ARCHIVAL (ABC NEWS, 8-18-69):HOWARD K. SMITH: Overpopulation, so long predicted, has stolen upon us. Its getting worse, week by week.

NARRATION: In the 1960s, a new kind of fear began to spread across America.

ARCHIVAL (ABC NEWS, 7-18-69):BILL GILL: The U.S. could be busting out at the seams by the end of the century.

ARCHIVAL (ABC NEWS, 1-14-74):HOWARD K. SMITH: If we do not by human means limit our numbers, then numbers are going to be limited by more famines and shortages and consequent social conflicts.

NARRATION: The idea that human population was outstripping the Earths ability to support mankind was a powerful one.

And it was one man, Stanford biologist Paul Ehrlich

PAUL EHRLICH (PROFESSOR OF POPULATION STUDIES, STANFORD UNIVERSITY): Population growth will kill you stone cold dead.

NARRATION:who pushed the dramatic message home.

ARCHIVAL (CBS, 12-27-70):PAUL EHRLICH: If we continue to let population grow and if we continue to exploit the underdeveloped countries, if we continue to pollute the seas with a wide variety of compounds and so on, its very difficult for me to picture things holding together for more than another decade or so.

PAUL EHRLICH (PROFESSOR OF POPULATION STUDIES, STANFORD UNIVERSITY): The basic point is so simple. We have a finite planet with finite resources and in such a system, you cant have infinite population growth.

NARRATION: Ehrlich, who had previously focused his scientific research on butterflies, laid out his hypothesis in a slim volume called, The Population Bomb. It was a call to action for many, including a student Ehrlich advised Stewart Brand.

ARCHIVAL (OVERPOPULATION DEMONSTRATION, SAN FRANCISCO BAY AREA TV ARCHIVE, 10-12-69):STEWART BRAND: Theres too many people. And wed like to see people have fewer children and better ones.

STEWART BRAND (FOUNDER, WHOLE EARTH CATALOG): The whole idea that people make more people, who make more people until theres too many people; and by then, its too late. Thats a very persuasive argument.

NARRATION: Adrienne Germain, a womens health advocate, found herself drawn to Ehrlich as well, due to his support of birth control.

ADRIENNE GERMAIN (FORMER PRESIDENT, INTERNATIONAL WOMENS HEALTH COALITION): The message was that we were already in a crisis, and if we didnt have urgent and immediate action, the world would simply destroy itself.

ARCHIVAL (PRESIDENT RICHARD NIXON GIVING A SPEECH, 1967):PRESIDENT RICHARD NIXON: Look at what the year 2000 will be. Our cities are going to be choked with people, theyre going to be choked with traffic, theyre going to be choked with crime, theyre going to be choked with pollution, and they will be impossible places in which to live.

ADRIENNE GERMAIN: Pauls picture of doom and gloom looked real.

ARCHIVAL (CBS EVENING NEWS, 8-28-70):WALTER CRONKITE: Net world population is increasing by 23 people every ten seconds Its clear that world population growth remains completely out of control.

STEWART BRAND: I bought it totally. Many of my friends bought it totally. I organized an event for 60 people to starve in public.

ARCHIVAL (HUNGER SHOW, SAN FRANCISCO BAY AREA TV ARCHIVE, 10-18-69):STEWART BRAND: Maybe anybody whos thinking of having a third child oughta go hungry a week.

STEWART BRAND: The mode became, dont have kids. Theres enough of them in the world. And if your friends have kids, its fine if they feel uncomfortable about that.

PAUL EHRLICH: We had formed an organization called Zero Population Growth and then Johnny took me on The Tonight Show.

ARCHIVAL (THE TONIGHT SHOW, 4-27-77):JOHNNY CARSON: Would you welcome Dr. Paul Ehrlich.PAUL EHRLICH: You have to get the death rate and birth rate in balance and there is only two ways to do it. One is to bring the birth rate down. The other is to push the death rate up.

PAUL EHRLICH:I did the show maybe 20 times, and we went from six chapters and 600 members to 600 chapters and 60,000 members.

ARCHIVAL (THE TONIGHT SHOW, 4-27-77):PAUL EHRLICH: We are starting in now. This is the first step.

ARCHIVAL (ABC, 9-13-71):The Bagleys belong to a growing number of young marrieds who favor ZPG, zero population growth.

ARCHIVAL (STANFORD UNIVERSITY FOOTAGE, 9-13-71):REPORTER: How many children do you have?WOMAN: Two. I have two children.

NARRATION: Ehrlichs views on how to bring that birth rate down were concrete: compulsion if voluntary methods fail, creating a blacklist of people, companies, and organizations impeding population control in the United States. Responsibility prizes for childless marriages.A tax on children. And a luxury tax on diapers and cribs.

STEWART BRAND: The concerns about population became misanthropic and it was taken with so much seriousness, that Paul Ehrlich could recommend things like putting stuff in public water that would make people not as fertile.

ADRIENNE GERMAIN: Panic is not too strong a word to use for some of the advocates that I referred to as true believers.

ARCHIVAL (NBC, 3-25-73):It appears that large families are on the way out and ZPG may be possible.

NARRATION: The idea also took hold in the developing world, where governments like Indias had already begun to embrace population control.

GITA SEN (DEVELOPMENT ECONOMIST, PUBLIC HEALTH FOUNDATION OF INDIA): The core message of the book, population growth outstripping the food supply, resonated quite a bit with Indias elites, with the middle classes. They much preferred to believe that the poor were poor because of too many children rather than being poor because of an unfair, and unequal economic system.

ADRIENNE GERMAIN: If you start with that problem definition, then its almost inevitable that there will be circumstances where governments and other actors will act in a way that is coercive.

NARRATION: In the mid-1970s the Indian government began a controversial program to encourage mass sterilization.

ARCHIVAL (ASSOCIATED PRESS, 10-07-76):INDIRA GANDHI (PRIME MINISTER OF INDIA, 1966-1977, 1980-1984): We do want to create an atmosphere in which people realize the importance of this program.

NARRATION: It led to abuses. Access to food aid and housing were sometimes used as coercion. Others werent even given a choice.

ARCHIVAL (NBC, 12-6-77):REYNOLDS: More than 8 million sterilizations were performed, many forcibly. The people, in the words of one family planning expert, were treated like cattle.

STEWART BRAND: Zero population growth was a tragic frame in the sense that it was assumed that there was no way out, that people would just go on reproducing until there really was a desperate circumstance in the world.

NARRATION: Ehrlichs message could be summed up in a dramatic prediction.

ARCHIVAL (CBS, 1-1-79):PAUL EHRLICH: Sometime in the next 15 years, the end will come. And by the end, I mean an utter breakdown of the capacity of the planet to support humanity.

PAUL EHRLICH: Predictions do not necessarily come true. The critics go in and look at these little stories that wont come true, and when they didnt come true say, Ehrlich was wrong.

NARRATION: But Ehrlich says it could still be just a matter of time.

PAUL EHRLICH: One of the things that people dont understand is that timing to an ecologist, is very, very different from timing to an average person.

STEWART BRAND: How many years do you have to not have the world end to decide that whatever reason you thought the world was gonna end, it actually maybe didnt end because that reason was wrong?

GITA SEN: Ehrlich predicted that by the 1970s India would be starving. Quite to the contrary, the green revolution came to India with a big bang, and a boom, in such a rapid way that India has never looked back.

NARRATION: Although an estimated 3 million children around the world still die of malnutrition every year, the green revolutions farming technology helped lessen rates of hunger in the developing world over the decades, even as the worlds population skyrocketed.

GITA SEN: Theres a tendency to apply to human beings the same sort of models that may apply for the insect world. The difference, of course, is that human beings are conscious beings, and we do all kinds of things to change our destiny.

NARRATION: That story is playing out today in parts of India. In growing cities like Chennai, in the south, large families, once needed for farming, are no longer always seen as the key to success.

VISWANATHAN MURTHY (RESIDENT OF CHENNAI): Previously, my father used to have four children. And my grandfather used to have 7 children. But the things have changed. Even myself I only have 2 children. Even my sister is having only 1 kid because now education becomes first priority here.

STEWART BRAND: The population bomb was defused by urbanization, by people getting out of poverty all over the world, by having enough to eat so you didnt have multiple children in the hopes that some of them would survive. Its somewhat ironic that what Paul Ehrlich saw as a horrible, hellish vision of the future is what turned the population bomb upside down.

NARRATION: Brand says that Ehrlich did succeed in raising awareness about important issues, such as the destructive effect population growth can have on the environment, even if some his predictions didnt come to pass.

PAUL EHRLICH: If you ask me the question, Are there things that I have written in the past that I wouldnt write today? the answer is certainly yes. Ive expressed more certainty because I was trying to bring people to get something done.

NARRATION But his core message remains the same today there are nearly four billion more people in the world and they are consuming more resources than ever before.

PAUL EHRLICH:I do not think my language was too apocalyptic in The Population Bomb.”My language would be even more apocalyptic today.The idea that every woman should have as many babies as she wants is, to me, exactly the same kind of idea as everybody oughta be permitted to throw as much of their garbage into their neighbors backyard as they want.

NARRATION: But, if the world were to succeed in its decades old task to curb population growthwhat then?

STEWART BRAND: What if a large population is not bad, but is good?

ADRIENNE GERMAIN: What many more countries are already trying to come to terms with is aging of the population.

ARCHIVAL (CNN, 9-15-14):WILL RIPLEY: Japan needs more women to have children.

ARCHIVAL (FOX, 2-6-13):LOU DOBBS: America is in the midst of a baby bust.

ARCHIVAL (CBS, 5-30-14):ANCHOR: China is hoping for a new baby boom.

STEWART BRAND: The point at which population peaks around 9 billion in the 2040s or 50s, the story will not be, Oh, my God. We got 9 billion people. How horrible! Itll be, Oh, my God! Were running out of people.