Paul Ralph Ehrlich (May 29, 1932 – March 13, 2026) was an American biologist, author, and environmentalist who warned about the effects of population growth, such as food shortages and the loss of natural resources. He held the title of Bing Professor of Population Studies at Stanford University’s Department of Biology. Ehrlich began working at Jasper Ridge Biological Preserve in 1959. He collaborated with other biology professors to help Stanford University establish Jasper Ridge as a protected area for scientific research in 1973.

Ehrlich gained attention for the 1968 book The Population Bomb, which he co-authored with his wife, Anne H. Ehrlich. In the book, they wrote that "in the 1970s, hundreds of millions of people will starve to death despite efforts to address the problem now." This idea has led some historians and critics to label Ehrlich as a neo-Malthusian, a term used to describe those who believe population growth will cause serious problems.

Opinions about Ehrlich’s predictions vary. Statistician Paul A. Murtaugh stated that Ehrlich was mostly correct in his warnings. However, Ehrlich faced criticism for his pessimistic views and for some predictions that did not come true. In 2004, he acknowledged that population growth was slowing but argued that overuse of resources by wealthy nations remained a major issue. He believed his warnings about disease and climate change were accurate. Journalist Dan Gardner pointed out that Ehrlich showed inconsistencies in his predictions, as he credited himself for correct forecasts but did not admit when he was wrong.

Early life, education and academic career

Paul Ehrlich was born in Philadelphia, Pennsylvania, to William Ehrlich and Ruth Rosenberg. His father worked as a shirt salesman, and his mother was a teacher and scholar of Greek and Latin. Ehrlich’s mother’s ancestors came to the United States from Germany in the 1840s, and his father’s grandparents later moved from the Galician and Transylvanian regions of the Austrian Empire. Ehrlich grew up in a Jewish household that did not support Zionism. As a child, his family moved to Maplewood, New Jersey, where he attended Columbia High School and graduated in 1949.

Ehrlich studied entomology, focusing on butterflies. He earned a bachelor’s degree in zoology from the University of Pennsylvania in 1953, an M.A. from the University of Kansas in 1955, and a Ph.D. from the University of Kansas in 1957. His doctoral work was supervised by Charles Duncan Michener, a well-known bee researcher. His dissertation was titled The Morphology, Phylogeny and Higher Classification of the Butterflies (Lepidoptera: Papilionoidea).

During his studies, Ehrlich helped survey insects in regions near the Bering Sea and the Canadian Arctic. Later, with a fellowship from the National Institutes of Health, he studied the genetics and behavior of parasitic mites. In 1959, he began teaching at Stanford University. He became widely recognized for introducing the term coevolution in a 1964 paper he co-authored with botanist Peter H. Raven. In this paper, they explained how insects and their food plants influence each other’s development, leading to the wide variety of both groups.

This paper had a major impact on the field of chemical ecology. In 1966, Ehrlich was promoted to professor of biology, and in 1977, he was appointed to the Bing Professorship. In 1984, he founded the Center for Conservation Biology at Stanford University. Ehrlich was a member of the American Association for the Advancement of Science, the United States National Academy of Sciences, the American Academy of Arts and Sciences, and the American Philosophical Society.

Overpopulation debate

A lecture by Paul Ehrlich on overpopulation was broadcast on radio in April 1967 at the Commonwealth Club of California. The lecture's popularity led to more attention, and David Brower, the leader of the Sierra Club, and Ian Ballantine of Ballantine Books suggested Ehrlich write a book on the topic. Ehrlich and his wife, Anne H. Ehrlich, worked together on the book The Population Bomb. However, the publisher required only one name to be listed as the author, so only Paul Ehrlich's name appeared.

Although Ehrlich was not the first person to warn about population issues—concerns about overpopulation were common in the 1950s and 1960s—his ability to engage with the media helped spread awareness. Ehrlich appeared on The Tonight Show Starring Johnny Carson more than twenty times, with one interview lasting an hour.

The first edition of The Population Bomb began with the statement:

Ehrlich argued that the human population was too large. He believed that while the effects of overpopulation could be lessened, serious problems like famine, disease, and social unrest could not be avoided.

Ehrlich proposed solutions to overpopulation. In The Population Bomb, he wrote, "We must control population at home, using incentives and penalties, and if needed, force if voluntary methods fail. We must use political power to encourage other countries to combine agricultural development with population control." He supported voluntary measures, such as making birth control and abortion easily available.

Years later, Ehrlich remained well-known, but the book's predictions did not come true. The New York Times noted that his "apocalyptic predictions" were not accurate. Science writer Charles C. Mann wrote that the book's ideas "fueled an anti-population-growth movement that led to human rights abuses worldwide," including forced sterilizations. Ehrlich's focus on India, for example, was criticized for emphasizing emotions over data.

Ehrlich and his wife never publicly admitted their predictions were wrong. They claimed their ideas were mostly correct, despite criticism from experts.

In The Population Explosion, the Ehrlichs argued that the population crisis they described in The Population Bomb had occurred, with hunger and famine becoming more severe. Many people agreed that population issues needed attention, such as sociologist Frank Bean, who wrote in The New York Times that "it is not merely prudent but imperative that we confront population issues now." Others, like sociologist Thomas J. Espenshade, criticized the book for being overly alarming. The book was also criticized for suggesting government control over population growth was necessary, which some said limited personal reproductive rights.

Later reviews found errors in the book's claims. For example, the book's claim that global food production had reached a peak was incorrect. Predictions of a severe food shortage in India by the 1990s also did not happen.

In a paper, the Ehrlichs discussed their belief about the "optimal" human population size, based on current technology. They estimated that the ideal population was between 1.5 and 2 billion people. They suggested creating policies to influence birth rates.

During a 2004 interview, Ehrlich acknowledged that some of his predictions from The Population Bomb did not occur. However, he said he felt "little embarrassment" and reaffirmed his belief that overpopulation is a major problem. He noted that 600 million people were very hungry, and billions were undernourished, and he believed his predictions about disease and climate change were correct. He also said the book's prediction of widespread famine by 1985 was "way too optimistic."

In a 2008 discussion, Ehrlich criticized the United States for needing to control its population and consumption to set an example for other countries. He still believed governments should discourage families from having more than two children, such as by taxing larger families.

In 2011, as the world's population reached seven billion, Ehrlich argued that the next two billion people would cause more harm than the previous two billion, as humans would need to use more environmentally damaging resources. As of 2013, Ehrlich continued researching population and resource issues, focusing on endangered species, environmental ethics, and biodiversity. He worked with Dr. Gretchen Daily on countryside biogeography, which studies how to make human-altered areas friendly to wildlife. His research group at Stanford University studied the Bay checkerspot butterfly.

The population disaster Ehrlich predicted, such as "hundreds of millions" of deaths from starvation in the 1970s and "tens of millions" of deaths in the United States in the 1970s and 1980s, did not occur. Slower population growth and new food production methods increased food supplies faster than population growth. Ehrlich still believed the human population was too large, threatening human survival and the environment. In 2015, he said if he wrote the book today, "My language would be even more apocalyptic." In 2018, he stated the optimal population size was between 1.5 and 2 billion people. In 2022, he contributed to the "Scientists' warning on population," published in Science of the Total Environment, which estimated a sustainable population size to be between 2 and 4 billion people.

Reception

During the 1960s and 1970s, Ehrlich warned about serious problems caused by population growth. Many experts believed that increasing numbers of people could harm the future of human society, but they disagreed about how bad the situation was and how to fix it.

In the years after Ehrlich made these warnings, critics questioned his main ideas about overpopulation and its effects on the environment and society. They also challenged his solutions and the specific predictions he made since the late 1960s.

One common criticism is that Ehrlich’s predictions often did not happen. For example, Ronald Bailey of Reason magazine called him an "irrepressible doomster" who "has never been right in any of his forecasts of imminent catastrophe." On Earth Day in 1970, Ehrlich warned that "in ten years all important animal life in the sea will be extinct" and that "large areas of coastline will have to be evacuated because of the stench of dead fish."

In a 1971 speech, Ehrlich predicted that by the year 2000, the United Kingdom would be "a small group of impoverished islands, inhabited by some 70 million hungry people." He also said, "If I were a gambler, I would take even money that England will not exist in the year 2000." When these predictions did not come true, Ehrlich responded that "you get things wrong when you predict the future. However, if you look closely at England, they’re having all kinds of problems, just like everybody else."

In The Population Bomb, Ehrlich wrote that India could not feed 200 million more people by 1980. In 1967, he suggested cutting off emergency food aid to India as "hopeless." Later, India’s food production increased greatly through the Green Revolution, and its people’s caloric intake rose even as its population doubled.

Canadian journalist Dan Gardner wrote in his 2010 book Future Babble that Ehrlich did not fully admit mistakes he made in predicting events like material shortages, mass starvation, or disasters in specific countries. Instead, Ehrlich claimed credit for predicting the spread of AIDS or global warming, even though these were not the main focus of his earlier work. Gardner said Ehrlich showed signs of cognitive dissonance, or the inability to accept his own errors.

Barry Commoner criticized Ehrlich’s 1970 statement that "when you realize further efforts will be futile, you may as well look after yourself and your friends and enjoy what little time you have left. That point for me is 1972." Gardner also criticized Ehrlich for supporting strategies from the book Famine 1975!, which proposed ending food aid to countries like India and Egypt. If these strategies had been used, these countries might have suffered famines. Instead, both countries increased food production and now feed larger populations without relying on aid.

Some critics, including those on the political left, argue that Ehrlich focused too much on overpopulation as a problem, rather than on how resources are distributed. Barry Commoner said Ehrlich’s solutions were politically unacceptable because they implied coercion and would harm poor people. He believed that technological and social development would naturally reduce population growth and environmental damage. Ehrlich denied any racism in his ideas and said his policies, if properly implemented, would not be repressive.

In a 2018 interview with The Guardian, Ehrlich said The Population Bomb started a global debate on population issues but admitted the book had weaknesses, such as not emphasizing overconsumption and inequality enough. He argued that "too many rich people" are a threat to the future and that reducing wealth inequality is important. He also said that wealthy individuals, who control global systems, are unlikely to allow such changes.

In a 2022 paper, Ehrlich and his colleague Rodolfo Dirzo argued that reducing fertility rates among wealthy and middle-class people and reducing wasteful consumption could help reduce the human impact on the environment. Their goal was to lower the scale of human activity to address the extinction crisis.

Economist Julian Simon argued in 1980 that overpopulation was not a problem because humans would adapt to changing conditions. He believed that creativity and technology would improve living standards and that most resources could be replaced. Simon noted that prices for many goods had decreased over time. Ehrlich called Simon’s ideas a "space-age cargo cult" and insisted that population growth was outpacing Earth’s ability to provide food, water, and minerals.

This led to the Simon–Ehrlich wager, a bet about resource prices over ten years. Ehrlich chose ten commodities, mostly metals, and lost because their prices dropped by about 30% in a decade. Simon and Ehrlich could not agree on a second bet.

Ehrlich argued, like Norman Borlaug, that intensive farming methods, such as those used in the Green Revolution, delayed environmental disasters. He said that growing populations and wealth are stressing the environment through factors like biodiversity loss, overfishing, and pollution. He believed that reducing consumption and population growth is essential to protect the environment and maintain living standards, but current growth rates are still too high for a sustainable future.

Other activities

Paul Ehrlich helped start the group called Zero Population Growth, which later changed its name to Population Connection, in 1968. He worked with Richard Bowers and Charles Lee Remington. In 1971, Ehrlich was chosen to serve on the Common Cause National Governing Board. He and his wife, Anne, were members of the advisory board for the Federation for American Immigration Reform until 2003. Ehrlich supported the organization Population Matters, which was previously known as the Optimum Population Trust.

Because he was concerned about pollution and after reviewing a doctoral dissertation by his student, Edward Goth III, Ehrlich wrote in 1977 that studies show fluorides can build up in food chains. Evidence that fluorides might harm the environment is growing.

Ehrlich gave speeches at conferences in Israel about desertification. He said, "True Zionists should have small families."

Personal life

Ehrlich married Anne H. Ehrlich (born Howland) in December 1954. They had one daughter named Lisa Marie. He stated that he had a vasectomy in 1963 after his daughter was born.

Ehrlich died due to complications from cancer on March 13, 2026, at a retirement home in Palo Alto, California, where he lived. He was 93 years old.

Awards and honors

• The John Muir Award of the Sierra Club, 1980
• The Gold Medal Award of the World Wildlife Fund International, 1987
• A MacArthur Prize Fellowship, 1990
• The Crafoord Prize in Biosciences, given by the Royal Swedish Academy of Sciences, 1990
• ECI Prize in Terrestrial Ecology, 1993
• A World Ecology Award from the International Center for Tropical Ecology, University of Missouri, 1993
• The Volvo Environment Prize, 1993
• The United Nations Sasakawa Environment Prize, 1994
• The 1st Annual Heinz Award in the Environment (with Anne Ehrlich), 1995
• The Tyler Prize for Environmental Achievement, 1998
• The Dr. A. H. Heineken Prize for Environmental Sciences, 1998
• The Blue Planet Prize, 1999
• The Eminent Ecologist Award of the Ecological Society of America, 2001
• The Distinguished Scientist Award of the American Institute of Biological Sciences, 2001
• Ramon Margalef Prize in Ecology of the Generalitat of Catalonia, 2009
• Member of the Royal Society of London, 2012
• BBVA Foundation Frontiers of Knowledge Award in Ecology and Conservation Biology, 2013

Works

• Ehrlich, Paul R. (2010). "The MAHB, the Culture Gap, and Some Inconvenient Truths." PLOS Biology, Volume 8, Issue 4, Article e1000330. doi: 10.1371/journal.pbio.1000330. PMC 2850377. PMID 20386722.
• Ceballos, Gerardo; Ehrlich, Paul R.; Barnosky, Anthony D.; García, Andrés; Pringle, Robert M.; Palmer, Todd M. (2015). "Accelerated Modern Human-Induced Species Losses: Entering the Sixth Mass Extinction." Science Advances, Volume 1, Issue 5, Article e1400253. Bibcode: 2015SciA….1E0253C. doi: 10.1126/sciadv.1400253. PMC 4640606. PMID 26601195.
• Ceballos, Gerardo; Ehrlich, Paul R.; Dirzo, Rodolfo (May 23, 2017). "Biological Annihilation Due to the Ongoing Sixth Mass Extinction, as Shown by Vertebrate Population Losses and Declines." PNAS, Volume 114, Issue 30, Pages E6089–E6096. Bibcode: 2017PNAS..114E6089C. doi: 10.1073/pnas.1704949114. PMC 5544311. PMID 28696295.
• Dirzo, Rodolfo; Ceballos, Gerardo; Ehrlich, Paul R. (2022). "Circling the Drain: The Extinction Crisis and the Future of Humanity." Philosophical Transactions of the Royal Society B, Volume 377, Issue 1857, Article 20210378. doi: 10.1098/rstb.2021.0378. PMC 9237743. PMID 35757873.