In January 2017, I played telephone tag with E.O. Wilson.

Routinely compared to Darwin (‘a modern-day Darwin’ or ‘Darwin’s natural-heir’ among others) E.O. Wilson is renowned for his work on evolution, biogeography, sociobiology and myrmecology—the study of ants. I’ve interviewed thousands of scientists—and am not usually prone to being starstruck. But I made an exception for E.O. Wilson: listening to his southern drawl in my voicemail left me a little bit giddy.

Wilson and I finally got the chance to chat later that month, but it wasn’t about his storied career in evolutionary science—not about island biogeography or sociobiology—or his favorite topic, ants. Instead, we talked about his latest book Half-Earth where he passionately proposed setting aside half the planet for non-human species. Although 87 at the time of our interview, Wilson sounded more like an advocate at the height of his powers.

How do we stave off mass extinction, ecological collapse, and create a panacea for climate change? Wilson believed he had the answer: half-earth.

On December 26^th, E.O. Wilson died in Burlington, Massachusetts at the age of 92.

For a man who devoted most of his life to hard evolutionary science, Wilson’s greatest impact may be that radical idea he advocated for at the end of his life. Although it stood on the science he’s famous for, Wilson’s last gift is really about policy, humanity, and hope.

Half-Earth may sound like science fiction, but movements are under way to attempt to make it—or something like it—a reality. And if in a century, half the planet is in some sort of natural or regenerating state—with humans not shut out, but a part of the efforts to manage this Half-Nature—it will be due in part to Wilson relentless advocacy at the end of his life.

The Fateful Fish’s Fin

When E.O. Wilson was seven, growing up in Birmingham, Alabama, he was out fishing and a pinfish bit. He yanked on the line hard; the pinfish flew out of the water and a spine from its fin spiked into Wilson’s eye. The fish’s fin—arguably one of the most important fish fins in the annals of science—left Wilson blind in his right eye.

With his ability to see far afield was forever marred, Wilson turned his gaze on the little things that he could focus on. Instead of birds, mammals, or fish, he turned to insects and eventually ants, a lifelong obsession and love—and a pillar of all his scientific work.

Wilson started at the University of Alabama and then went on to Harvard, where he would teach for 46 years and do much of his ground-breaking research.

Tiny Islands

In the 1960s, when Wilson was in his thirties and a new professor at Harvard, he partnered with a brilliant mathematician and ecologist, Robert MacArthur, to develop an equation on how many species an island could hold based its size.

The theory, initially based on Wilson’s study of ant communities on Pacific Islands, argued that there was an equilibrium of species on islands, depending on the island’s size. This meant that every extinction on an island created chances for immigration of another species. Eventually, though, an island fills up—hits equilibrium. Not only do larger islands hold more species, but they do so at a rate that Robert MacArthur could actually calculate as the species-area relationship.

Wilson and MacArthur published their theory in a book in 1967—and then Wilson went out to test it in the field. Among a few tiny mangrove islands in the Florida Keys, Wilson, and then-student Daniel Simberloff, began by carefully surveying the insects on each islet. Then they fumigated the islands, wiping out all life. Next, they waited. It happened fast: Within just a year all the tiny islands had been recolonized to pre-apocalypse levels of biodiversity and then stabilized, into a kind of biodiverse equilibrium.

With these real-life results, the species-area equation rapidly became not only a foundation for ecologists working the lab, but for conservationists actively working to save species in the wild. It showed that not only was there an equilibrium of species on islands, but if islands shrink, they inevitably shed species.

You see, the only islands on Earth were no longer those standing in the ocean. Increasingly, the whole world was becoming “islands” of natural areas surrounded by human-dominated ones: a patch of tropical rainforest surrounded by city in the Mata Atlantica of Brazil, a national park of savanna encompassed by ranches and towns in Botswana, a long grass prairie on the side of a freeway in the U.S., a hill of forest in Malaysia with palm oil on every side. For all intents and purposes these environments were as much islands as those surrounded by salt waters.

Our natural world was being pulled apart, sundered into islands of habitat, surrounded by areas for human-use, in which most species could not survive long-term.

After his seminal work on biogeography, he turned to a budding new concept known as sociobiology. This new field attempted to explain animal behavior, especially complex social behavior like in Wilson’s favorite subject ants, via processes of evolution.

Wilson’s works, including numerous books, both furthered and popularized the study. And also led to much controversy. Wilson proposed one could apply the concept of sociobiology to ant, naked mole rats, and humans. Wilson argued that to some degree, at least, our evolutionary history—our genes—predicated our behavior and our role in society. And that society—whether the society of ants or humans—was driven by evolution. Through his work on sociobiology, he also developed the concept of “biophilia” arguing that humans had an innate—genetic—love of life, of biodiversity.

By the time of Wilson’s retirement from Harvard in 1996, it seemed he would be destined to be remembered for his landmark work on island biogeography and his daring ideas on sociobiology. But Wilson’s biggest contribution to our planet—both human and non-human alike—may have actually come in the last decade of his life.

Half Nature

“It’s been in my mind for years,” Wilson told journalist Tony Hiss in 2014, “that people haven’t been thinking big enough—even conservationists.”

What if the whole planet was an island? Just a single island, containing around eight million species—according to the most recent estimates—and trillions of living, breathing, consuming, loving, and dying entities. If the whole world is an island of breathtakingly beautiful habitats—from the hydrothermal vents replete with giant tube worms on the deep ocean mounts to the squeaking pikas found on Himalayan heights—then how could we ensure that in the Anthropocene, this age of Humans, we could still preserve the rest of life?

According to the theory of island biogeography, extinctions will occur when an island shrinks, i.e. habitat is destroyed. This is what’s happening today. Species are vanishing at a rate of 100 to 1,000 times the normal background rate due to humans destroying their habitat, among other impacts—overhunting, climate change and pollution, to name a few. And we don’t know how many extinctions the planet can tolerate before ecosystems start to wholly unwind.

To fight this global problem, Wilson turned back to the theory he developed with MacArthur in the 1960s. If Earth is an island and we protect only 10 percent of habitat—about where we are today—we lose half the world’s species. A mass extinction on par with some of the largest in the past. But if we protect half of the world’s habitat, then we retain around 80 percent of species—maybe more if we make certain to protect the most biodiverse regions, such as coral reefs and tropical rainforests. This would avoid the portents of mass extinction and ecological collapse that could send our civilization careening into disaster.

In 2016, E.O. Wilson published Half-Earth, after a term first coined by Hiss in 2014. Wilson didn’t invent the idea of protecting half the earth—it been bumping around conservation circles for a bit—but in his way as a master-synthesizer and one of the best science communicators of the last century, he actualized its potential.

The idea is beyond bold, some might even say crazy—but is in line with Wilson’s career of constant ambition and pushing boundaries.

It was pure Wilsonian.

A People’s Conservation

Wilson did not envision Half-Earth as a blanket of fortress conservation—a focus on strict protected areas that have a history of keeping local and indigenous people out—but rather a patch-work of various types of protections, many allowing for human activities and habitation.

“You don’t need to abrogate property rights and you don’t need to move anybody out,” Wilson told me in 2017.

Wilson envisioned Half-Earth as a flexible network of conservation areas of varying degree: some strictly protected areas, of course, but many modeled off the U.S.’s National Landmarks Designation, which works with local landowners and communities to protect landscapes that humans still live in. This could include other models of community conservancies, such as those that have proven so successful in parts of sub-Saharan Africa.

Wilson believed Half-Earth must also include Indigenous territories. He pointed out to me in 2016 that Indigenous groups “are often the best protectors” of their own lands. This has been borne out repeatedly in research that show Indigenous lands preserve biodiversity as well or even better than classic protected areas. In other words, the fight for conservation—and climate change action and a livable Earth—is unwinnable without Indigenous land rights.

“[Half-Earth] will protect Indigenous people who otherwise would find their way of life destroyed as more agriculture and human settlement come in,” Wilson added.

Indigenous people have long been at odds with conservationists, due to a brutal history of being pushed off their lands, often by force: The creation of Yellowstone, the U.S.’s first national park, led to the expulsion of indigenous people. But now, combining the strength of Indigenous land rights movement with conservationists could remake the world.

Currently, around 17 percent of the planet’s landmass in under some form of protection (just 12 percent in the U.S.), and a bit over seven percent of oceans. This means, of course, we have a long way to go before Half-Earth. But the idea doesn’t seem as wildly improbable as it did even five years ago when Wilson published his book.

30-by-30

A year ago, more than 50 nations committed to the “30-by-30” plan: A call to protect 30 percent of the planet’s land and oceans by 2030. This was a part of the so-called “High-Ambition Coalition”, created by the Marshall Islands in 2016, a loose formulation of nations pushing for keeping global temperatures from rising more than 1.5 degrees Celsius.

The nations who approved 30-by-30 include some of the world’s heaviest hitters, such as the EU, the U.K., Canada, Japan, and Nigeria (the most populous nation in Africa). Hyperdiverse nations like Colombia and Costa Rica (which is already near the 30 percent target) have also signed on. These nations are expected to 30-by-30 a global goal at the upcoming COP15 Biodiversity Summit scheduled to be held in Kunming, China in 2022, unless it’s postponed again due to Covid.

The US is also pursuing 30-by-30. The Biden Administration is currently looking at achieving the target not only by expanding protected areas, but also working with tribal lands and incorporating other definitions of conserved lands—such as sustainably-managed lands. In other words, the administration, like Wilson, is viewing conservation success as multi-faceted and open to a variety of approaches.

If the 30-by-30 pledge becomes a part of the global pledge, and if even more miraculously, we achieve that target in eight years (or even close to it), it would mean we’d be around half way towards Wilson’s Half-Earth. An idea that one could argue seemed insane just a decade ago, now seems if not probable, maybe, just maybe, possible.

And, it wouldn’t mean a world split between humans and non-humans, with walls on either side, but instead a world where space was more equally shared, tolerated, and tended. In much of the planet, humans would still be doing all of our human things. But on the other side, we’d be stewards—gardeners, restorers, sustainable hunters, fishers, hikers, ecosystem managers, and, most joyously, observers of all the beauty of this little planet we call Earth.

Some of us will spend our lives there, in that Half Nature, others our vocations, and some just visitors from time-to-time. But the benefits—from carbon sequestration to clean water to soil health to abundant life—would spillover to all.

“You know, everybody dreams of a hole in one,” Wilson told me in 2017 when I asked what he most wanted to be remembered for. “You dream of putting the ball over the fence, you dream of the $10 million lottery winning ticket—and so I dream that I could have had a major influence in moving global conservation ahead.”

That was the legacy Wilson hoped for. And we might just achieve it.

Related listening from Mongabay’s podcast: Wilson appeared on the podcast to discuss the most important environmental issues he felt we face as a society, listen here: