The Tangled Tree: A Radical New History of Life. David Quammen
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It came back into fashion during the late nineteenth century, when the general idea of evolution gained acceptance but the crucial details of Darwin’s particular theory, offering natural selection as the primary mechanism, were widely rejected. Natural selection just seemed too mechanistic, too stark and unguided, and many evolutionists found it unpalatable. This situation went on for decades—the world accepting Darwin’s idea of evolution but not his explanation of how it occurs—though only historians remember that now. Lamarckism became neo-Lamarckism and seemed a less nihilistic alternative. It has continued to linger as a dubious but ineradicable notion—embodied in that single tenet, the inheritance of acquired characteristics—enjoying small surges of reconsideration even down to the present day.
But that single tenet was never Lamarck in totality. He had other ideas, some even worse. He believed in spontaneous generation. He disbelieved in extinction, at least as a natural process. He argued that “subtle fluids,” surging through the bodies of living creatures, helped reshape them adaptively.
In one of his earlier botanical works, before the shift to animals and the epiphany about evolution, Lamarck had arranged plants in what he called “the true order of gradation”: from least perfect and complete to most, ascending along an old-fashioned ladder of life. He matched that with a separate ladder for animals, a “counterpart” arrangement, showing an ascending series of forms: from worms, through insects, through fish and amphibians and birds, to mammals. Neither of those ladders hinted at divergence from common ancestors or transformation. But in the 1809 book Philosophie Zoologique, he included a different sort of figure, subtle yet dramatic, depicting animal diversity. It was a branched diagram, descending down the page, with major animal groups connected by dotted lines, like one of those connect-the-dots games for kids on the paper placemats at a pancake house. Connect the dots and discover that the secret shape is … an airplane! Or … an elephant! Or … George Washington’s head! In Lamarck’s dotted figure, the secret shape was a tree.
Lamarck’s tree of dots, 1809.
Birds sat perched on a branch divergent from reptiles. Insects had diverged from the main trunk before it yielded mollusks. Walruses and other marine mammals lay farther along that trunk, beyond which still other branches led to whales, then to hoofed mammals, and finally to all other mammals. Wrong though it was about the particulars, and despite being upside down, this figure marked an important transition in scientific thought. Scholars tell us that it was the earliest evolutionary tree.
Edward Hitchcock stands as a counterpoint to Lamarck, with that first evolutionary tree, in that Hitchcock offered a last pre-evolutionary tree in the decades before Darwin changed everything. In fact, Hitchcock presented two separate trees of life, one for animals, one for plants, in his 1840 book Elementary Geology, which became a successful and often-reprinted text in the mid-nineteenth century. Hitchcock’s trees were also innovative—among the first based on deep knowledge of fossils, not just close observation of living creatures. He called his illustration a “Paleontological Chart,” and what it shows is diversification of the animal and plant kingdoms charted against geological time, from the Cambrian period (beginning about 540 million years ago) to the present.
Hitchcock’s trees weren’t classically tree shaped, spreading outward into a canopy like a maple or an oak. Each of the two, the one for animals and the one for plants, looks more like a windbreak of tightly placed Lombardy poplars grown to maturity along a roadway. The base of each windbreak is a thick, solid trunk from which rise slender stems, fluffy with foliage but without much branching as they ascend. Vertical, parallel, they seem independent: crustaceans, worms, bivalves, vertebrates. The vertebrate stem does branch into several shafts. The shaft leading up to modern mammals culminates in the word Man, atop which sits a regal crown adorned by a cross.
The crowned “Man,” with its cross, tells us what we need to know about Hitchcock’s sense of hierarchy in the living world. He grounded his geology firmly within the tradition known as natural theology, meaning science purposed to illuminate the power and wisdom of God as creator of all, with humans as the culmination of that divine creativity. He was a devout, driven New England Yankee, and his “Paleontological Chart” reflected his view of humans as the apogee of creation, as well as his findings in geology.
Hitchcock was born to a poor family in Deerfield, Massachusetts, his father a Revolutionary War veteran and a hatter by trade, with debts and three sons, who found just enough money to see his boys through primary school and some time at the local academy. After that, as Hitchcock recalled, “nothing was before me but a life of manual labor.” He balked at the idea of apprenticing as a hatter, to his father, or in any other trade. Instead he worked on a farm—it was rented land, cropped by one of his brothers—for a period that stretched on so long, or what felt like so long, that later he claimed not to remember how many years. With his free time, especially rainy days and evenings, young Edward studied science and the classics. Ambitious and hungry, he thought he was preparing himself for Harvard. Under the influence of an uncle, he took up astronomy. Then came the great comet of 1811, a celestial passerby that reached its peak of brightness in the north sky during autumn that year, when Hitchcock was eighteen. He borrowed some instruments from Deerfield Academy and spent night after night measuring its progress. “I gave myself to this labor so assiduously that my health failed,” he wrote later.
The health crisis brought on a religious conversion: from Unitarianism, into which he had drifted, back to the Congregationalism of his father. That passed for a drastic rethink in Edward Hitchcock’s life. In lieu of Harvard, he returned to Deerfield and somehow got hired, at age twenty-three, as principal of the academy. Then he studied for the ministry, was ordained, and became pastor of a Congregationalist church in Conway, Massachusetts, just up the road from Deerfield. Throughout these years and for the rest of his life, Hitchcock remained an invalid in self-image if not bodily, obsessed with his own fragility, continually complaining that he felt death nearby, although he lived to be seventy. One scholar, having looked into his life and work, called him “a hypochondriac of the first rank.”
Hitchcock’s “Paleontological Chart,” 1857 version.
Conveniently for his scientific career,