Paul R. Ehrlich obituary: pioneering ecologist who caused controversy by predicting a ‘population bomb’

## Summary
Ehrlich’s book The Population Bomb (1968), written with his wife Anne, made him one of the most influential, if controversial, scientists of the twentieth century. But his overemphasis on population growth at the expense of other factors also influenced oppressive policies in some of the world’s most populous countries, and has not proved to be justified. Global population is crashing, soaring and moving A population plunge could help to mitigate the global biodiversity crisis Subjects History Scientific community Society Evolution Latest on: History Scientific community Society When artificial lightning strikes News & Views 17 MAR 26 Could flies sniff out contraband chemicals? News & Views 10 MAR 26 From the first telephone to videoconferencing in 100 years News & Views 03 MAR 26 The mid-career reset: how to be strategic about your research direction Career Column 20 MAR 26 I paused my PhD for 11 years to help save Madagascar’s seas Career Q&A 20 MAR 26 ‘Unaffordable’ visa price hike threatens Australia’s researcher pipeline Career News 20 MAR 26 I paused my PhD for 11 years to help save Madagascar’s seas Career Q&A 20 MAR 26 AI set to map risks of future climate disasters World View 18 MAR 26 Rethinking AI’s role in survey research: from threat to collaboration Correspondence 17 MAR 26 Jobs Global Talent Recruitment Announcement of the College of Engineering, HZAU Join HZAU's global faculty team to advance research with competitive benefits.

## Article Content
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Paul R. Ehrlich’s book
The Population Bomb
(1968), written with his wife Anne, made him one of the most influential, if controversial, scientists of the twentieth century. In it, he alerted the public to the possible problems of global overpopulation, including the depletion of natural resources and the deterioration of the environmental systems that support humanity. But his overemphasis on population growth at the expense of other factors also influenced oppressive policies in some of the world’s most populous countries, and has not proved to be justified. Ehrlich has died, aged 93.
Ehrlich was born in Philadelphia, Pennsylvania, and attended Columbia High School, a highly rated state school in Maplewood, New Jersey. Butterflies were the childhood passion that drove him into science. Sure of this interest, at 15 years old, he joined the US-based Lepidopterists’ Society.
The scale of the biodiversity crisis laid bare
After earning a zoology degree at the University of Pennsylvania in Philadelphia and then a master’s and PhD in entomology at the University of Kansas in Lawrence, in 1959, Ehrlich secured a post at Stanford University in California. He became a full professor in 1966, after he published his most important work — a 1964 paper with botanist Peter Raven on plant and butterfly co-evolution, a concept they pioneered (
P. R. Ehrlich and P. H. Raven
Evolution
18
, 586–608; 1964
).
The pair suggested that it was because of butterflies that many until-then unexplained chemicals in plants were “immediately explicable”. For instance, when milkweed butterflies extended their range after evolving such that they could feed on dogbanes (
Apocynum
spp.) and milkweeds (
Asclepias
spp.), scientists hypothesized that the plants’ bitter glycoside and alkaloid compounds were helping the animals to avoid predation. Unsurprisingly, research since then has found that there are more-important factors in butterfly–plant interaction patterns, but work in this field is often influenced by this seminal paper.
Ehrlich and Anne wrote
The Population Bomb
in the months after they visited Delhi in 1966. Its publication in May 1968 brought Paul into the public eye. Critics labelled him a ‘population nut’ and accused him of hating children and being ignorant of human creativity. Undeterred by death threats, the couple published
The Race Bomb
in 1977, and included arguments against racial theories of intelligence. The same year, Stanford appointed him Bing Professor of Population Studies, and he remained at Stanford for the rest of his career.
People are having fewer babies: is it really the end of the world?
The Ehrlichs’ work on population had a profound impact on society. It encouraged mass sterilization programmes in India and the one-child policy in China, and influenced how children everywhere were viewed and valued. Ehrlich did not express regret over any of this, even much later in his life.
More positively,
The Population Bomb
helped to encourage the availability of contraception worldwide and the right of women to control their fertility, including through abortion, leading to improved health and well-being.
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doi: https://doi.org/10.1038/d41586-026-00939-5
Competing Interests
The author declares no competing interests.
Related Articles
The scale of the biodiversity crisis laid bare
People are having fewer babies: is it really the end of the world?
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A population plunge could help to mitigate the global biodiversity crisis
Subjects
History
Scientific community
Society
Evolution
Latest on:
History
Scientific community
Society
When artificial lightning strikes
News & Views
17 MAR 26
Could flies sniff out contraband chemicals?
News & Views
10 MAR 26
From the first telephone to videoconferencing in 100 years
News & Views
03 MAR 26
The mid-career reset: how to be strategic about your research direction
Career Column
20 MAR 26
I paused my PhD for 11 years to help save Madagascar’s seas
Career Q&A
20 MAR 26
‘Unaffordable’ visa price hike threatens Australia’s researcher pipeline
Career News
20 MAR 26
I paused my PhD for 11 years to help save Madagascar’s seas
Career Q&A
20 MAR 26
AI set to map risks of future climate disasters
World View
18 MAR 26
Rethinking AI’s role in survey research: from threat to collaboration
Correspondence
17 MAR 26
Jobs
Global Talent Recruitment Announcement of the College of Engineering, HZAU
Join HZAU's global faculty team to advance research with competitive benefits.
Wuhan, Hubei (CN)
Huazhong Agricultural University (HZAU)
Multiple Positions Open in The Stomat

---

## Expert Analysis

### Merits
- He became a full professor in 1966, after he published his most important work — a 1964 paper with botanist Peter Raven on plant and butterfly co-evolution, a concept they pioneered ( P.
- Unsurprisingly, research since then has found that there are more-important factors in butterfly–plant interaction patterns, but work in this field is often influenced by this seminal paper.

### Areas for Consideration
- News & Views 10 MAR 26 From the first telephone to videoconferencing in 100 years News & Views 03 MAR 26 The mid-career reset: how to be strategic about your research direction Career Column 20 MAR 26 I paused my PhD for 11 years to help save Madagascar’s seas Career Q&A 20 MAR 26 ‘Unaffordable’ visa price hike threatens Australia’s researcher pipeline Career News 20 MAR 26 I paused my PhD for 11 years to help save Madagascar’s seas Career Q&A 20 MAR 26 AI set to map risks of future climate disasters World View 18 MAR 26 Rethinking AI’s role in survey research: from threat to collaboration Correspondence 17 MAR 26 Jobs Global Talent Recruitment Announcement of the College of Engineering, HZAU Join HZAU's global faculty team to advance research with competitive benefits.

### Implications
- For instance, when milkweed butterflies extended their range after evolving such that they could feed on dogbanes ( Apocynum spp.) and milkweeds ( Asclepias spp.), scientists hypothesized that the plants’ bitter glycoside and alkaloid compounds were helping the animals to avoid predation.
- Its publication in May 1968 brought Paul into the public eye.
- The Ehrlichs’ work on population had a profound impact on society.
- It encouraged mass sterilization programmes in India and the one-child policy in China, and influenced how children everywhere were viewed and valued.

### Expert Commentary
This article covers population, mar, career topics. Notable strengths include discussion of population. Areas of concern are also raised. Readability: Flesch-Kincaid grade 0.0. Word count: 905.