The two naturalists helped to pioneer the field of conservation biology and remained determinedly hopeful that humanity would make better choices.

Over the weekend, two of the country’s leading naturalists, E. O. Wilson and Tom Lovejoy, died a day apart. Wilson, who was perhaps best known for his work on ants, was a pioneer in the field of conservation biology; Lovejoy was one of the founders of the field. The two men were friends—part of an informal network that Wilson jokingly referred to as the “rain-forest mafia”—and there was something eerie about their nearly synchronous passing. “I’m trying very hard not to imagine a greater planetary message in the loss of these biodiversity pioneers right now,” Joel Clement, a senior fellow at the Harvard Kennedy School’s Belfer Center for Science and International Affairs, tweeted on Monday.

The two scientists first met in the mid-nineteen-seventies. At that point, Wilson was in his mid-forties, and teaching biology at Harvard. Lovejoy, a dozen years younger, was working for the World Wildlife Fund. Over lunch, they got to talking about where the W.W.F. should focus its efforts. They agreed that it should be in the tropics, because the tropics are where most species actually live. There wasn’t a good term for what they were trying to preserve, so they tossed one around—“biological diversity”—and put it into circulation. “People just started using it,” Lovejoy recalled, in an interview in 2015. (Later, the phrase would be shortened to “biodiversity.”)

In the seventies, Wilson and Lovejoy were both already deeply concerned about what was happening to the tropics. Increasingly, rain forests were being felled to make room for roads, farms, and logging operations. A decade earlier, Wilson, together with a Princeton professor named Robert H. MacArthur, had published a slim volume called “The Theory of Island Biogeography.” Though the book concerned actual islands, surrounded by water, its implications seemed to extend to isolated habitats, surrounded by human development. According to Wilson and MacArthur’s theory, the smaller these “islands,” the fewer species they would retain…

Read the entire tribute here.