Thomas was a conservation biologist who began working in the Brazilian Amazon in 1965 and made the fate of tropical forests a public issue.

He was Chief Biodiversity Adviser to the President of the World Bank and Senior Adviser to the President of the United Nations Foundation before becoming Biodiversity Chair of the Heinz Center for Science, Economics and the Environment.

In April 2022, National Geographic Society awarded its most prestigious honor, the Hubbard Medal, to the late Dr. Lovejoy.  Each year, NGS honors individuals for distinction in exploration, scientific research, and discovery with this distinguished accolade.

He introduced the term “biological diversity” to the scientific community in 1980. He received his B.S. and Ph.D. in biology from Yale University and served as University Professor of Environmental Science and Public Policy at George Mason University.