The Self-Taught Gardener: Strength in diversity

There is every reason in the world to celebrate and maintain the diversity of all species, beginning with our own.

This weekend as the world turned its attention to Charlottesville, I was also engrossed in a story about our struggle as a culture to maintain diversity. My experience came from a book long on my must-read list: Shattering by Pat Mooney and Cary Fowler. The book, published 27 years ago, describes the loss of genetic diversity amongst our food crops. Like many great writings, it is completely relevant today. And as the news came over the airwaves of the happenings in Charlottesville, it reminded me that diversity is often a controversial topic for humankind.

The early sections of Shattering examine how we slowly evolved from societies of hunters and gatherers and became nations of farmers, how we went from eating a broad range of available sources of proteins and carbohydrates, often foraging small amounts of a broad range of species to meet our nutritional needs, and how we slowly stepped back from that process, setting down roots, cultivating the earth, and growing plants that would provide for our needs. Obviously, in previous millennia there was neither understanding of genetics nor desire to maintain the “purity of a strain.” On the contrary, in early agrarian cultures, the selections that evolved as humankind saved seeds or simply allowed plants to reseed themselves were often genetically broad in their scope. These selections, often known as landraces, are collections of a species that have been grown in the same region over a period of time and have slowly adapted to the area in which they are cultivated.

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Landraces, such as this sorghum, may prove essential to our well-being because of the genetic diversity they hold.

Contrary to the hybrids and GMOs commonly sown today on many American farms, these landraces were diverse in their genetic makeup, and that genetic breadth was critical to their success. Some of the seeds contained alleles that made them stronger in fighting off disease or surviving drought or cold temperatures, allowing some of the crop to forge ahead, regardless of the conditions of that particular season. Many of the seeds of the same species even had different germination requirements. If growing conditions changed and some of the plants that had germinated did not make it, there was within that same species another range of seed with different levels of inhibition to germination that could still come up and provide its bounty that season. The variation helped ensure a food supply for these newly formed communities of farmers who had left behind a hunting and gathering existence.

PHOTO 3 -wheat landraces
Landraces, such as this grain crop, are loosely related members of a species that have been allowed to evolve over time and are often associated with being isolated to a particular area. Unlike most cultivated varieties, they have a greater genetic breadth, helping to ensure their long-term health and survival.

Diversity also meant variability in terms of when grains might mature, the size of the kernels, and how they were held on the plant. With this diversity, harvesting took place over a longer period of time. Compare this to the way today’s growers of grains harvest, using combines that require all crops to mature at the same time. It would appear that consistent maturation would be a great advantage. Yet, as I interpret what Mooney and Fowler are saying, harvesting crops did not represent an overwhelming labor drain for early agricultural societies; rather it was simply the work that they did to ensure an adequate food supply in the face of unpredictable seasonal conditions. Genetic diversity was an insurance policy for their survival from year to year.

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A wide gene pool produces an interesting variety of corn, and assures survival of the species

As the world moved forward and agriculture became more scientific in its approach to cultivation, farmers slowly selected out this variability, creating plants that were narrow in their gene pool but more predictable in how they would perform. This may have been good for agribusiness, but it represented a tremendous loss to our food supply. By sacrificing the adaptability of these landraces, we lost the great advantage that these adaptable landraces brought to our tables — not just greater variety but also the strength that comes from knowing that our food crops can sustain us through hard times because of their genetic breadth and ability to adapt.

And as I was engrossed in this age-old lesson, the news that broke in Charlottesville on Saturday made me realize that while modern life and the science that have come with it have had their share of advantages, there is every reason in the world to celebrate and maintain the diversity of all species, beginning with our own.

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