetic diversity often involve cross-breeding with wild varieties,and this has the potential to increase the available gene pool. There are, however, important caveat to note here. The first is the ready availability of the wild variety which may not always be the case. The second is that production of 60% of all seeds for agricultural crops worldwide is now in the hands of just a few large companies, and this has led to problems due to lack of competitiveness, monopolistic practices and a growing number of patents.
The number of patents on plants worldwide has gone up from just under 120 in 1990 to 12,000 and counting, and they give the patent owner mostly exclusive rights to breed, grow and sell a plant variety while restricting farmers from sowing, planting, harvesting or breeding it without permission. Seed companies, which are predominantly based in the global north, claim that upholding patent laws is necessary because it also guarantees the financing of new inventions but critics argue that patents block access to genetic material for farmers and minimize biodiversity, the diversity of species and increase farmers’ dependency on seed producers. This has led to the introduction by many countries, notably in the Southern Hemisphere and South-East Asia of legislation restricting patent rights.
In 2018, the General Assembly of the UN adopted the Declaration on the Rights of Peasants and Other People Working in Rural Areas which among others include “the right to save, use, exchange and sell their farm-saved seed or propagating material and the right to maintain, control, protect and develop their own seeds and traditional knowledge”. How this will play out in the future remains to be seen.