As the world’s population grew in the second half of the twentieth century, food production strained to keep pace, prompting a greater emphasis on rural development and agricultural sciences. Before 1939 the countries of Asia, Africa, and Latin America had collectively produced more grain than they consumed. After 1945, as their populations soared, they began importing food from countries like the United States. Although crops might fail in poor countries, starvation seemed a thing of the past.

Then, in 1966 and 1967, India was hit with a devastating famine. That close brush with mass starvation created widespread alarm that population growth was outpacing food production. The American scientist Paul Ehrlich envisioned a grim future in his 1968 bestseller The Population Bomb, which warned of a population crisis. Ehrlich was not the first scientist to make such dire predictions, and like Thomas Malthus before him (see “Industry and Population” in Chapter 23), he failed to understand the adaptability of farmers and agricultural technology to keep pace with population growth.

Technological improvements countered such nightmarish visions and offered hope. Plant scientists set out to develop new genetically engineered seeds. The first breakthrough came in Mexico in the 1950s when an American-led team developed new strains of high-yield wheat. These varieties enabled farmers to double their yields, though the plants demanded greater amounts of fertilizer and water for irrigation. Mexican wheat production soared. Thus began the transformation of agriculture in some poor countries — the so-called green revolution.

In the 1960s American-backed scientists in the Philippines developed a new hybrid “miracle rice” that required more fertilizer and water but yielded more and grew much faster than ordinary rice. Asian scientists developed similar hybrid strains of rice to meet local conditions.

As they applied green revolution technologies, many Asian countries experienced rapid increases in grain production. Farmers in India increased production more than 60 percent in fifteen years. China followed with its own highly successful version of the green revolution.

The green revolution offered new hope to industrializing nations, though its benefits often flowed to large landowners and export farms that could afford the necessary investments in irrigation and fertilizer. Experiences in China and other Asian countries showed, however, that even peasant families with tiny farms could gain substantially. Indeed, the green revolution’s greatest successes occurred in Asian countries with broad-based peasant ownership of land. Conversely, the green revolution spread most slowly in regions with low rates of peasant landownership.

As the practice of planting genetically engineered crops to increase production grew in the late twentieth and early twenty-first centuries, many feared that such foods would have still-unknown harmful effects on the human body. The loss of biodiversity was also of growing concern. When one or two genetically engineered seeds replaced all the naturally occurring local seeds in an area, food security was threatened. With a shrinking diversity of plants and animals, farmers find it more difficult to find alternatives if the dominant hybrid seed in use becomes susceptible to a particular disease or pest or if a significant climate change occurs.