Thursday, August 11, 2011

Darwin: serial plagiarizer or revolutionary genius?

Stephen Jay Gould once joked that “precursoritis" (or should it be "precursorism") is the bane of historiography. Nonetheless, it is clear that there were precursors to Darwin in describing natural selection and other components of his theory of evolution.

In 1941, Conway Zirkle wrote a remarkable (and long) paper Natural Selection before the "Origin of Species" (available in full via Google books) in which he collated and discussed over two dozen descriptions of natural selection and associated ideas that pre-dated Darwin.

Although most of these earlier authors lacked Darwin’s clear conception of the implications of natural selection for the origin of species, some of their passages are strikingly prescient of Darwin’s ideas. Take, for example, this passage from French freethinker Jean-Jacques Rousseau (1712–78):

… children, bringing with them into the world the excellent constitution of their parents, and then confirming it by the same exercises which first produced it, would thus acquire all that strength and vigour, of which the human frame is capable. Nature in this case treats them exactly as Sparta treated the children of her citizens: those of them who came well formed into the world, she renders strong and robust, and destroys all the rest...

Or this passage from the German philosopher Johann Gottfried Herder (1744–1803):

In short, every species extends its possession of the Earth in proportion to its capacity, cunning, strength, or courage… the whole creation is at war, and the most opposite powers are found so close to each other… Each strives with each, as each is pressed upon; each must provide for his own subsistence, and defend his own life. Why acts Nature thus and why does she thus crowd her creatures one upon another? Because she would produce the greatest number and variety of living beings in the least space, so that one crushes another,and an equilibrium of powers can alone produce peace in the creation.

In the Temple of Nature, Charles Darwin’s grandfather, Erasmus Darwin provides a poetic description of the Struggle for Existence, culminating in a graphic rhyming couplet:

In ocean's pearly haunts, the waves beneath
Sits the grim monarch of insatiate Death;
The shark rapacious with descending blow
Darts on the scaly brood, that swims below;
The crawling crocodiles, beneath that move,
Arrest with rising jaw the tribes above; 60
With monstrous gape sepulchral whales devour
Shoals at a gulp, a million in an hour.
—Air, earth, and ocean, to astonish'd day
One scene of blood, one mighty tomb display!
From Hunger's arm the shafts of Death are hurl'd,
And one great Slaughter-house the warring world!

While in Zoonomia he obliquely references Sexual Selection and Natural Selection:

The birds, which do not carry food to their young, and do not therefore marry, are armed with spurs for the purpose of fighting for the exclusive possession of the females, as cocks and quails. It is certain that these weapons are not provided for their defence against other adversaries, because the females of these species are without this armour. The final cause of this contest amongst the males seems to be, that the strongest and most active animal should propagate the species, which should thence become improved.

Two other early descriptions of natural selection have been unearthed since Zirkle’s paper. One comes from a densely written inaccessible book (Principles of Knowledge: see review here) by one of Darwin’s heroes, the geologist James Hutton, who rejected evolution of species, but described natural selection:

If an organised body is not in the situation and circumstances best adapted to its sustenance and propagation, then, in conceiving an indefinite variety among the individuals of that species, we must be assured, that, on the one hand, those which depart most from the best adapted constitution, will be most liable to perish, while, on the other hand, those organised bodies, which most approach to the best constitution for the present circumstances, will be best adapted to continue, in preserving themselves and multiplying the individuals of their race.

The second comes from an unlikely sourceNatural Theology (1809), where William Paley (the irritant that gave rise to Darwin's pearl) proposed natural selection, only later to reject it:

There is another answer which has the same effect as the resolving of things into chance; which answer would persuade us to believe, that the eye, the animal to which it belongs, every other animal, every plant, indeed every organized body which we see, are only so many out of the possible varieties and combinations of being, which the lapse of infinite ages has brought into existence; that the present world is the relict of that variety: millions of other bodily forms and other species having perished, being by the defect of their constitution incapable of preservation, or of continuance by generation.

Charles Darwin acknowledged the role of earlier thinkers such as Geoffrey St. Hilaire in very first edition of the Origin. He also clearly drew inspiration from agriculturalist Sir John Sebright, who he cites several times for his work on breeding. However, Darwin fails to mention in publication a passage penned by Sebright in 1809
The greatest number of females will, of course, fall to the share of the most vigorous males; and the strongest individuals of both sexes, by driving away the weakest, will enjoy the best food, and the most favourable situations, for themselves and for their offspring. A severe winter, or a scarcity of food, by destroying the weak and the unhealthy, has had all the good effects of the most skilful selection.
even though Darwin alluded to it in his C notebook of1838:
Sir J. Sebright — pamphlet most important showing effects of peculiarities being long in blood.++ thinks difficulty in crossing race — bad effects of incestuous intercourse. — excellent observations of sickly offspring being cut off so that not propagated by nature. — Whole art of making varieties may be inferred from facts stated

Two others were credited only in later editions of the Origin for their prior descriptions of natural selection. William Wells was a Scottish-American physician who described the role of natural selection in the evolution of humans in the appendix to an essay on dew published in 1818, while Patrick Matthew was a Scottish fruit grower who proposed natural selection as mechanism of evolution in his On Naval Timber and Arboriculture (1831) over a quarter-century before Darwin and Wallace.

So, it is clear that Darwin was not the first to propose all the ideas that made up later came to be known as the Darwinian Theory of Evolution. However, any attempt to detract from his revolutionary achievements by arguing that he was simply a serial plagiarist or intellectual scavenger is as senseless as claiming that Shakespeare was a second-rate playwright merely because he reused some old existing plotlines!!

It was Darwin’s genius to weave many disparate ideas (such as variation under domestication, Malthusian population pressure and the oddities of biogeography) into a unique combination that is still largely thought to be accurate today, while other combinations of similar concepts, for example, Lamarck's or Spencer's theories of evolution, have been abandoned.

In addition, Darwin was able to articulate these ideas, and the evidence for them, with such unprecedented clarity and forcefulness that within a few short years most naturalists and much of the wider society had come to accept biological evolution as a fact, proven beyond reasonable doubt. Furthermore, there is an abundant documentary evidence trail to show that Darwin generally did not rely on precursors in his thinking, and where he did, he acknowledged it.

Peter Bowler, Professor of History of Science at Queen’s University Belfast makes the point forcefully in his book Evolution, the History of an Idea:
“Simple priority is not enough to earn a thinker a place in the history of science: one has to develop the idea and convince others of its value to make a real contribution. Darwin's notebooks confirm that he drew no inspiration from Matthew or any of the other alleged precursors.”
Darwin’s own son Frank Darwin made a similar point in the first Galton Lecture in 1914 (albeit moaning about Weismann gaining credit when Francis Galton had priority over on the continuity of the germ cell) :
“In science the credit goes to the man who convinces the world, not to the man to whom the idea first occurs. Not the man who finds a grain of new and precious quality, but to him who sows it, reaps it, grinds it and feeds the world on it”
The last word on this subject should go to Darwin himself, who in an 1860 letter to Rev. Baden Powell (father of the scoutmaster) states that
"No person, not even the most ignorant, could suppose that I meant to arrogate to myself the origination of the doctrine that species had not been independently created. The only novelty in my work is the attempt to show how species become modified, and to a certain extent how the theory of descent explains certain large classes of facts; and in these respects I received no assistance from my predecessors."

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