Leonardo’s Mountain of Clams and the Diet of Worms (13 page)

But all human beings belong to a single fragile species, a biological unity too much divided by the worst emotional traits of our common nature. Separate the stones from the snakes, but let Emmanuel Mendes da Costa, a Jewish stranger in a strange land, shake hands with his Mad King George—for then, perhaps, “they shall not hurt nor destroy in all my holy mountain,” made,
no doubt, of the genus
Granita
, from the Italian for grain, to signify all the bits and pieces of diverse minerals that come together to form this hard rock of unity.

DARWIN’S AMERICAN SOULMATE: A BIRD’S-EYE VIEW

I
HAVE LONG CONSIDERED
A
BRAHAM
L
INCOLN AS
C
HARLES
D
ARWIN
’
S
American soulmate—for they were born on the same day, February 12, 1809. But perhaps the accidents of joint beginnings should not define a concept of such intimacy. If soulmates must be linked more tightly by their active choices, then Darwin’s American alter ego can only be his fellow
scientist James Dwight Dana (1813–1895)—geologist, biologist, longtime professor at Yale, and surely America’s preeminent indigenous natural historian of the nineteenth century. (Louis Agassiz, the other obvious contender, was born in Switzerland and did his important scientific work in Europe before coming to Harvard University in the late 1840s.)

Dana and Darwin never met personally—though
they both expressed a warm desire to do so in their numerous letters. But their careers and interests ran in intricate, almost eerily parallel courses. Both men had their scientific baptism in a long sea voyage around the world—Darwin on the
Beagle
from 1831 to 1836, and Dana on the Wilkes expedition of 1838–1842, young America’s greatest international scientific journey, dispatched primarily
to assess whaling prospects in the southern oceans. Both men, similarly inspired by their travels, then built their scientific careers on the same two subjects.

Darwin’s first scientific book, published in 1842, presented a correct theory on the origin of coral atolls by subsidence of a central island, with continued upgrowth of living coral at the edges. Dana also became fascinated with corals
when he visited Pacific reefs. In 1839, while ashore in Sydney, Dana chanced upon a description of Darwin’s ideas in a local newspaper. With this inspiration, Dana produced the other great nineteenth-century work on coral reefs—
Corals and Coral Islands
—substantially supporting Darwin’s “subsidence theory,” but based on far more extensive observation than Darwin had been able to make. In the preface
to the second edition of his book on coral reefs, Darwin wrote:

In a second parallel, both Darwin and Dana devoted their major technical work in zoology to the taxonomy of the same group of organisms—the crustacean arthropods. Darwin published four volumes between 1851 and 1854 on the oddest of crustacea, the barnacles. Dana based fourteen years of research on specimens collected by the Wilkes expedition, and published his finest
work in 1852—two volumes on the taxonomy of crustaceans.

In fact, Darwin’s barnacles inspired the first personal contact between the two men in 1849, when Darwin wrote to ask if he might borrow specimens collected by Dana’s expedition. (Thus, the striking similarity of their careers had developed without any direct mutual encouragement.) Darwin wrote, rather formally:

Dana replied, warmly but sadly, that he would be personally delighted to do so, but had neither possession nor authority over the specimens. Darwin understood,
and wrote Dana a long letter of praise for his work, noting: “You cannot imagine how much gratified I have been that you have to a certain extent agreed with my coral island notions.”

A warm epistolary friendship ensued. Darwin wrote three years later, in 1852:

(Darwin knew himself well. After sailing around the world and returning to England, he never again left his island home; he never even crossed the English Channel!)

The next year, Darwin enthused over Dana’s volumes on crustacea, just published:

Despite this effusion of warmth and mutual support,
Dana and Darwin inevitably parted company on the great issue that would define their time (and ours)—evolution itself. As I shall document later, Dana did eventually succumb to the inevitable in the mid-1870s, but his late support for evolution always remained strictly limited, clearly grudging, and only pursued as a necessary compromise to save as much as possible of his unaltered worldview. But
Dana remained a staunch, if always cordial, opponent of evolution throughout the great debates of the 1860s, the defining decade after Darwin published the
Origin of Species
in 1859.

Darwin sent Dana a copy of the first edition, but Dana’s health had broken, and he did not read the book until 1863. Nonetheless, Dana could not avoid the issue in publishing the first edition of his most famous
work in 1862—the
Manual of Geology.
While stating his opposition in the book, Dana also thought that he owed his epistolary friend a personal explanation. So he wrote to Darwin on February 5, 1863: “I hope that ere this you have the copy of the
Geology
(and without any charge of expense, as was my intention). I have still to report your book unread; for my head has all it can now do in my college
duties.”

Dana then spelled out his major objections, all paleontological, in a series of three points. Dana’s arguments show that he based his opposition upon his personal definition of evolution as a necessarily progressive and gradual process. If evolution were valid, Dana claimed, then the history of life would have to proceed by slow and steady transformation from simple to complex forms
in each lineage. Dana then listed his objections:

Dana had cited a set of highly traditional objections—lack of transitional forms, first geological appearance of advanced rather than primitive members of a lineage, and mass extinctions—and Darwin rebutted them all (not entirely successfully, as later history would show) by arguing
that a woefully imperfect fossil record had rendered a truly gradual and progressive history of life in this deceptive manner. Darwin did feel that he owed Dana a personal reply, and he wrote back with his usual rationale on February 20, 1863—just two weeks after Dana had dated his letter, and not bad for sea transport of mail during the Civil War:

Then, in the only hint of rancor that I have ever detected in their correspondence, Darwin upbraids Dana for stating these objections without reading his book—though he quickly falls back into his usual geniality, and also assures his friend that he only
felt aggrieved because Dana’s opinion carried so much weight:

The personal and intellectual drama of Darwin and Dana provides the main subject for this essay, but I also write to illustrate a broader theme in the lives of scholars and the nature of science: the integrative power of worldviews (the positive
side), and their hold as conceptual locks upon major innovation (the negative side). I will argue that Dana was not benighted, stupid, or particularly stubborn. Rather, he maintained a consistent, well-articulated, and clearly coherent theory of God and life—a worldview that just didn’t contain any logical space for a Darwinian concept of naturalistic evolution. One does not (and probably should
not) surrender the system of a lifetime for one apparently errant bit of information. If we can do so at all, we will surrender such sources of succor and consistency with the same feelings that we experience when we leave a natal home or a first great love—slowly, sadly, prayerfully, and, above all, with deep affection and respect.

The issue of when to hold firm as suggestions of factual collapse
accumulate, and when to plunge with abandon into the breach, defines the most interesting and important dilemma of intellectual autobiography—for this decision defines the borderline between competence and genius, or between sensibility and crankiness. In some crucial sense, the geniuses of history are people who know when to plunge and how to create the instruments of successful assault and
replacement. But we must also remember that probably 99 percent of personal plunges fling potential heroes into whirlpools of error and erasure from history. Still, the message of these failures should not inspire calls for sticking with the tried and true at all costs—or else the earth would still occupy the center of a small universe, and people would still be the manufactured incarnations of a
divinely ordained perfection. Most people, including the most polished intellectuals of every generation, never dare to take the plunge. This phenomenon of psychology and society produced the old cliché, usually attributed to the nineteenth-century German physicist Ernst Mach, that new theories only triumph fully when the old guard dies off.

Dana’s conservative, and ultimately superseded, worldview
rested upon two central convictions that made Darwinian evolution impossible (not so much factually wrong as literally inconceivable within such a system). First, Dana was as pure a Platonist as nineteenth-century biology ever produced. He based his zoological ideas firmly on the old concept of “type”—an idealized form for each group of animals, with variation among individuals of a species
as accidental departures from ideal propriety, and variation among species as organized sequences obeying “laws of form” that expressed the thoughts and plans of divinity. (Agassiz, Dana’s equally Platonic colleague, declared taxonomy to be the highest science, for each species represents a divine idea made flesh, and the arrangement of species therefore expresses the structure of divine thought.
By understanding the system of order among species, we therefore achieve our closest insight into the character of God’s mind.)

Second, Dana viewed the entire geological history of the earth and life as one long, coherent, and heroic story with a moral—a tale of inexorable progress, expressed in both physical and biological history, and leading, inevitably and purposefully, to God’s final goal
of a species imbued with sufficient consciousness to glorify His name and works. The physical earth, according to Dana, developed through time with the same gradualistic progress that defined life’s history. By following three major trends—the emergence of more and more land from the sea, the purification of the atmosphere, and progressive global cooling with consequent increase in climatic diversity
by formation of zones from poles to tropics—the earth became more and more suited to the successively higher forms of life that God created in each new episode of progress. For inhabitants of the land must be ranked “higher” than denizens of the sea; pure air inspires healthy complexity (slithering reptiles in murky swamps versus sinewy mammals on the bright plains); and cooler climates require
such advances as warm-blooded metabolism. Dana wrote in his
Manual of Geology:

Lest anyone be tempted to read the sequence of successive creations, each with increasing excellence, in an evolutionary
manner à la Darwin, Dana always took pains to state that such a history could only record the direct actions of a loving God with a goal in mind. Dana wrote in 1856: