Chapter 21: Plants and People

Agriculture emerged independently in at least eleven distinct geographic centers worldwide, with the Fertile Crescent witnessing early domestication of cereals such as barley and wheat alongside legumes and tree crops including olives and figs. Parallel agricultural developments occurred across Asia with rice and soybeans in China and taro, bananas, and citrus in tropical regions, while Africa saw the domestication of sorghum and millet, and the Americas produced maize, beans, squash, potatoes, and cacao. The domestication process fundamentally altered plant morphology through selective breeding for traits like larger seeds, non-shattering seed dispersal mechanisms, and enhanced flavor, creating crops that became increasingly reliant on human cultivation. Co-domestication of animals including sheep, goats, cattle, and pigs provided complementary agricultural systems that supplied protein, labor, and secondary products. The chapter traces how global exploration and trade were driven by demand for spices such as pepper, cloves, and nutmeg, as well as beverage crops like coffee and tea. Modern human populations now depend on a remarkably narrow agricultural base, with fourteen major crops supplying the vast majority of global calories, and just six staple species providing over eighty percent of human food energy. The chapter addresses critical contemporary challenges including soil degradation, water scarcity, and genetic erosion within crop populations, while examining solutions such as the Green Revolution's development of semi-dwarf, disease-resistant varieties. Preserving genetic diversity through seed banks and maintaining wild crop relatives remains essential for protecting against pathogens and environmental stress, as demonstrated by historical crop failures including the Irish potato famine. Emerging agricultural research focuses on developing perennial grain crops, salt and drought-tolerant varieties, and sustainable biofuel sources, while medicinal plant conservation grows increasingly urgent as tropical biodiversity faces destruction.