Paul Ehrlich began his career studying butterfly populations. With Peter Raven he coined the term and concept of coevolution — the reciprocal genetic adaptation of two species with close ecological interactions. But to the public and policymakers, Paul is best known for his work as a prominent activist and commentator on overpopulation.

Paul and his wife Anne wrote a controversial book called The Population Bomb. Published in 1968, it became a bestseller and raised awareness of the Ehrlichs’ predictions of the collapse of civilisation due to uncontrolled population growth and depletion of resources. In the decades since, Paul has been a constant and passionate advocate for sustainable development.

Paul cofounded what is now known as the Millennium Alliance for Humanity and the Biosphere, a global body of collaborators working to influence current and future policies and culture. His work in ecology and environmental campaigning has been widely recognised, with many international honours and awards.