On April 16, 1896, a chartered steamer, the Croydon, embarked from Brisbane in Queensland on an American scientific investigation of the Great Barrier Reef—the beginning of an epic series of Pacific-Indian Ocean expeditions led by a 61-year-old American zoologist and mining millionaire, Alexander Agassiz. His young biologist assistant Alfred Mayor recorded that Agassiz would for the next 25 years “wander further and see more coral reefs than has any man of science of the present or past.”
Alex Agassiz was visiting the Great Barrier Reef to blow Charles Darwin’s theory of the origin of coral reefs out of the water, and his expedition marks the moment when Australia’s Great Barrier Reef was first catapulted into global prominence as part of a fierce debate engulfing the world’s leading geologists, marine scientists, and oceanographers.
It was odd for Darwin’s theory of coral reefs to be generating such heat so long after its drafting. It had been Darwin’s juvenile scientific achievement, scribbled 60 years earlier when voyaging around the world as a young gentleman’s companion on HMS Beagle, before he’d ever seen a coral reef. It was, he said, an act of pure deduction, based on seeing coral fossils within the rock strata of the Andes. It appeared that the mountain chains had been elevated gradually from the ocean floor by volcanic action over eons of time. Perhaps too, a corresponding subsidence had taken place on the bed of the Pacific and Indian oceans? This would explain a mystery that had long puzzled navigators and naturalists: How did these tiny coral “insects,” known to live only in shallow light-filled waters, build vast ramparts that rose up from the dark depths of the oceans?
If coral reefs grew in a ring pattern around the shallow fringes of volcanic pinnacles in the sea and these rocky islets were to subside at a pace that matched the reefs’ upward growth, they would create thick walls of dead coral with a living crust on top. Over many centuries this process would leave behind circular atolls or barrier reefs separated from the mainland by lagoonlike channels. Darwin’s subsidence theory was also strengthened over many years by the closer investigations of James Dwight Dana, a Pacific voyager-turned-Harvard geologist. Since then few scientists had challenged this simple and elegant theory—one that Darwin in his autobiography of 1876 regarded as “well established.”
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Darwin’s would-be coral reef conqueror, Alex Agassiz, was born at Neuchâtel, Switzerland, in 1835, son of the great naturalist Louis Agassiz, who later became a charismatic Harvard professor of zoology. But following the publication of Darwin’s On the Origin of Species in 1859, Louis Agassiz’s belief that species were God’s thoughts ordered in a beautiful “Plan of Creation” was derided by Darwinists around the world. By the 1870s, his increasingly strident and ineffectual attempts to snuff out Darwin’s theory of evolution cost him much scientific respect.
At the age of 13, Alex was sent to join Louis and his new wife, Liz Cary, in Boston after his mother, Cecile, died of tuberculosis. There, wrote Mayor, the boy developed a “reverence for his father [that] was almost a religion.” Witnessing Louis’ scientific humiliations at the hands of fellow Harvard professors proved agonizing. Yet Alex was determined to make his own way in life. Having graduated in engineering and zoology, he married a wealthy Bostonian, Anna Russell, in 1860. Six years later Alex surprised everyone by rescuing a struggling Michigan copper mine, which he miraculously turned into one of the largest and most prosperous in America.
Continuing to exercise his passion for marine biology, Alex also published a string of empirical papers on the taxonomy and embryology of echinoderms (starfish, sea urchins, sea cucumbers). Privately, he also admitted to a “general” acceptance of his father’s nemesis, Darwinian evolution.
In mid-December 1873, however, Alex Agassiz’s happy world collapsed. First, Louis Agassiz died suddenly on Dec. 14, after suffering a massive stroke. A few nights later Alex’s beloved wife, Anna, was diagnosed with severe pneumonia. Aged only 33, she was buried on Christmas Eve. Alex was too stricken even to comfort their three distraught sons. And as months and then years passed, Alex’s friends noticed permanent changes in his personality. The formerly gentle scientist became prone to bouts of explosive anger with students and employees alike.
In late 1876, as fragile as ever, Alex accepted an invitation to help a celebrated Scottish marine scientist, John Murray, sort through thousands of specimens of animals, plants, and seafloor deposits collected on the HMS Challenger’s three-year oceanographic expedition around the world. Alex became animated for the first time in years when Murray told him that billions of calcium skeletons from minute single-celled plankton rained down onto the ocean floor faster than they could be dissolved by the carbonic acid in seawater. Settling on rocky mounds pushed up from the ocean floor, this detritus gradually amalgamated into sedimentary limestone platforms. When these reached surface light, corals began to grow on top. Toward the windward edges, a patina of living corals fed on the wave-carried plankton, but those sheltered to leeward would starve and die, after which their calcium skeletons would dissolve in the seawater. Crescent-shaped atoll lagoons or canal-like barrier lagoons would thus be formed without any need for Darwinian subsidence.
Alex returned to America barely able to contain his excitement: “It is the first time since the death of my father and my wife that I have felt in the least as if there were anything to live for,” he wrote to a friend. Up to now he’d left issues like the origins of coral reefs to the geologists, but the scales had fallen from his eyes: “I never really accepted the theories of Darwin,” he confided to Murray. “It was all too mighty simple.” At last a wounded son had the chance to revenge his father’s humiliations.
In 1880, Murray presented his formal case against Darwin in Nature. He claimed to have seen archipelagoes in the Pacific with no signs of subsidence but strong evidence of elevated sedimentary platforms. Emboldened, Alex wrote to Darwin, predicting that future reef expeditions would confirm Murray’s results. Though ailing, Darwin didn’t miss the note of challenge and promptly countered with one of his own: “If I am wrong,” he wrote wearily, “the sooner I am knocked on the head and annihilated the better … I wish some doubly rich millionaire would take it into his head to have some borings made in the Pacific and Indian atolls and bring home some cores for slicing from a depth of 500 or 600 feet.” If Darwin were wrong, cores would show a shallow crust of coral succeeded by extensive, older, submarine rock. If he were right, the cores would reveal coralline limestone all the way down.
Alex’s decision to lead a crusade against Darwin was also fuelled by a new band of supporters. In England the Duke of Argyll and a trio of bishops accused “the Darwin faction” of mounting “a conspiracy of silence” and a “reign of terror” designed to stifle Murray’s theory and mask “errors as profound as the abysses of the Pacific.” Shifting their attacks away from the Origin of Species and toward Darwin’s theory of coral reefs was shrewd. The difficulty of proving Darwin’s reef theory made it seem vulnerable to demolition. In effect, the Argyllites elevated the coral reef problem into “one of the most prominent and explicitly controversial in science.” By overturning it they hoped to undermine the larger evolutionary cause.
This time around quiet Louis Agassiz’s son would lead the charge against the Darwinist horde. His banner would be scientific empiricism; his field, the coral reefs of the world.
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In 1896, Alex Agassiz put to sea to revenge his father, conquer Darwin, vindicate Murray, and unlock the secrets of Indo-Pacific coral reefs. Privately he would later concede that his first destination, Australia’s Great Barrier Reef, proved something of a disappointment. He’d mistakenly visited in April–May. As a result, the small American party faced two months of buffeting southeasterly trade winds that forced their ship to remain in harbor for all but three days. They managed only to inspect a fragment of the southern inner reef between Breaksea Spit and Lizard Island. Mayor reported that they gained two fleeting glimpses of the outer Barrier—“the grandest coral structure in the world”—but from “a respectful distance.”
Before setting off, Alex had studied every available Barrier Reef chart, explorer’s account, and scientific paper, including several recent analyses by Australian geologists who agreed that an extensive ocean floor subsidence had taken place during the Cretaceous period, some 65 million years earlier. This had broken up a large original Pacific continent, leaving Australia behind. Alex didn’t deny the subsidence, but disputed its connection with the present-day Barrier Reef, which he believed to be a modern production. Had the corals begun growing at that remote period, they would “have a thickness which should correspond to a depression of at least 2000 feet.” Such an unimaginable thickness of coral he thought too absurd to need refuting.
Alex claimed, moreover, that even his abbreviated investigation of the Great Barrier proved the essential correctness of Murray’s theory. Confirmation, he believed, came when exploring reefs at Hope Island, not far from Cairns. “Here,” Mayor recorded, “greatly to Mr. Agassiz’s joy he found the reefs so thin that he actually obtained specimens of the granite rock under which the coral grows. This settles the question that the reef is formed in the Murray manner and not in that suggested by Darwin.”
Believing he had already netted the greatest scalp of all, Alex next decided to investigate Fiji, using much the same team as before. This time, he arrived in mid-October when conditions suited reef viewing. His confidence swelled: “I shall give [the Darwinists] a dose they do not expect,” he wrote to Murray in triumph, “and the theory of subsidence will, I think, be dead as a doornail and subside forever hereafter.” Between 1899 and 1900, Alex added a procession of supposed victories by mounting expeditions to the majority of Pacific and Indian ocean reefs. So armed, he now claimed to be in a position to deliver Darwin a killer blow.
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When on March 26, 1910, Alex Agassiz died in his sleep, his old friend John Murray was saddened to hear that nobody could find the long-promised book rebutting Darwin’s theory of coral reefs. It had never been written.
In the end Charles Darwin’s theory of coral subsidence proved substantially correct, though it took technical advances in drilling and American war-chest money to demonstrate it. After American scientists exploded a series of nuclear tests at Enewetak Atoll in the Marshall Islands during the 1950s, they used high-power drills to cut through the atoll’s reef in order to investigate its resilience. Their deepest cores contained coral fossils that could only have grown in shallow waters. The drillers concluded that Enewetak’s coral reefs had begun to grow during the Eocene period, and for 30 million years scrambled upward on a sinking volcano, thickening as the lava subsided.
So young Darwin had been right all along; and Alex Agassiz had been too blinded by his personal obsessions to see it. Still, these same obsessions fueled the study of coral reefs all over the globe, thrust the Great Barrier Reef into the forefront of global scientific attention, and initiated new methods for investigating and understanding marine life. It was a legacy of which even squabbling scientists might have been proud.
Adapted from The Reef: A Passionate History—The Great Barrier Reef From Captain Cook to Climate Change by Iain McCalman, out now from Scientific American / Farrar, Straus and Giroux.