Hurricane Lizards and Plastic Squid

CHAPTER ONE

Nothing Stays the Same

All change in habits of life and of thought is irksome.

—Thorstein Veblen

The Theory of the Leisure Class (1899)

I heard them before I saw them, screeching and croaking from somewhere overhead like a pair of deranged roosters. The noise went on and on, and it struck me as preposterous that any sane person would want to keep one of these birds inside their house. Yet demand for the pet trade had helped transform the great green macaw from a commonplace species into an endangered species. I’d spent three years studying their main food source in what was once prime habitat, but to actually spot a macaw required two days of backcountry travel by bus, river launch, and finally, a motorized canoe. So when two birds suddenly launched themselves from a treetop and soared out over the river, I felt the thrill of a moment long anticipated, and I also knew immediately what made pet fanciers so willing to overlook all that racket and clamor. Even from a distance, the macaws’ brilliant green plumage shone in the sunlight, rippling with accents of crimson, chestnut, and bronze, and framed by wide blue wings, as if every color within view, from sky to river to rainforest, had been distilled and brought to life in feathers.

I watched with satisfaction as the birds crossed from the Nicaraguan to the Costa Rican side of the river and disappeared over a row of low hills. It seemed fitting to close out my research in Central America by glimpsing evidence of the avian resettlement it was designed to encourage. Though I hadn’t studied macaws directly, my work showed that almendro trees—whose almond-like nuts the birds rely upon—could persist and reproduce in patches of forest indefinitely, connected to one another over long distances by the busy pollination efforts of bees. That finding helped justify a new law protecting almendros throughout the lowlands of eastern Costa Rica, where cattle ranching and fruit production had left the rainforest divided by pastures, roads, and cropland. People hoped that if the right kind of trees remained, the macaws might return, repopulating old haunts from their stronghold to the north, in the large Nicaraguan nature reserve that I’d traveled so far to visit. As it turned out, that process was already well under way. In the years ahead, hundreds of birds would set off on the same flight I’d witnessed, crossing the San Juan River and heading south to once again make great green macaws a regular sight (and sound) in parts of Costa Rica. It was briefly held up as a conservation success story—the returning birds not only found food in almendros, they also nested and raised chicks in hollows within the trees’ massive trunks. But scientists soon realized that the fate of the macaws and their favorite tree was an even better example of something entirely different, and far more consequential.

Looking back, I see now that the phrase “climate change” did not make a single appearance in the many proposals, reports, and peer-reviewed papers associated with my almendro research. At the time, it didn’t seem relevant to such a specific and local biological study. But I did receive one suggestive hint along the way, delivered in an offhand comment from another scientist working out of the same field station. Her data showed how almendro trees responded to hot weather by increasing their rate of respiration, the process plants use to get oxygen to their cells. In a sense, the trees were panting. This and other signs of stress didn’t bode well in a warming world, and when climate modelers later began making predictions about Central America, it was clear that almendros were in a tight spot. “The trees you studied will be gone by the end of the century,” one expert told me, explaining how the species’ survival depended on shifting its range upward in elevation to find the temperatures it preferred. Suddenly, the most important result of my work was something I’d published almost as an afterthought—the fact that large fruit bats could disperse almendro seeds in leaps of a half mile (eight hundred meters) or more. Would that be far enough and fast enough to beat the heat? Would the bats be moving in the right direction? Could almendros even establish themselves in higher forests already crowded with trees? And what did all this mean for the macaws, who were expected to simply fly north to cooler climes, unconstrained by the slow pace of seed dispersal? Instead of a tidy relationship between parrots and trees, the macaw-almendro story has become yet another case study in uncertainty, symbolic of a planet in flux.

As a biologist, perhaps I shouldn’t have been surprised by the sudden plight of almendro trees. After all, change lies at the heart of evolution, and evolution is the heart of biology. The very word evolve comes from a Latin verb meaning “to unroll,” and every organism is a product of that constant motion. Species wheel into existence, adapting and often giving rise to new things along the way, before eventually winking out as the world moves on around them. Even if almendros fail to reach the foothills and disappear altogether, that would be perfectly normal; extinction is the fate of all species. I knew this, but still found it head-spinning to think that my giant study trees—some measuring ten feet (three meters) in diameter—might soon be gone. It was more than sentimentality or simple surprise. Resistance to change is considered a hallmark of the human psyche. Experts link it to our instinctive sense of comfort and safety in the familiar, combined with a need for social cohesion and consistency. The result is a common sentiment neatly captured in the words of cartoon everyman Homer Simpson: “No new crap!”

FIGURE 1.1. The great green macaw is the largest parrot in Central America, where its relationship with almendro trees is now uncertain. P. W. M. Trap, Onze Vogels in Huis en Tuin (1869). Biodiversity Heritage Library.

I certainly wasn’t the first person unsettled by the idea of a changing environment. For most of human history, people preferred to dismiss the notion entirely and regard the natural world as something immutable. Certainly, there were seasons and the occasional drought or flood, but the land and the seas and the creatures within them were fixed. Greek philosopher Parmenides went so far as to prove that change was impossible. Nothing comes from nothing, he argued, nor can anything come from what already exists, because, “what is… is.”

Aristotle found some wiggle room in that argument by suggesting that objects might change form so long as their underlying essence persisted. An acorn could grow into an oak tree, for example, or bronze could be melted and cast to form a statue. This accounted for the obvious processes of change encountered in daily life, without challenging the idea of nature as something absolute. Aristotle also proposed organizing the natural world into a strict hierarchy, with what he perceived as simpler forms like plants near the bottom and more sophisticated things like animals (and Greek philosophers) on top.

Later scholars embraced and embellished this notion, finding rungs on the ladder for any newly discovered species, as well as things like precious metals, planets, stars, and even various types of angels. The paradigm held for nearly two thousand years, and it was echoed in the taxonomic ranking system developed by that great cataloger, Carl Linnaeus, who noted in 1737 that all true species “have been assigned by Nature fixed limits, beyond which they cannot go,” and that their number “is now and always will be exactly the same.” Even as Linnaeus wrote those words, however, new ideas were already shaking the foundations of the old worldview. Fittingly, the evidence that change was not only common, but in fact a prime mover in nature, came from stone, a substance that had always been placed at the very bottom of Aristotle’s hierarchy.

Few readers are thought to have made it through all 1,548 pages of James Hutton’s 1795 opus, Theory of the Earth, not to mention its 2,193-page companion, Principles of Knowledge. But even the Scotsman’s daunting wordiness couldn’t obscure the power of his central geological theme—that the bedrock of continents and islands formed from constant erosion and sedimentation, cemented and then uplifted by the heat of the Earth. Instead of a static landscape, he proposed an ongoing “succession of worlds,” continually unfolding over huge spans of time. It was a radical thought, but one supported by ample evidence then coming to light in the mine shafts proliferating across Great Britain. Demand for coal and metals to feed the Industrial Revolution had inadvertently opened a window into deep time, exposing layers of bedrock with ancient stories to tell. Some contained marine fossils, bolstering Hutton’s notion that rocks—even those found high up on hills and mountains—had formed from ocean sediments. Other stones held the remnants of strange plants or unfamiliar animals, suggesting that life, as well as landscapes, had looked quite different in the distant past. This raised an obvious and troubling question: Where had those species gone?

FIGURE 1.2. This sixteenth-century illustration depicts the natural world as an immutable “Great Chain of Being,” ascending from rock and soil to plants, animals, and humanity. Images of heaven and hell (and their inhabitants) frame the scene above and below. Diego Valadés, Rhetorica Christiana (1579). Getty Research Institute.

Extinction was a purely hypothetical concept until French naturalist Georges Cuvier started thinking about elephants. Shortly after Hutton upended the idea of permanence in geology, Cuvier took aim at its biological counterpart. His meticulous examination of fossil elephant teeth showed that various mastodons and woolly mammoths were distinctly different—not only from one another, but from all living elephant varieties. He called them lost species, and because elephants are enormous and impossible to overlook, it was hard for doubters to argue that mammoths and mastodons were still out there somewhere, waiting to be noticed. (Interestingly, mastodon enthusiast and third US president Thomas Jefferson suggested just that, instructing members of the 1804 Lewis and Clark Expedition to scour the American West for animals that “may be deemed rare or extinct.”) Cuvier spent the rest of his career driving the point home, describing extinct forms of everything from turtles and sloths to pterodactyls. But one of his most lasting contributions was the observation that species didn’t just wink out one by one. Sometimes whole communities disappeared from the fossil record all at once, replaced by a vastly different group of organisms in shallower, younger layers of rock. He famously held this up as a challenge to Hutton’s ideas about gradual geological change, arguing that ancient landscapes (and all their inhabitants) had instead been repeatedly destroyed by a series of floods or other catastrophes. As a general theory, known as catastrophism, it was eventually debunked. Aside from the occasional earthquake or volcano, most processes in geology do indeed play out slowly, just as Hutton had suggested. But Cuvier’s fossils showed that extinction events could at least occasionally be abrupt and widespread—the first indication that the natural world was capable of rapid change. It was an idea that the greatest naturalist of the next generation would always struggle to reconcile.

Hutton’s and Cuvier’s theories challenged religious norms as well as scientific dogma, and decades of contention followed. Many scholars countered with biblical arguments—if rocks contained traces of marine life, then they must have formed during the Flood, and any unfamiliar fossils were simply creatures that hadn’t made it onto the ark. Others accepted the concept of ancient worlds, but offered different theories about rock formation, fossil origins, and what caused the transition from one era to the next. Such debates fascinated the young Charles Darwin, who devoted much of his early career to geology. He called himself a “zealous disciple” of the Hutton viewpoint, as popularized and expanded upon by the great nineteenth-century geologist (and Darwin’s good friend) Charles Lyell. Darwin collected thousands of fossils and rock specimens during his voyage on the Beagle—often at the expense of zoological pursuits—and looked forward to visiting the Galápagos Islands not for their finches, but because “They abound with active Volcanoes.” He later drew on fossil evidence to support his thinking about species formation, and so did Alfred Russel Wallace. Joint publication of their papers on evolution by natural selection in 1858 (and Darwin’s The Origin of Species the following year) did for biology what Hutton had done for geology—embracing change as fundamental, and giving it a convincing mechanism. But both men considered the pace of that change to be slow and incremental, neatly complementary to the emerging consensus on gradual geological forces like erosion and sedimentation. More than a century would pass before biologists began to grasp how quickly things could happen—in the environment, in evolution, and in the critical ways those forces interact. Once again, the first insights came not from studying modern creatures, but from an understanding of stone, fossils, and vast spans of time.