In Dominant Animal (Island Press), ecologists Paul and Anne Ehrlich, who authored the highly influential The Population Bombforty years ago, recalibrate their vision and find that, despite some progress (heading off some of their more dire 1968 predictions), our species is still overshooting the capacity of the planet to sustain itself, and must change our ways.

How has the situation changed over the forty years since you wrote The Population Bomb? You predicted then that unless there was a significant drop in the global birthrate, the world would be facing severe crises.

Paul: Biotechnological advances in agriculture, such as the green revolution, have been more successful than we expected, and this has meant that there is more food around. The size of famines over the past 40 years has been less. On the other hand, 40 years ago we didn’t know about the dangerous thinning of the ozone layer and we underestimated the danger of the greenhouse effect. We thought that global warming would only become a serious problem at the end of the 21st Century.

Anne: Since we wrote our book, programs have been put in place to allow women reproductive choice not only in the United States but in the developing sector as well. We predicted that the population would double by 2003, and that didn’t happen, I think in part because of the impact of our book.

The latest predictions are that the population will double in 2012. Do you believe the government should intervene to promote smaller families?

Anne: Not at all. When women gain the ability to choose when to have children, most want to stop at two. In Japan and Europe, governments are offering incentives to people to have children in order to sustain their populations. A norm of two children per family is optimal.

Paul: The success of the Chinese in limiting their birthrate compared to the Indians has resulted in a higher overall standard of living for the Chinese, but this can be achieved without introducing legal sanctions against larger families.

Isn’t there a problem in sustaining the elderly as they become a greater proportion of the population?

Paul: People who talk about the population pyramid being out of balance are making a fundamental error. They forget that children are dependants who must be supported. This has to be balanced against the increase of elderly needing support. By increasing the availability of health care to the population, [the elderly’s] ability to continue making a contribution to society will also increase.

Do you believe that Americans ultimately will have to accept a lower standard of living and shrinking reliance on technology in order to preserve the environment?

Paul: No, not as long as we keep the birth rate down and use technology cleverly. We need to use energy more carefully and cleverly. The problem is how we use our incredible talents to keep from destroying the environment we depend upon. If we do it right we can enhance our quality of life without destroying our children’s future, and leave them an incredibly wonderful world.