Then God said, “I give you every seed-bearing plant on the face of the whole earth and every tree that has fruit with seed in it. They will be yours for food.” (Gen. 1:29)
In Ruth Krauss’s classic book The Carrot Seed, a silent little boy disregards all naysayers, patiently watering and weeding around his plant until at last a great carrot sprouts up, “just as the little boy had known it would.”
Though famous for how its simple drawings transformed the genre of pictures books, Krauss’s story also tells us something profound about our relationship with nature. Even children know that the tiniest pip contains what George Bernard Shaw called “fierce energy”—the spark and all the instructions needed to build a carrot, an oak tree, wheat, mustard, sequoias, or any one of the estimated 352,000 other kinds of plants that use seeds to reproduce. The faith we place in that ability gives seeds a unique position in the history of the human endeavor. Without the act and anticipation of planting and harvest, there could be no agriculture as we know it, and our species would still be wandering in small bands of hunters, gatherers, and herdsmen. Indeed, some experts believe that Homo sapiens might never have evolved at all in a world that lacked seeds. More than perhaps any other natural objects, these small botanical marvels paved the way for modern civilization, their fascinating evolution and natural history shaping and reshaping our own.
We live in a world of seeds. From our morning coffee and bagel to the cotton in our clothes and the cup of cocoa we might drink before bed, seeds surround us all day long. They give us food and fuels, intoxicants and poisons, oils, dyes, fibers, and spices. Without seeds there would be no bread, no rice, no beans, corn, or nuts. They are quite literally the staff of life, the basis of diets, economies, and lifestyles around the globe. They anchor life in the wild, too: seed plants now make up more than 90 percent of our flora. They are so commonplace, it’s hard to imagine that for over 100 million years other types of plant life dominated the earth.
Roll back the clock and we find seeds evolving as trivial players in a flora ruled by spores, where tree-like club mosses, horsetails, and ferns formed vast forests that remain with us in the form of coal. From this humble beginning, the seed plants steadily gained advantage—first with conifers, cycads, and ginkgoes, and then in a great diversification of flowering species—until now it is the spore bearers and algae that watch from the sidelines.
This dramatic triumph of seeds poses an obvious question: Why are they so successful? What traits and habits have allowed seeds, and the plants that bear them, to so thoroughly transform our planet? The answers reveal not only why seeds thrive in nature, but why they are so vital to people.
Seeds Nourish. Seeds come pre-equipped with a baby plant’s first meal, everything needed to send forth incipient root, shoot, and leaf. Anyone who has ever put sprouts on a sandwich takes this fact for granted, but it was a critical step in the history of plants. Concentrating that energy into a compact, portable package opened up a huge range of evolutionary possibilities and helped seed plants spread across the planet. For people, unlocking the energy contained in seeds paved the way for modern civilization. To this day, the foundation of the human diet lies in co-opting seed food, stealing the nourishment designed for baby plants.
Seeds Unite. Before seeds, plant sex was pretty dull stuff. When they did it at all, plants made sure the act was quick, out of sight, and usually with themselves. Cloning and other asexual means were common, and whatever sex happened rarely mixed genes in a predictable or thorough way. With the advent of seeds, plants suddenly began breeding in the open air, dispersing pollen to egg in increasingly creative ways. It was a profound innovation: unite the genes from two parents on the mother plant and package them into portable, ready-to-sprout offspring. Where spore plants interbred only occasionally, seed plants mixed and remixed their genes constantly. The evolutionary potential was enormous, and it’s no coincidence that Gregor Mendel [Augustinian monk and “father of modern genetics”] solved the mystery of inheritance by a close examination of pea seeds. Science might still be waiting to understand genetics if that famed pea experiment had instead been “Mendel’s Spores.”
Seeds Endure. As any gardener knows, seeds stored through the winter months can be planted the following spring. In fact, many seeds require a cold spell, a fire, or even passage through an animal gut to trigger their germination. Some species persist in the soil for decades, sprouting only when the right combination of light, water, and nutrients makes conditions right for plant growth. This habit of dormancy sets seed plants apart from nearly all other life forms, allowing great specialization and diversification. For people, mastering the storage and manipulation of dormant seeds paved the way for agriculture and continues to determine the fate of nations.
Seeds Defend. Almost any organism will fight to protect its young, but plants equip their seeds with an astonishing and sometimes deadly assortment of defenses. From impenetrable husks and jagged spikes to the compounds that give us hot peppers, nutmeg, and allspice, not to mention poisons like arsenic and strychnine, seed defenses include some surprising (and surprisingly useful) adaptations. Exploring the topic illuminates a major evolutionary force in nature and shows how people have co-opted seed defense for their own ends, from the heat in Tabasco sauce to pharmaceuticals to the most beloved seed producers of all, coffee and chocolate.
Seeds Travel. Whether tossed up by storm waves, spun on the wind, or packaged in the flesh of a fruit, seeds have found countless ways to get around. Their adaptations for travel have given them access to habitats spanning the globe, spurred diversity, and led people to some of the most essential and valuable products in history, from cotton and kapok to Velcro and apple pie.
Thor Hanson is a Guggenheim Fellow, a Switzer Environmental Fellow, and an award-winning author and biologist. His most recent book is The Triumph of Seeds: How Grains, Nuts, Kernels, Pulses, and Pips Conquered Nature and Shaped Human History. Copyright @ 2015 by Thor Hanson. Published by Basic Books. Used with permission of Curtis Brown, Ltd. Scripture epigraph added by the editors.
