Climate, not brains, shapes leaders and societies, says Jared Diamond

Jared Diamond, a geographer at UCLA, has spent decades asking a deceptively simple question: what actually makes a leader or a society succeed? His new book, 'Profits, Prophets, Coaches and Kings: (When) Do Leaders Make A Difference,' tackles the question by examining political figures, business executives, sports coaches, and religious leaders across history. The answer he arrives at challenges the way most people think about greatness. It is not, he argues, about superior brains or individual genius. It is about climate, geography, and the accidents of birth.

Consider Adolf Hitler. Most people blame him entirely for World War II and the Holocaust. But Germany was already seething with resentment after the Treaty of Versailles. Anti-Semitism was already woven into German society. If Hitler had died in a 1930 car accident—a near miss that actually happened—would the Holocaust have occurred anyway? Diamond, whose own family members were killed in the Holocaust, believes Hitler did make a genuine difference. He was an exceptionally charismatic speaker, a brilliant deceiver, and a risk-taker willing to gamble everything on a single stroke. Yet even Hitler's agency was constrained by forces larger than himself. The question is not whether he mattered, but how much, and in what way.

To understand why some societies rose to dominance and others did not, Diamond points to the Fertile Crescent of the Eastern Mediterranean. This region possessed an abundance of domesticable animals—sheep, goats, horses, pigs, cattle—and crops like wheat, barley, peas, and beans. The Indian subcontinent had domesticated species too, notably cattle and sesame, but far fewer. This geographic accident gave the Fertile Crescent a two-thousand-year head start in agriculture. More food meant larger populations. Larger populations meant people could specialize: some could smelt metals, others could develop writing, still others could build empires. Empires emerged in the Fertile Crescent millennia before they took root in India. None of this had anything to do with the brains of the people involved. It had everything to do with which plants and animals happened to grow where.

Genghis Khan illustrates the point with striking clarity. He built the largest land empire in world history, stretching from the coast of China to the border of Europe. Other steppe chiefs—Attila the Hun, Arpad the Hungarian, Timur the Turk—also built empires, but none remotely as vast. Genghis was undoubtedly a skilled military commander and shrewd strategist. So were the others. Why did he alone achieve such dominion? Only in the last decade have climatologists found the answer. By analyzing tree rings from the Asian steppes, they discovered that the wettest decade in two thousand years fell precisely during Genghis Khan's birth. The heavy rainfall meant abundant hay to feed the sheep and goats, and crucially, the horses that Mongol soldiers rode into battle. Genghis Khan had the extraordinary luck, without knowing it, of being born at exactly the right moment and place. Had he been born twenty years later or two hundred miles away, in a drier climate, history would have unfolded entirely differently.

Diamond uses what he calls the 'Hamlet test' to determine when a leader truly made an irreplaceable difference. The test asks: were there other plausible candidates who could have done the same thing? With Shakespeare, the answer is no. 'Hamlet' is often considered the greatest play in the English language. In Elizabethan times, there were only about twenty major London theatres with the infrastructure and talent to produce great drama. Ben Jonson and Christopher Marlowe were among the finest writers of the era. Yet none of their plays approach 'Hamlet.' If Shakespeare had died young of smallpox, we would not have a comparable work. The pool of possible replacements was so small that we can confidently say Shakespeare made a unique difference.

The test can occasionally be applied to politics. When Botswana became independent, the country had only twenty-two college graduates. Seretse Khama was one of them. He was also chief of the most powerful tribe in Botswana—the tribe whose land held the diamonds that would later be industrially developed. He was one of only twenty-two people who could plausibly have become founding president, and he occupied a uniquely advantageous position. We can apply the Hamlet test to Khama and conclude he made a real difference. We cannot apply it to Mahatma Gandhi. India had hundreds of millions of people. By the end of World War II, Britain's power was visibly declining. Demography and geopolitics suggest independence was inevitable. Yet the way independence came was stamped indelibly by Gandhi. It could have arrived as it did in Kenya, through violent conflict between colonizer and colonized. Instead, Gandhi devised techniques of non-violent resistance that rippled across the world. He made a difference not in whether India would be free, but in how freedom would be won.

Diamond's framework extends to the question of gender. Everywhere on Earth, men have been politically and economically dominant. This has nothing to do with men's brains, he argues. It stems from biological differences: women bear children and typically carry primary responsibility for raising them. Among our closest relatives, the common chimpanzee, males are dominant. Among bonobos, females are. Among elephants and hyenas, females lead. Biological differences, and how societies choose to use them, explain male dominance across human history. Yet this too is changing. When Diamond graduated from college in 1958, highly educated women in his class were furious at the lack of opportunities. Within years, the situation began improving. His sister Susan became the first woman business reporter for the Los Angeles Times, breaking the assumption that only men understood commerce. Scandinavia has gone further, with multiple women serving as political leaders. Afghanistan has moved backward. The point is that societies are already evolving away from biological determinism, suggesting that what seems inevitable can be reshaped by choice and will.