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Who's in the Video
Joel E. Cohen is a mathematical biologist and Professor of Populations at Rockefeller and Columbia Universities. His research deals with the demography, ecology, epidemiology and social organization of human and[…]

Scientific estimates of Earth’s maximum capacity range in the thousands of billions, but here’s some troubling numbers we have confirmed: Earth’s 6.8 billion residents produce enough food to feed between 9 and 11 billion, yet 1 billion go hungry. How can we change this?

Question: Is the Earth close to reaching maximum capacity

Joel Cohen: I wrote a book in 1995 called How Many People Can The Earth Support, and I made a real effort to find every scientifically, allegedly scientifically-based estimate of how many people the earth can support and I found 66. After I published the book, naturally I found a few more, but they didn't change the conclusions. In the last half century, the estimates ranged of how many people the earth can support, ranged from less than 1 billion to more than a trillion, which is a thousand billions. They can't all be right. What's going on? They make different assumptions. They make different assumptions about the average level of well being that people will want to have, and the distribution of well being. And about how we will settle our differences, whether we'll settle them by peaceful negotiation, or by violent methods and what kinds of economies will we have? Will we trade or will we not trade? And what kinds of families will we have? Who will take care of young people and who will take care of old people? And what kind of an environment do we want? They make assumptions about whether we want parking lots or parks. Jaguars with a small J or Jaguars with a big J. You know, what do we want? Tin cans with wheels or are we going to walk, are we going to take a bike? So they make very different assumptions and I don't think is a question that's completely specified, it's not a science question. And the numbers that are given are too often political numbers, they're numbers intended to persuade you that we have too many people or we could have a lot more people and we don't have enough people. 

I really don't, having spent four years writing that book, I now think that we should pay much more attention to the quality of life of the people who we have now and the quality of life for the children that we're going to have in the next year and 5 years and 20 years. And so I've shifted my emphasis from trying to answer a question that's not well formulated in the first place, to what can we do to improve life for ourselves and for the children, and especially for the billion people who are chronically hungry now. It's amazing to me—so you ask about how many people can the earth support? Last year, we grew enough grain to feed decently between 9 and 11 billion people, okay? We have under 7 billion, and of those, 1 billion are chronically hungry, they're not getting enough. How is it possible? We're growing 9 to 11, we've got a billion hungry people. We're only 7 billion altogether, how does that work? For every 3 kilograms of grain that goes into a human mouth, we put 2 kilograms of grain into an animal mouth. And we have put animals in the queue for food ahead of a billion people. And the reason is, the billion people are poor. They got no money and they're economically invisible because the price of food doesn't take account of hunger. Especially children. They've got no, they don't have it. And so they are hungry, we've got a billion hungry people and we're feeding 40% of the consumed grain to animals, not to mention the one-sixth that goes into the machines. So I think we've got a problem, when we put machines and animals ahead of people. 

Question: How can we stop wasting so much food

Joel Cohen: Well, I don't know that it's wasted. The people who are getting rich are demanding the meat, they want, in the economic sense, they're buying meat, they want it. And the farmers are supplying where there's demand. What I think we need to do is take several steps to break the cycle of poverty so that the people who are poor can also get grain or meat or whatever they want. I mean, if they've vegetarian, fine, let them eat vegetables. If they want meat, let them buy meat. But part of the problem is that meat consumers in rich countries have no idea of the environmental impacts of eating meat. So the price of meat does not reflect the real costs in terms of well being for the earth. It does not reflect the land degradation due to over-grazing. It does not reflect the water pollution, it does not reflect the greenhouse gas emission that affects everybody whether you eat meat or not. So the prices do not incorporate the real cost. The price of meat doesn't incorporate the health risks. The infectious diseases, the e-coli infections, the salmonella. You know, there was just another food recall in the New York Times yesterday because of salmonella.  It doesn't reflect the losses of species. 

So the first thing I would do is get the prices of meat to reflect all of the costs and I think that would be a signal of what's in, to the consumer, and the other thing is to provide the consumers in the west with information. What are the consequences of eating meat? But that's not enough, because there's a whole billion people who are outside of the price system and for them, I think we need three kinds of interventions. You ask what to do? Here are three things I think we should do. There are about 200 million women in the world who have an un-met need for contraception. That means if you ask them, do you want to have another child and they say no, and are you having intercourse and exposed to the risk of conception and they say yes, they have an un-met need for contraception. There are about 200 million. It would cost about $4 billion to fix that problem. That is not a big deal, we could fix that. 

The second thing, and we should be educating teenage boys and girls about contraception before they become parents. Secondly, we should have nutrition education for pregnant women, for parents, and for teenagers, how to make a whole protein out of whatever your local food is. Rice and beans, it’s a great combination, it gives you a complete protein, but in Liberia, a lot of people eat just the polished white rice because that’s the upper class food, and beans is cheap food and they consider that not dignity. This is where culture comes in, eating poor people’s food is not dignified, as a result, they get malnutrition. But if we could teach people to make whole protein from whatever is locally available, by nutrition education, that would be a big step. 

And the third thing is, as a temporary measure, we need to provide good diets to pregnant women, lactating women and their offspring, and infants up to the age of three, because that's when their brains are being laid down and give them a start to get out of this trap of poverty. The poverty makes them have bad diets and the bad diets stunts their mental and physical growth and that keeps them in poverty. So there are some specific things that we can do to get out of this bind.