Ethan Linck

Birds, Whiskey, and the Modern Evolutionary Synthesis: Ernst Mayr in the Solomon Islands


ISSUE 59 | TAXONOMY | DEC 2015

Near the end June in 1929, a 25-year old German ornithologist named Ernst Mayr was sitting in a hut in New Guinea, skinning and stuffing birds, when he received a telegram. Carried by a Papuan runner, it was a decidedly unlikely event: at the time, New Guinea was almost unimaginably remote, and Mayr had been out of contact with his mentor at the University of Berlin for nearly a year. But the telegram’s contents proved to be as significant as its delivery was improbable. At the urging of his advisor, Dr. Stresemann, Mayr was to take the first steamer down the coast and board the freight schooner France, assuming duties as the ornithologist for the American Museum of Natural History’s Whitney South Seas Expedition. The Whitney Expedition’s own ornithologist had recently taken ill, the telegram explained, leaving the leader only with a gaggle of Yale college seniors who “knew nothing about birds.” Mayr followed Stresemann’s orders, and boarded the France from the island port of Samarai. He spent the next nine months building a collection of bird specimens from the Solomon Islands -- and the subsequent decade using this collection to become one of the principal architects of the modern evolutionary synthesis, filling the lingering gaps in Darwin’s theory of evolution by natural selection.

How did shooting and skinning birds in an obscure corner of the South Pacific lead to one of the 20th century’s major scientific achievements? The Solomons spray like emerald teardrops south of the equator and nearly a thousand miles northeast of Australia, forming the geographic center of the region known as Melanesia (a name alternatively attributed to its rain clouds and its black-skinned inhabitants). Comprised of over 1000 islands, the archipelago ranges in size from tiny coral atolls to towering mountains rising 7000’ above the sea. At the time, they were notorious for their violent, cannibalistic inhabitants. As one British colonial officer put it when Mayr requested permission to visit the interior of Malaita: “I give you a 50-50 chance to come back alive.” Nor were they amenable to field biology’s more prosaic concerns. The France, an old copra (coconut meat) freight schooner, was insufferably hot and lacking toilets; Mayr himself eventually came down with a case of dengue fever. In a later interview, Mayr claimed the redeeming feature of the Solomons were its simple pleasures: “I must say I drank more whiskey in those nine months in the Solomon Islands than I ever have since in the rest of my life.”

The upside to these difficult conditions was that Mayr became the first western scientist to comprehensively document the bird life of the region, discovering in the process patterns of geographic variation that would inform his later theories. From Samarai, the France sailed northeast, visiting in sequence the islands of Choiseul, San Cristobal, and Malaita. Biologically, these relatively large islands are an intriguing intermediary between the overwhelming biodiversity of New Guinea and Australia and the strange, depauperate floras and faunas of the Pacific’s more isolated island groups. Mayr’s collections on these islands documented populations of closely-related birds that provided a spectrum of morphological divergence, from nearly imperceptible differences in plumage to dramatic differences in size and bill shape. The greatest differences were found on islands separated by a significant ocean channel, while the smallest differences were found between islands in the same lagoon.

From this observation, Mayr began to formulate a theory that that populations of birds and mammals in isolation from one another slowly accumulate differences, through the evolutionary mechanisms of natural selection, genetic drift, and mutation. Eventually, these differences become significant enough that populations can no longer interbreed, which he considered the benchmark by which different species are defined. In hindsight, these two interrelated ideas (now known as the theory of allopatric speciation and the biological species concept) seem intuitive, even obvious. But at the time, their impact was dramatic. Mayr had finally provided a convincing explanation of how different populations of the same species might become two. And at a time when the philosophical concept of a species was widely considered arbitrary, he formulated an elegant explanation for how they were delimited and why they were a biologically meaningful unit of organization -- why when he presented specimens from 137 named species to Melanesian Islanders, they had 136 names of their own.

At the end of the expedition, thoroughly tired of the tropics, Mayr sailed the 7 weeks back to Europe. He then promptly emigrated to the United States to take a job at the American Museum of Natural History, curating his new collection. A decade later, his first book was published, Systematics and the Origin of Species from the Viewpoint of a Zoologist, which became one of the seminal texts of the modern evolutionary synthesis. Today, Mayr’s contributions are widely taught and remain highly influential. But while his illustrious past as a field biologist is often mentioned, the region and organisms he studied are usually relegated to a footnote.

Given Mayr himself claimed the journey "had an impact on my thinking that cannot be exaggerated," it’s a striking contrast to the ubiquitous story of Darwin’s time in the Galápagos. Perhaps the reason for this discrepancy lies in the absence of a single example of his ideas as illustrative as Darwin’s finches and their varied bills. Instead, Mayr’s specimens at the American Museum are from taxonomic groups with unfamiliar names and discongruous patterns of variation: birds like fantails, white-eyes, and monarchs, whose features display a wide spectrum of divergence across islands. What these specimens lack in familiarity and shared patterns, though, they make up for by capturing the complexity of evolution and its paradoxical blend of chaos and elegance. It’s a fitting tribute to the ideas of the biologist who collected them, and the legacy of his time in the South Pacific.