Abstract
The narrowing of diversity in crop species contributing to the world’s food supplies has been considered a potential threat to food security. However, changes in this diversity have not been quantified globally. We assess trends over the past 50 y in the richness, abundance, and composition of crop species in national food supplies worldwide. Over this period, national per capita food supplies expanded in total quantities of food calories, protein, fat, and weight, with increased proportions of those quantities sourcing from energy-dense foods. At the same time the number of measured crop commodities contributing to national food supplies increased, the relative contribution of these commodities within these supplies became more even, and the dominance of the most significant commodities decreased. As a consequence, national food supplies worldwide became more similar in composition, correlated particularly with an increased supply of a number of globally important cereal and oil crops, and a decline of other cereal, oil, and starchy root species. The increase in homogeneity worldwide portends the establishment of a global standard food supply, which is relatively species-rich in regard to measured crops at the national level, but species-poor globally. These changes in food supplies heighten interdependence among countries in regard to availability and access to these food sources and the genetic resources supporting their production, and give further urgency to nutrition development priorities aimed at bolstering food security.
Generated Summary
This research article, published in PNAS, investigates the changes in the diversity of crop species contributing to global food supplies and their implications for food security. The study assesses trends over the past 50 years (1961-2009) in the richness, abundance, and composition of crop species in national food supplies worldwide. Using data from the Food and Agriculture Organization (FAO) of the United Nations, the authors analyzed trends in the richness, abundance, and composition of measured crop commodities in the food supplies of 152 countries, representing 98% of the world’s population. The methodology involves analyzing national per capita food supply data to understand changes in the diversity of crop species. The study examines the spread, abundance, and composition of 52 measured crop commodities, including both individual crops and groups producing similar products. The research also explores the implications of these changes, particularly the increasing homogeneity in global food supplies and its potential impact on food security, by examining changes in the relative importance of different crop plants in national food supplies worldwide over the past 50 years.
Key Findings & Statistics
- National per capita food supplies from both plant and animal sources consistently increased over the past 50 y for all variables.
- Animal foods are becoming increasingly important in contribution to protein and oil crops dominating fat food supplies (Fig. S1).
- From 1961 to 2009, all 52 measured crop commodities, which included both individual crops and groups of crops producing similar products, with the exception of cottonseed oil, increased in geographic spread.
- Wheat, rice, maize, and other ubiquitous crop commodities were among those with the greatest gains in both relative and absolute abundance in national per capita food supplies over the past 50 y (Fig. 1B and Figs. S3 and S4).
- The richness of national per capita food supplies in regard to the 52 measured crop commodities increased consistently over the past 50 y for all variables (Fig. 2 A and B and Fig. S5).
- National food supplies also increased slightly in evenness.
- Dominance (estimated as the proportion of a country’s per capita food supply comprised of the most abundant crop commodity) declined as a global trend over the study period (Fig. 2 E and F and Fig. S7).
- Between 1961 and 2009, homogeneity increased by 16.7%, as measured by the mean change in similarity between each country and the global standard composition, with a maximum (single-country) change of 59.7%.
- Likewise, mean among-country similarity increased by 35.7%.
- East and Southeast Asian as well as sub-Saharan African countries as regional groups displayed the greatest changes in composition toward the global standard over 1961–2009, in association with the greatest increases in measured crop commodity richness and decreases in dominance.
- 50 of the measured crop commodities currently contribute to the top 90% of calories, protein, fat, and weight around the world.
- These crop commodities are composed of 94 crop species from 70 genera from 37 plant families (Table S1).
Other Important Findings
- The study found that national food supplies worldwide became more similar in composition, correlated particularly with an increased supply of a number of globally important cereal and oil crops and a decline of other cereal, oil, and starchy root species.
- The growth in reliance worldwide on these crops heightens interdependence among countries in their food supplies, plant genetic resources, and nutritional priorities.
- The increase in homogeneity worldwide portends the establishment of a global standard food supply.
- The study also notes that the increased food energy, protein, fat, and weight from plants in food supplies worldwide over the past 50 y appear to primarily have been sourced from globally dominant crops specifically reported by FAO.
- The total diversity of crops contributing significantly worldwide has narrowed.
Limitations Noted in the Document
- The study acknowledges that food supply data are not directly equivalent to consumption, as food losses at the household level are not measured.
- FAO food supply data does not specifically report statistics in regard to micronutrients, where species richness may be particularly significant.
- The analyses lack the resolution necessary for elucidating trends in those geographically restricted cereals, legumes, fruits, vegetables, and other crops that may be especially sensitive to changes in the global food system.
- The limited number of individual crop commodities reported by FAO combined with the aggregation of numerous crops into several general commodities is a constraint.
Conclusion
The study concludes that the narrowing of diversity in crop species contributing to the world’s food supplies is a potential threat to food security. The increasing homogeneity in global food supplies, driven by the reliance on a limited number of globally important crops, heightens interdependence among countries. The authors emphasize the need for a broader approach to food security that incorporates nutritional diversity and addresses the potential impact of dietary changes on health. The study highlights that while the number of measured crops available to consumers has increased over time, the overall diversity of crops contributing significantly to the global food supply has narrowed. The research underscores the importance of diversifying diets and promoting sustainable agricultural practices to ensure food security and address the challenges posed by climate change and environmental degradation. The authors suggest, “the growth in reliance worldwide on these crops heightens interdependence among countries in their food supplies, plant genetic resources, and nutritional priorities.” They also note that, “The increasing reliance on a suite of truly global crop commodities implies a narrowing in the diversity present in global agricultural systems as a whole, necessitating an equivalent expansion in attention to production stability for these crops.”