The human population has swelled so much that people alive today outnumber all those who have ever lived, says a rumor that has circulated for years. The rumor is an embellishment of one started in the 1970s, which asserted that 75 percent of all people ever born were alive at that time. In 1995 demographer Carl Haub of the Population Reference Bureau, a nongovernmental organization in Washington, D.C., addressed the issue by calculating how many people had ever existed, a number he updated in 2002. To arrive at the 2002 figure, he considered when humans first arose and estimated population growth rates during different historical periods.
Based on an estimate made in the 1973 United Nations report Determinants and Consequences of Population Trends, Haub assumed that the first Homo sapiens appeared around 50,000 years ago and counted the population at that time as two—his Adam and Eve.
Little is known about life that long ago, but by examining data from the U.N. and elsewhere, Haub calculated that by 8000 B.C., the time of the Middle East's agricultural revolution, the earth held some five million people.
Between the rise of farming and the height of Roman rule, population growth was sluggish; at a rate of less than a tenth of a percent per year, humanity's number crawled to about 300 million by A.D. 1. That total then fell as plagues wiped out large swaths of people. (The Black Death in the 14th century wiped out at least 75 million.) As a result, by 1650 the world population had increased only to about 500 million. But by 1850 it doubled to more than one billion thanks to improved agriculture and sanitation. And by 2002 the planet's population had exploded, reaching 6.2 billion.
Together such figures revealed that slightly more than 106 billion people had ever been born. Of that number, those alive in 2002 constituted only about 6 percent. (See www.prb.org/Articles/2002/HowManyPeopleHaveEverLivedonEarth.aspx for more details on Haub's math.) Today more than 6.5 billion people inhabit the planet, according to the U.N. “[It is] almost surely true people alive today are some small fraction of [all] people,” says Joel E. Cohen, a professor of populations at the Rockefeller University and Columbia University. For the myth to be valid now, more than 100 billion would have to be alive.
Myth Today, Truth Tomorrow?
What about the future? Recently the population has been increasing by about 1.2 percent each year, down from the late 1960s peak of about 2 percent. Some industrial countries, such as Japan, have very low birth rates, and their populations are actually dwindling, Haub notes. In developing nations, populations continue to grow, although some countries, such as India, are experiencing a slowdown in their growth rates.
Cohen doubts that a doubling of today's population, to 13 billion, will ever occur, never mind its approaching anywhere near 100 billion. Not even the U.N.'s highest projection foresees that much growth, he says. For 2050, the world body's estimates range from 7.3 billion to 10.7 billion people. The median, and most likely, projection of 8.9 billion relies on a gradual slowing of the growth rate. And the U.N. has anticipated that the world population will stabilize at 10 billion inhabitants sometime after 2200. At this rate, the living will never outnumber the dead.
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