LINDAU, Germany—A 93-year-old Nobel laureate in physiology or medicine received a standing ovation from hundreds of scientists on June 30 at the end of a speech in which he urged the world's young people to take measures to control runaway population growth in order to resolve related ills that have resulted from humans' remarkable evolutionary success as a species.

Christian de Duve received the Nobel Prize in 1974 for discovering two cellular organelles, lysosomes and peroxisomes. In a speech here at the 61st annual Lindau Nobel Laureate Meeting, he outlined the population growth that has occurred in the past 8 million years, with the well-known dramatic acceleration that has occurred in the past 100 years predicted to bring us to a world population of 9 billion or so in 2050.

"We've come to use all the resources that are available for our use on the planet," the Belgian-born biologist said. "We have become tremendously successful but this success has a price."

He ticked off a list of socio-economic and political troubles that have made big and recurring news in the past few decades: exhaustion of natural resources, loss of biodiversity, deforestation and desertification, climate change, energy crises, overcrowding, wars and pollution.

Rather than blaming humanity for all this, he pointed the finger at natural selection, saying that this principle which drives us to reproduce and advance our genes operates "on the here and now level" and pays no heed to imminent food, energy and resource crises. Our ancestors in the Central African forests and savannahs evolved to embrace intra-group selfishness and inter-group hostility as a matter of survival, he said. Today, however, these tendencies do more harm than good.

Humans are the only species that have the ability to act against natural selection, he said, and that is now what must be undertaken.

De Duve articulated and then discarded several more fleshed-out solutions as outlined in his latest book The Genetics of Original Sin (Yale University Press, 2010), including genetic engineering to make humans better adapted for a limited planet, protecting the environment, and advancing women's position in society, as they tend to be less violent and more oriented toward advancing life.

Education is a possible solution too, he said, especially in the hands of religious institutions. But he thinks the world's religions have failed in this endeavor, focusing more on sustaining their ideologies, hierarchies and doctrines than on sustaining humanity. This comment, not made for the first time by the scientist but one that initially took courage to state publicly for a long-time faculty member at the Catholic University of Leuven in Belgium, drew strong applause from the audience. The applause was notable as attendees at the week-long conference were drawn from a wide variety of nations and cultures, including Argentina, Azerbaijan, China, Ghana, India, Korea, New Zealand, Pakistan, Russia, Singapore and Zambia (although most came from Germany, the U.S., India and China, in that order). A total of 23 laureates also attended the gathering.

Population control is the best and only viable solution, de Duve concluded, adding that all of the world's problems today derive from "too many human beings" on Earth. The planet has become too small for all of us, he contended, and "we have to do something about population control, if possible, by birth control."

He then summed up his answer to the world's problems by reading this passage from his book:

"All is not lost, but the writing is on the wall. If we don't act soon to overcome our genetic tendency to intra-group selfishness and inter-group hostility, the future of humanity and of much of life on Earth will be gravely endangered, possibly leading to total extinction under conditions that can only be visualized as apocalyptic."

De Duve then directly addressed the college and graduate students and early career scientists in the audience, saying he will return to the annual meeting as long as he is physically able.

"My generation, our generation, has made a mess of things," he said. "It's up to you to do better. The future is in your hands. Good luck." With that, nearly every person in the auditorium at the conference's venue, Inselhalle, stood up and applauded enthusiastically.

De Duve was not the only laureate here to speak of his concerns about the big problems facing humanity world-wide. In a June 30 interview with Scientific American, Avram Hershko, who won the Prize in chemistry in 2004 for discovering the mechanisms involved in protein degradation, discussed his wish for greater peace in the world, including between Israel and its neighbors, as he articulated in his speech in Stockholm at the ceremony to award his medal.

The 76-year-old native of Hungary noted the world's economic, agricultural and other crises, but added that "all those are nothing compared to the animosity that exists between different nations, different countries. All that is beyond my control, but I'm trying to join different efforts to promote peace."

Images: Christian de Duve at Lindau; Scientific American editor Steve Mirsky with de Duve and a Kindle copy of de Duve's latest book; images by Robin Lloyd