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Ghost Stories for Darwin
The Science of Variation and the Politics of Diversity
By Banu Subramaniam UNIVERSITY OF ILLINOIS PRESS
Copyright © 2014 Board of Trustees of the University of Illinois
All rights reserved.
ISBN: 978-0-252-09659-4
CHAPTER 1
Thigmatropic Tales
On the Politics and Social Lives of Morning Glories
weeds without value humorous beautiful weeds. —mary oliver, Morning Glory
a morning glory at my window satisfies me more than the metaphysics of books. —walt whitman, Leaves of Grass
An academy with separate and distinct disciplines has carved knowledge production into unique objects of studies and methodologies, obscuring the teeming life between the worlds of natures and cultures. A central goal of this book is to illustrate what an interdisciplinary naturecultural analysis would look like. In this chapter, I revisit my doctoral work on the maintenance of flower color variation in morning glories to explore how a feminist analysis can help explain the shape and scope of my research. How did it come to take the particular shape and form that it did? Might a naturecultural approach to flower color variation be different? Indeed, one of my claims here is that an interdisciplinary education would have fundamentally reshaped my work on the evolutionary biology of morning glory flower color variation. Inspired by the touch-sensitive thigmatropic tendrils of morning glories, which allow the plants to scale large objects and burrow into narrow crevices, I narrate tales of morning glories through the curious and adventurous tendrils of naturecultural storytelling.
Many a North Carolina Summer Morning ...
During fieldwork, I most remember the spectacular sight of morning glories on a warm summer morning. Splashes of purple, white, blues, and pinks in intense, dark, and light hues, all entangled. The flowers were fresh, open, shimmering in the morning dew. The bees and insects buzzed around them. By noon, the flowers withered under the blistering sun. Perhaps the bees had done their magic or perhaps the plants had fertilized themselves. By afternoon there was virtually no color in the field. By evening it was entirely a field of green. The following morning, another glorious vision. Despite the intense heat of southern summers, and even after years of backbreaking and sometimes futile fieldwork, the morning vision of morning glories always could stop my heart. They do indeed make the morning quite glorious!
Fifteen years later, I look at the same field of morning glories and see the ghostly apparitions of a eugenic past—the many mutilated, tortured, imperiled, and dead bodies, the stigmatized bodies of communities and nations of color, the poor, those deemed mentally incompetent, inferior, the many lives deemed not worth living. I see the methods, theories, and statistical models developed in the aid of eugenic goals, and the patriarchs who helped shape the discipline of evolutionary biology and hence my own disciplining and enculturation in the world of science: Darwin, Galton, Malthus, Pearson, Fisher, Dobzhansky, Haldane, Muller. Most had strong connections to ideas we now recognize as eugenic, connections that have been slowly forgotten or judged to be irrelevant. In tracing the genealogy of variation as an idea in the history of evolutionary biology, all these histories came tumbling out, the ghosts appearing in all their historical fineries. And feminists peeked out here and there in this history, intertwined in social policies that had complex and surprising twists and turns. This, then, is a story of how I came to examine the history of evolutionary biology, my horror and wonder at what my biological education had revealed and concealed, and my growing maturation into the complexities and contradictions of history and its implications for experimental practice.
Learning to see ghosts (and now haunted by my increasing inability not to see them) was itself an intellectual education. It meant understanding why I saw what I saw and why, after fifteen years of a different kind of education, I have come to see the morning glory fields so differently. I see these ghosts—of feminism, science, and politics—as revelations of what disciplinary structures conceal. Interdisciplinary work reveals what disciplinary histories have rendered invisible. Many years later, after meandering through the richness of intellectual pathways in the academy, I realize that disciplinary work—epistemology and ontology—is learned behavior.
An evolutionary biology of flower color variation allows us to ask questions about flowers in a field. It ignores how we came to see the field and the question of flower color variation as the obvious question. In evolutionary biology today, histories of race, gender, and sexuality are rendered invisible, indeed irrelevant to the question of flower color variation. Instead, as I began theorizing the field of morning glories and their variation as a graduate student, I began with the requisite scientific apparatus of clear hypotheses, making visible logical argument, good experimental design, appropriate statistical analyses, and careful interpretation of results. The ontology of flower recognition—the categories I came to recognize such as the color of the flower, its hues, its petal shape, and its reproductive anatomies and predilections—are things I learned to see as significant. Training to be an evolutionary biologist involved a "disciplining" to identify the "right" problems, learning to ask the "right" questions—being enculturated into seeing and observing in the particular ways of the field. The ontological categories such as flower color are "right" because they are seen as critical to evolution and the forces of natural selection. With this training, I came to look at a field of morning glories and wonder: Why all these flower colors? Why are they all not purple? What keeps the white flowers reproducing year after year, but always just around 10 to 15 percent? Why do you never see an entire field of white flowers? I cannot say that these questions were new. Many had asked them before, and I read their explorations with interest and these questions engaged me too.
Naturecultural Worlds
My work on morning glory flower color variation was grounded in the study of one of the most fundamental concepts in evolutionary biology—variation. In women's studies and ethnic studies, we pay a great deal of attention to the related concepts of diversity and difference. Did theories about plant diversity have anything to do with theories of human diversity? My training in evolutionary biology featured a history with scant attention to the humans that shaped the field; the focus was instead on the theories, experiments, models, and statistical techniques that were all in the service of purportedly explaining the nonhuman natural world. Inspired by feminist science studies and with a naturecultural view in mind, I began to explore the history of evolutionary biology and morning glories. This approach sparked a new set of questions: Why and how does one come to study a research object such as morning glories in a field of evolutionary biology, where human histories are largely deemed irrelevant? What if we consider such histories relevant? What can they teach us? Revising morning glory flower color variation as a naturecultural problem, I quickly discovered that the idea of variation in evolutionary biology has been intricately linked throughout history with ideas of human diversity and difference. In this chapter I revisit my doctoral research experiments testing evolutionary theories of flower color variation. In tandem with rethinking the experiments, I began to explore the biographies of "famous founders" in the field of evolutionary biology, becoming familiar with the historical debates in which modern theories on variation emerged. In the following chapter, I expand this analysis to trace the genealogy of the idea of variation through the history of evolutionary biology. In tracing this history, we will see that it takes researchers considerable work to understand the materiality of variation (as factors, genes, alleles, and DNA sequences), and that the history of the idea of variation is one that fundamentally travels from the worlds of nature (plants, animals, human biology, and subsequently molecular worlds) to the worlds of culture (ideas of diversity, difference, and inequality) and then back to the worlds of nature and then culture in endless loops. Indeed, the idea of the naturecultural would suggest that these are artificial distinctions and each is constitutive of the others. But telling this history necessitates that we hold on to the binaries of the natural and cultural worlds; I demonstrate how I came to discover these binaries and then unlearn them in a fragmented and disciplined academy. As I delved deeper into the historiography of eugenics, I discovered multiple histories. Internalist histories, largely told within evolutionary biology, ignore the political motivations of scientists or the social impact. Critical histories focus less on the science and more on the motivations of scientists and the social impact. Reading these contrasting histories, I came to again experience the ghostly presence of eugenics within the sanitized narratives of the disciplines.
The Genetics of morning Glory flower Color
Morning glory, Ipomoea purpurea, is an annual summer vine that grows about 2 m in length. It belongs to the family Convolvulaceae. It has heart-shaped, alternating leaves and, as its name suggests, its most distinctive feature are its flowers. Shaped like a funnel, the flower consists of five fused petals. The flowers are primarily pollinated by insects, especially bumble bees (Defelice 2001), but they are self-compatible and so can pollinate themselves.
A little digression here about morning glory flower color. How scientists go about understanding flower color variation brings us to the question of epistemology (or how we go about "knowing" what we know) in evolutionary biology. For contemporary evolutionary biology, the critical answers to flower color variation lie in following the genetics of morning glory flower color variation because evolution selects a phenotype (outward appearance) of flower color and its corresponding genotype (particular variants of genes or alleles). In insect-pollinated species such as morning glories, the visual cues of the flower are critical. So, to understand the patterns of phenotypes of flower color that are visible in the field, we need to understand the underlying genotypic variation to the phenotypes. Understanding how natural selection works at each of the individual flower color loci will help us see how natural selection maintains the variation of flower color that we can observe. If one is interested in evolution, flower color variation is an ideal model system in which to explore the actions of evolution (Clegg and Durbin 2000).
The genetics of flower color, it turns out, is not so simple. There appear to be multiple loci (the region of a chromosome that holds genes for a particular character is called a locus; plural loci) that determine the final color of a flower. Furthermore, at each locus, most populations have multiple variants of the gene (called alleles) circulating, creating floral polymorphisms. At least four main loci are believed to determine flower color variation.
• The p locus determines whether a flower is purple or pink. There are two main alleles at this locus: P and p (blue is "dominant" over pink). Therefore PP yields blue flowers, Pp yields blue flowers, and the recessive pp yields pink flowers.
• The w locus determines the intensity of the pigmentation and here the two alleles, W and w, are co-dominant—WW (dark color), Ww (light color), ww (white color). The white-colored flowers have rays of blue or pink depending on the alleles at the P locus.
Two other loci work very differently:
• The i locus works epistatically with (i.e., in concert with) the W locus to create a brilliant blue or pink. If a plant is ii and WW, then the flower will show intense blue or pink pigmentation with a velvety sheen.
• The a locus works epistatically on all other loci. If a plant is a recessive homozygote, aa, then it works epistatically to shut off all the other loci, so the flower is albino—pure white with no rays at all.
Contemporary evolutionary biology, like much of the biological sciences, is a reductionist science by design—grounded in the belief that breaking down a complex phenomenon into its individual parts and understanding each of the parts will yield a complete understanding of the whole. Understanding the world of natural selection at each locus, this approach argues, helps us understand what is happening to the whole flower and its color. Evolutionary biology foregrounds narratives where the visible traits we see—phenotype or frequencies—are the product of the complex workings of natural selection at the genotypes of the different loci that determine that particular trait. Therefore, to understand the splashes of color in an open field, one needs to understand how natural selection is working on these various attributes of color—color of the flower, its hue, iridescence, and so on. Most likely, the stories at each of the four loci—p, w, i, a—are different. A good experiment would be designed to understand the workings of natural selection at each locus separately. For the purposes of this chapter I focus on the w locus.
THE EXPERIMENTS
Here, I discuss two experiments that animate this work (Subramaniam 1994). Both deal with the w locus. The first focuses on the frequency of the two alleles W and w and the second on the fitness or relative performance of the three genotypes at the W locus—WW, Ww, and ww.
Frequency of W/w
The w locus determines the intensity of flower pigmentation. Two alleles circulate in most populations, W and w, and they are co-dominant, producing dark-colored flowers with darker rays (WW), light-colored flowers with dark rays (Ww), and white flowers with dark rays (ww). The color of the flower (and rays) depends on the alleles on the p locus. W and w are said to be codominant since both alleles express themselves in the heterozygous state (Ww). Surveys of fields show that w ranges in frequency from zero to 15 percent and it is almost never higher than 15 percent. Why not? What limits the w from increasing in frequency and what forces work to keep w as an extant allele—why is it not eliminated? Why do we not have W as the only allele in morning glory populations?
I began with four field sites. All the experimental sites were selected so that there were no morning glory fields in the immediate vicinity. This was to ensure that no pollen (or only miniscule amounts) from other the experimental plants would affect the experiment. Two experimental treatments were created. Two of the fields were planted with high frequencies of the W allele and the other two with high frequencies of the w allele. The seeds for the experiments were generated through an elaborate series of genetic crosses so that all individuals—WW, Ww, ww—came from a similar genetic background. Therefore, any differences we saw could be attributed to the w locus. Plants on the four field sites were allowed to grow, flower, and go to seed over the growing season until the frost killed the plants. All the seeds were collected, and then the frequency of the two alleles W and w in the next generation (i.e., the seeds) were ascertained by growing them in the greenhouse. And then the moment of suspense: seeing whether the fields would increase, decrease, or maintain their initial frequencies of alleles. And the results were exciting!
(Continues...)
Excerpted from Ghost Stories for Darwin by Banu Subramaniam. Copyright © 2014 Board of Trustees of the University of Illinois. Excerpted by permission of UNIVERSITY OF ILLINOIS PRESS.
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