Of the tens of thousands of edible plant species people have used throughout history, only a tiny fraction regularly reaches the plate today. Preserving heirloom and native — that is, locally rooted, regionally adapted — varieties is therefore far more than nostalgia.
How much diversity has actually been lost
In widely cited estimates, the FAO suggests that around three-quarters of agricultural crop diversity has been lost since the start of the 20th century, as farmers worldwide shifted from local, multiple varieties to a small number of genetically uniform, high-yield ones. This figure is debated within the research community, since the underlying data is patchy — but the broader trend towards reduced genetic diversity is considered well documented. Of the crop species used worldwide, the FAO notes that today just three crops — rice, maize and wheat — supply a large share of humanity's plant-based calorie and protein intake. This concentration makes global food systems more vulnerable to pests, disease and climate change.
What "native" or "heirloom" actually means
Native or heirloom varieties have developed, or become established, over generations in a particular region, adapted to its soil, climate and pest pressure — unlike globally marketed hybrid varieties, designed to perform consistently everywhere but often blind to local particulars.
Adaptation: Adapted to local soil and climate (Optimised for uniform conditions) Genetic diversity: High, often variable (Low, genetically uniform) Yield under stress: Often more resilient (More vulnerable to variation) Seed saving: Usually reproduces true to type (Often doesn't reproduce true to type)
FAQ
Are heirloom varieties automatically open-pollinated and seed-true? Mostly, yes — unlike many modern hybrids (F1), whose offspring won't grow true to the parent variety.
Why are native varieties often less productive? Because they weren't bred for maximum yield under optimal conditions, but for resilience under locally variable, often suboptimal ones.
Is a seed bank enough to preserve varietal diversity? No — gene banks store samples, but only active cultivation by farmers allows varieties to keep adapting to new environmental conditions.
Is it true that three crops supply most of our calories? According to the FAO, rice, maize and wheat together supply a very large share of the world's plant-based calorie and protein intake — evidence of how little diversity underpins the global food system.
SOURCES
[1] FAO (1997/2010). Second Report on the State of the World's Plant Genetic Resources for Food and Agriculture. https://www.fao.org/agriculture/crops/thematic-sitemap/theme/seeds-pgr/sow/en/ [2] FAO Newsroom. What is happening to agrobiodiversity? https://www.fao.org/3/y5609e/y5609e02.htm [3] Khoury, C.K. et al. (2022). Crop genetic erosion: understanding and responding to loss of crop diversity. New Phytologist. https://nph.onlinelibrary.wiley.com/ [4] Crop Trust. Svalbard Global Seed Vault. https://www.croptrust.org/work/svalbard-global-seed-vault/
