On Darwin's 200th Anniversary
— Ansar Fayyazuddin
THE YEAR 2009 is the 200th anniversary of the birth of Charles Darwin, as well as the 150th anniversary of the publication of his celebrated book On The Origin of Species by Means of Natural Selection. Darwin left an indelible mark on our understanding of the world we live in and our place in history.
Darwin is the subject of vast amounts of scholarly research, including much writing appearing in this anniversary year. Here I want to touch on a few aspects of Darwin’s life and work that I find interesting.
Darwin was born in 1809 into a wealthy family headed by his medical doctor father and his mother, the daughter of Josiah Wedgewood — the industrialist who made his fortune manufacturing fine china. Darwin’s mother died while he was still quite young. Charles’ father Robert, and grandfather Erasmus, were freethinkers, who rejected Christianity and, in the case of Erasmus, openly sought a materialist understanding of the natural world.
Indeed, Darwin’s grandfather believed in the interconnectedness and common origin of all species. In fact, the idea that species were related was an idea with some currency even before Charles Darwin made his contributions to the subject. The Linnaean taxonomy of the living world, in which the similarities of different living forms were used to classify them hierarchically as belonging to different kingdoms, phyla, classes, orders, families, genera and species was already in place.
The taxonomy posed — in retrospect at least — the question: if each species was created separately, as a literal reading of the Bible would imply, why were there structural similarities across species, genera, classes etc? Why was Linnaeus’ classification sensible?
While the interconnectedness and common origin of species, as a general idea, predates Darwin’s work by many years, what was lacking was a compelling mechanism for affecting the transformation of one species into another. Lamarckism was the one exception — it provided a way in which incremental changes could accumulate to give rise to the bigger differences that separated one species from another.
Lamarckism was based on the idea that physical changes accrued over the lifetime of an organism can be inherited by offspring. While I cannot dwell on this subject, I want to note that Darwin did not reject out of hand Lamarckian mechanisms in evolution, even in his later writings. (The genetic mechanism for evolutionary change wasn’t understood till much later.)
Careful Study, Brilliant Insight
Darwin presented a mechanism for accumulating incremental change based on a series of brilliant extrapolations from his own detailed factual knowledge of the natural world. Darwin’s reliance on knowledge acquired through careful study of nature distinguished him from the majority of his contemporary theorists of evolution, whose motivations were at times more ideological than scientific.
Darwin acquired this knowledge first as a boy and a young man avidly collecting beetles, an interest he shared with a burgeoning population of young naturalists who collected, sorted and displayed with pride the myriad varieties they had collected in the British outdoors. He went on to develop his knowledge of the natural world at Edinburgh and Cambridge.
At the end of his undergraduate years at Cambridge, Darwin had the great fortune of spending five years aboard the Beagle as a naturalist sailing all along the South American coast and further to the Galapagos Islands and Australia. Samples of animal and vegetable species, which he diligently collected and shipped back to England, ensured that on his return he was already a celebrated naturalist.
Later, in developing his theoretical ideas, Darwin undertook serious experimental work at home, breeding pigeons, conducting experiments on plants and, perhaps most importantly, enlisting the help of farmers and domestic animal breeders to learn about a subject that provided him the key metaphor for his work on the origin of species.
Darwin’s insight was based on a brilliant leap. He observed that within domesticated species there exist varieties. Dogs come in many varieties, commonly known as breeds, as do pigeons, cows and other domesticated species. Darwin connected the existence of varieties to the existence of species where in the latter, the differences are significantly greater than in the former. He made the point explicitly in the Origin:
“...varieties are species in the process of formation, or are, as I have called them incipient species.”
He went on to develop a parallel with the creation of varieties through selective breeding to the emergence of new species in nature. Selective breeding allows one to create specific varieties that would normally not exist if domestic animals were allowed to mate freely. If an analogous mechanism existed in nature to enhance particular qualities in the offspring through selective breeding, then that would explain the development of specific varieties at first that could then eventually develop enough to be called separate species. The differences further up the Linnaean hierarchy would simply be the extrapolation of this mechanism to create large enough differences.
The mechanism of selection that Darwin called “Natural Selection” was based on the differential ability of organisms to survive environmentally imposed constraints. These constraints could restrict the pool of a particular species to only those of its members with an enhanced ability to survive them. Breeding within the restricted pool, combined with random variation in the offspring, would then develop the variations that conferred advantages with respect to the environmental constraints.
Two competing yet complementary ideas informed the mechanism of selection — on the one hand, the heritability of traits; on the other, the random variation of traits in the offspring.
These necessary elements of Darwin’s mechanism verge on contradicting each other. The stability of species is based on offspring inheriting traits from their parents. Yet if offspring only inherited their parents’ traits, the transition from one species to another would not be possible. Thus random variations in traits must exist. These random variations would not accumulate in the absence of particular selective environmental pressures.
England in the first half of the 19th century was locked in a three-way struggle for class supremacy. The landed aristocracy with its increasingly precarious position in English society, the rising industrial bourgeoisie gathering economic and political strength, and the working class emerging with its first stirrings of class consciousness, fought for their interests in that particularly charged historical moment.
The Social Context
The overturning of the protectionist corn laws, in place to help the aristocracy against the capitalist market, and the brutal defeat of the workers’ Chartist movement,were significant moments marking the eventual victory of the English bourgeoisie. In front of everyone’s eyes, England was being transformed from an agrarian to an industrial society. History was not a cycle of birth and death but of change, and not random change but with a direction.
This is the world in which Charles Lyell, the geologist, and Darwin lived. Britain at that historical moment provided the metaphors of change, struggle and competition that informed that generation. The ideas of Thomas Malthus on natural constraints on humanity due to the incommensurate rates at which populations and the food supply increase, were popular and exerted a decisive influence on Darwin.
Lyell showed that mountains, oceans and all elements of the geological world are not static but changing. Small changes accumulate to transform one geological formation into another. And most importantly, that there is a history with a chronology that can be determined from observations today.
Darwin did the same for the living world. With the help of Lyell’s geology, he was able to propose the existence of a chronology of animal and plant life that could be recovered from fossils and the geological record.
Before Lyell and Darwin, the fixed laws of the physical sciences were their defining feature. When you perform an experiment in classical physics or chemistry, the outcome is independent of the starting time: that is, time is only relevant within the confines of a particular experiment and can be reset at will.
Darwin posed a serious challenge to this way of thinking about scientific knowledge. Two historical moments in natural history are not equivalent and the evolution's outcome cannot be predetermined. After all, natural selection relies on random variation and the particular “solution” to nature’s constraints is impossible to predict.
In addition, unlike physics and chemistry, where changing a few parameters are enough to adapt one situation to another similar one, the details of a given evolutionary natural history are central aspects of it, much like in ordinary history. The details and their causal relationships are the content of the scientific theory itself. Darwinian reasoning thus significantly expanded the scope of scientific inquiry.
The Origin and Today
The Origin of Species is a remarkable book. Unlike most classic works of science, Newton’s Principia for example, The Origin is relatively straightforward to comprehend. Even in relation to modern introductions to evolutionary theory, Darwin’s book stands out in its commitment to being understood. Darwin wrote no parallel book for the experts. The Origin was meant to serve both audiences. If there is a democratic purpose to science, if it is to make the world intelligible to ordinary people, then The Origin shows how one might achieve that purpose.
The democratic spirit evidenced in the stylistic simplicity of The Origin is also a central aspect of the content of Darwin’s theory. Evolutionary theory is not a “theory of progress.” A set of species that evolved later in time, for example, are not “superior” in any meaningful sense to their predecessors. Most evolutionary transformations are spurred by specific environmental challenges that do not change the level of complexity of the species or confer some absolute ahistorical and a-contextual advantage.
Nevertheless, both in popular depictions of evolution and in pseudoscientific racist theories, humans, and more specifically Northern Europeans, are often viewed as the endpoints of a linearly progressing evolutionary trajectory. Nothing could have been further from Darwin’s intent.
Darwin, at times at his peril, spoke out against rational justification of societal inequalities, particularly in the form of slavery, which he found completely abhorrent. Yet “scientific” metrics of ordering humanity into hierarchical schemes are constantly invented to give biological justification to the inequalities of society. These theories of race, gender, and class are based on a twisted sensibility that quite unjustifiably claim evolutionary theory as their basis.
Darin's influence permeates a far wider sphere than natural history itself. Although Darwin was not particularly mathematically inclined, central elements of his theory — variation and heritability — led to the first introduction of statistical thinking in the sciences and its rigorous foundation in mathematics. Statistical thinking is a mainstay not only of science, but of the way we often conceive problems of everyday life.
Nevertheless there are contested territories of the Darwinian legacy that often reflect the ideological commitments of the debate participants. These include the relative importance of natural selection and adaptation to other mechanisms of evolutionary change (random drift in populations, for instance), as well as the importance of non-genetic mechanism of inheritance.
Humans are not simply biological organisms; we live in societies that change our relationship to environmental pressures. Short-sighted people today, thanks to the social production of eyeglasses, are not subject to the unmediated consequences of their would-be handicap. More generally, culturally inherited knowledge impacts our ability to survive.
Darwin continues to excite debate, both among those who embrace his ideas and those who reject them. These debates are after all about what it means to be human and about our future.
I highly recommend reading The Origin of Species. While easy to understand, it may require a bit of persistence to wade through some of the more detailed explanations. But these details are of interest in their own right — a testament to the 20 years of thought that Darwin put into fleshing out his initial insight, and refuting his own doubts as well as those of his closest confidants.
Darwin’s Autobiography, written originally to provide a sketch of his life for his grandchildren, is a slender and very readable volume. In addition to an outline of his life, the book provides portraits of some major contemporary figures in British intellectual life, an account of Darwin’s loss of religious faith, his thoughts on the nature and acquisition of scientific knowledge, among other observations, making it an altogether delightful read.
Darwin: The Life of a Tormented Evolutionist by Adrian Desmond and James Moore (W.W. Norton and Company, 1994) is a tour-de-force biography putting Darwin’s life in the context of the larger unfolding of British history in that transformational political and intellectual period.
On evolutionary theory, I am fond of the treatment of evolution and creationism presented in Niles Eldredge’s book The Triumph of Evolution: and the failure of creationism (W.H. Freeman and Company, 2000), which is not only an excellent introduction to evolutionary theory, but is also a damning substantive debunking of “creation science” in its many guises.
ATC 143, November-December 2009