(January 2000) Along with the spread of democracy, the advent of television and the Internet, and ventures in space, population change was a distinguishing characteristic of the 20th century. World population rose to 6 billion in 1999, from under 2 billion in 1900. But what besides growth was going on?

To answer that question, PRB asked experts from around the world to create lists of what they felt were the 20th century’s most important population trends and events. Their submissions were fascinating and wide-ranging. We chose highlights from each of their lists to emphasize both the breadth and the magnitude of the changes they cited from the 20th century — now the new “last century.”

Joseph Chamie, director, UN Population Division: “The 20th century was the most remarkable century ever demographically, and it is unlikely to be repeated in the future. It had more demographic firsts than any other century: the highest rate of growth; the highest annual increment; the shortest period in history to add a billion people; unprecedented declines in fertility; unparalleled increases in life expectancy with dramatic declines in mortality; and rapid urbanization and the emergence of megacities.”

Jean-Claude Chesnais, senior research fellow, Institut National d’Etudes Démographiques (Paris): “U.S. supremacy — a high-tech population with sustained growth; the changing ethnic composition in the United States and possible integration of the two Americas; and the changing religious composition of Europe, where Islam is becoming the second religion of a growing number of countries.”

Leon Bouvier, adjunct professor of demography, Tulane University School of Public Health: “The incredible decline in fertility in Europe in such a brief period; the Bangladesh fertility decline; the AIDS epidemic in Africa; and increased immigration to western European countries.”

Mercedes Concepcion, member, Board of Commissioners, Philippine Population Commission; professor emeritus, University of the Philippines: “The increase in the absolute numbers and proportions of older persons. With falling fertility rates and lengthening life expectancies, the populations of Asia and the Pacific are aging rapidly. … The modern household has fewer members to generate mutual physical and emotional support. Consequently, the support of young children and older persons presents more difficulties than in the past.”

Fred Sai, president, Ghana Academy of Arts and Sciences; former president, International Planned Parenthood Federation: “I would rate the development of hormonal contraceptives, particularly the pill, as the most important technological development. I consider article 14(f) of Bucharest [1974 UN World Population Conference], which gave couples and individuals the right to family planning, a fundamental change to make programs much more accessible to those who need them. The gradual evolution of NGOs as partners with a voice at both national and international levels has helped with relevant policy and program evolution. [And] with the founding of the UNFPA in 1969, the UN system showed how important it considered population and related issues.”

Toshio Kuroda, chairman, Japanese Organization for International Cooperation in Family Planning: “The Chinese government decided to implement its ‘one child per couple’ policy in 1979. The Limits to Growth published in 1972 by the Club of Rome drew worldwide attention to the effects of population increase on economic growth and human survival. [And] the First Asian Population Conference was held in New Delhi in 1963. It was the first official conference where population policy including family planning was discussed.”

Francisco Alba, professor, El Colegio de México: “The virtual stagnation of population growth in economically rich, industrialized countries along with increased population in economically poor, technologically laggard, and incipiently industrialized societies; the enfranchisement of women; and the fluid nature of couples in families (greater incidence of divorce and more partners in a lifetime).”

A.R. Nanda, secretary, Indian Department of Family Welfare; former census commissioner: “The educational attainment of the population (literacy) and a minimum standard of education; drinking water facilities and sanitation; decreases in infant and child mortality; antenatal care; and acceptance of family planning.”

Pape Syr Diagne, director, Centre for African Family Studies (Nairobi): “The International Conference on Population and Development [in 1994] and the broadened definition of reproductive health (population issues and numbers are not key but people and their health are); Margaret Sanger and the Planned Parenthood movement; and the transition from large, extended families to smaller, nuclear families in sub-Saharan Africa.”

Nafis Sadik, executive director, UN Population Fund: “Countries have initiated the adoption of population policies; promotion of gender equality and equity, and women’s empowerment; adoption of broad reproductive health/rights policies; prevention and treatment of sexually transmitted diseases including HIV/AIDS; and increased access to education for women and girls.”

Allison Tarmann is editor of Population Today.