Check out my review of Peter Bowler’s 2013 book, Darwin Deleted: Imagining a World Without Darwin, at BooksandIdeas.net!
Book review: Darwin Deleted
January 13th, 2014
By Rachel Mason Dentinger
The Sons of Scientists
December 18th, 2013
By Rachel Mason Dentinger
I once interviewed a prominent ecologist for my doctoral research, whose partner told me, “You know, these [prominent ecologists], they all have really strong mothers, influential women that encouraged them to explore nature.” I liked this theory, though I didn’t have much proof to support it, so I thought better of mentioning it in my dissertation.
I bring this story up today only because I want to completely disavow any sort of similar claim that you may or may not imagine I am making with my title. In fact, once I realized that this was the post that I was writing, I was slightly embarrassed. You see, by pure chance, I have researched the work of a lot of scientists with sons.
The first was Carroll Williams, an insect physiologist whose work I ran across early in my doctoral career. In leading his lab at Harvard in the 1950s, he solved a small scientific mystery, a sort of biochemical whodunit. Whole generations of his insect subjects were mysteriously dying. They grew and grew, but never developed into mature adults, remaining outsized juveniles, unable to reproduce.
His sleuthing led him finally to the paper towels he used to line their petri-dish homes. But when he wrote to the manufacturer to ask for the makeup of the towels, the answer he received was simply this: “paper pulp.” Not one to be disheartened, Williams hypothesized that the trees used to make the pulp must produce chemicals that acted as hormone mimics, disrupting the development of his insect subjects—compounds that had likely evolved in response to insect feeding, as a form of “natural insecticide.” He even managed to isolate this substance and verify that it was responsible for the death of his experimental insects.
Williams’ fascination with “natural insecticides” was shared by the coevolutionary theorists at the core of my Ph.D. research, so when I learned that the Harvard University Archives held his collected papers, I was pretty excited to get a look at them. Typically, I seek out a scientist’s children when it proves impossible to locate the scientist’s papers in any archive, in the hopes that their family has stashed away boxes of letters and research notebooks in a nice dry attic somewhere. But in this case, while Williams’ papers were already conveniently deposited in an archive, I needed special familial permission to gain access to them. Luckily, I had the internet to help with own my sleuthing, and I tracked down one of Williams’ sons, Roger, who kindly sent Harvard notice that I could see his father’s papers.
Another scientist whose son I have contacted is Gottfried S. Fraenkel—again, an insect physiologist and a near contemporary of Williams. Fraenkel was far more interested in insect nutrition than in hormones, however. In fact, it was his interest in nutrition that brought me into contact with his son, Gideon, who has had a career as an organic chemist himself. I was revising a paper about Fraenkel the senior, starting with his work in the UK in the ‘30s and ‘40s on the molecules of nutrition. Later Fraenkel moved to the US, where he began to hypothesize about the evolution of insect feeding choices. But in 1946, a couple of years before he left the UK, Fraenkel contributed to a Fabian Society tract on agriculture, arguing vehemently against the capitalist conspiracy to foist white bread on an unsuspecting public. Using his favorite research subject, the confused flour beetle, Fraenkel had demonstrated that refined grain was nutritionally deficient. Even more significantly, he found that refortifying the bread with the nutrients removed in processing still produced a nutritionally inferior product—a very nice story in light of growing scientific consensus that vitamin supplementation may be fairly worthless (or worse!).
In other words, Fraenkel suggested—back in the 1940s—a fairly holistic concept which has seemed increasingly convincing in recent years: nutrients are healthful in the context of food, but a disembodied molecule (even when added back in to food) is of dubious value. The reductionist reliance on nutrients has not attracted a ton of media attention, though Michael Pollan wrote a nice piece on this topic some years ago (and I loved the molecular banana cover image for this piece!). Expect more coverage now, however; just today, NPR has rounded up recent research on the value of vitamins, which is well worth checking out.
But back to the sons of scientists! When I first wrote the paper on Fraenkel, I did not realize that he was instrumental in naming brown bread the National Loaf of Great Britain. In other words, there was a UK-government mandated insistence on whole wheat as early as the 1940s! (Yet, my kid’s nursery today serves white toast to preschoolers who otherwise would not even know that such an abomination exists…) And I only learned about this thanks to Gideon Fraenkel, who actually wrote a letter to the New York Times on the subject.
One son of an scientist, I am chagrined to admit, may have been unhappy with how I portrayed his father. Warm and welcoming when I was viewing his father’s correspondence, I never heard from him again after sending him a draft of the paper that examined some of his father’s work. This is certainly the biggest danger in interacting directly with a subject’s children; they naturally want to see their parent’s work only celebrated.
Most recently, when I traveled to Boston for the 2013 History of Science Society meeting, I was lucky enough to meet with the son of one of my current subjects. Don Eyles was a parasitologist working for the NIH in 1960 when he was accidentally infected with a malaria parasite that had been isolated from a Malaysian (or, rather, Malayan, at the time) macaque. Though the infection of humans with monkey malaria had, in truth, been known for decades, malariologists regarded the possibility as so remote that used little caution with the monkey malarias, even when working with heavily infected mosquitoes. Eyles was one of the first to learn that this was a mistake: What seemed like a meaningless mosquito bite while running an experiment became, for him, a case of malaria. And thus ensued three years of intensive NIH-funded lab and field research on a variety of monkey malarias and their mosquito vectors.
Admittedly, when I started searching for the children of Don Eyles, I immediately saw that his son—his namesake, in fact—lives in Boston. Eyles Jr. is an interesting person in his own right, having worked as programmer on the moon mission. The BBC referred to him as a “Beatnik” who put men on the moon. And here Eyles has written a paper about technical problems on the mission.
Meeting with him last month, I enjoyed my requisite Bostonian lobster lunch and gratefully received the gift of historical treasures from him. He lent me a very cool 1966 New York Times Magazine with a cover article on his father’s malaria research project. And he gave me a copy of the memoir of his fascinating mother, Mary Stipe Eyles, who was herself trained as a scientist and taught high school biology for many years. His mother and his two younger siblings were with Don Eyles Sr. when he tragically died of a heart attack in 1963, just as the family was about to return to the US from Malaysia.
Don Eyles Jr. (who even, by the way, attended my talk at the conference!) promises to put me in touch with his sister, one of the above-mentioned younger siblings, who lived in Malaysia with her family while her father pursued local monkey malarias. Check out photos of the family here.
I may finally have my chance to talk to the daughter of a scientist! And I have no doubt that she will be just as helpful and insightful as the very kind scientists’ sons who have kindly assisted me in the past!
Making the scientist, making the place for science
March 28th, 2012
By Rachel Mason Dentinger
Kew’s exhibition, “Joseph Dalton Hooker: Botanical Trailblazer,” highlights handsome illustrations and provides a personal and professional cross-section of the making of a Victorian scientific career. But tantalizing morsels hint at tensions between public needs and professional goals in the life of a scientist and in the operations of a scientific institution like Kew, leaving the visitor wanting more.
“Kew is what my father and I have made it by our sole unaided efforts,” claimed Joseph Dalton Hooker in the early 1870s, affronted by a Board of Works proposal to eviscerate the scientific function of Kew Gardens. The proposal to transfer Kew’s herbarium collections of dried plants to a new museum soon to be opened in South Kensington (now known as the Natural History Museum) was politically framed as an attempt to streamline government-funded institutions and reduce spending. But Hooker saw it instead as a direct attack on his scientific career.
He had strived for decades to support himself through botanical work, making expeditions to the ends of the earth to collect new species of plants for Kew Gardens. Finally, in 1855, his father, Sir William Jackson Hooker, the first director of Kew, was able to hire him as assistant director. And in 1865, with his father’s death, J.D. Hooker became director himself. But now, just when he had ascended to the rank that would allow him to shape botany into a properly scientific pursuit, this proposal threatened to turn Kew into a mere pleasure garden, and to turn Hooker himself into a mere public servant.
Of course, ever since Kew was made public in 1841, its director was expected to act, to some extent, as a public servant, assisting horticulturalist and farmers at home and abroad with various botanical conundrums. Hooker himself became known for his aid in transplanting useful plants to colonial outposts: bringing quinine and rubber from South America to India, and disease-resistant coffee from West Africa to Sri Lanka. But Hooker believed just as strongly that Kew must serve the needs of botanical science, and to that end the herbarium was essential.
Fortunately, the safety of Kew’s herbarium was secured by 1874, thanks especially to the exertions of that infamous firebrand evolutionist Thomas H. Huxley. But questions about the Gardens’ function remained. In fact, while this exhibit largely glosses over the near-catastrophe of the early 1870s, comical illustration from later in the decade arrest the visitor’s attention, depicting Kew Gardens as a place where the enjoyment of the public and the work of scientists directly conflicted. In 1883, the Gardens began opening at noon; but prior to this shift, an opening time of 1pm prolonged the morning hours that scientists and students could work in Kew, undisturbed by the baser concerns of the general public. This one extra hour of public access was the hard-won product of at least seven years of public protest, if we are to judge by the date on a large cartoon: Inside the Gardens’ walls the privileged few luxuriate while the rabble pickets outside with signs like “Down with the select arrangement. No peace until satisfied” and “Give the public justice.” This cartoon, as with other such images in the exhibit, is inexplicably unreferenced, which is a shame, since visitors could better understand the illustrations’ significance with knowledge of their sources.
But Hooker’s place as the gatekeeper of Kew’s scientific reputation was also hard-won and it’s easy to understand his staunch defense of the Gardens as, first and foremost, a place for science. Both his and his father’s early careers had not been easy, and in building the scientific reputation of Kew, he built himself into a scientist in parallel. His trips around the world had fed the growing herbarium; according to the exhibit, over his 70-year career, Hooker identified more than 12,000 new plant species. Hooker sketched many of his collections while he was in the field. It’s wonderful to see the handwritten evidence of fieldwork found in researchers’ field notebooks, and Hooker’s sketches of plants and landscapes are some of the most engaging illustrations in the exhibit, drawing the visitor in to Hooker’s travels.
Using these collections, Hooker also asked larger questions about plants. In 1839, when he was only 22, he set off on his first long voyage, working as the assistant surgeon on an Antarctic expedition (though he preferred, according to the exhibit, his unofficial title of ‘Botanist to the Expedition’). Observing patterns of similarity and difference between plants found on the continents he visited gave him a lifelong fascination with the geographical distribution of plant species.
In highlighting Hooker’s astute observations of the geographical distribution of plants, the exhibit also presents a rather funny incongruity. Hooker is credited in one breath with cultivating non-native plants like quinine and coffee in the colonial landscape, and in the next with a prescient understanding of the ecological dangers of non-native species. In particular, we are told that upon visiting various islands in his travels around the Antarctic, Hooker became aware that non-native species were damaging to their “unique plant communities. These problems continue today with invasive non-native plant species overwhelming natural habitats, pushing some native species to the brink of extinction.” The irony of this is only heightened by Hooker’s renown for bringing the seeds of unfamiliar varieties of rhododendron back from the Himalayas. As popular plants in the Gardens, some of these may still be seen today in Kew’s Rhododendron Dell—as well as outside the garden where some “escapees” have come to act “invasively,” and are considered a non-native nuisance.
This apparent contradiction is no mistake—in fact, it reflects a cognitive dissonance that still thrives in biology, where organisms may sometimes be cast as emigrants and other times as invaders, where one moment one is a great success in a new ecological niche and the next a weedy marauder. The identity that a newly introduced species assumes rests to a large extent on cultural context rather than biological fact—which supports no opinion either way.
To be fair, though, J.D. Hooker’s scientific legacy is felt more in evolutionary biology than in invasion ecology. Hooker began his 40-year friendship with Charles Darwin just as he was setting off on his Antarctic expedition in 1839. And by the time Hooker left for the Himalayas in 1847, Darwin had confided in him his developing theory of natural selection. Thus, on this adventure, Hooker travelled, as a video in the exhibit says, with “a shopping list for Charles Darwin,” acting as Darwin’s eyes and ears in the field. “I congratulate myself in a most unfair advantage of you,” Darwin wrote to Hooker, “viz in having extracted more fact and views from you than any other person.” Considering what it must have meant for Hooker to have the seed of Darwin’s theory already planted in his mind a dozen years before the publication of On the Origin of Species, for him to see the vegetation of the Himalayas through that lens, it’s easy to understand how Hooker’s assistance and—later—his support of natural selection became indispensable to Darwin.
“Joseph Dalton Hooker: Botanical Trailblazer” does a good job of touching on many of the major themes in Hooker’s life and work and it is a worth a visit. But you must hurry to the Shirley Sherwood Gallery of Botanical Art, for the exhibit closes on Monday 9th April. If you wait till after 31st March, you will also be lucky enough to catch Rachel Pedder-Smith’s awesome herbarium specimen paintings.
For Further Information:
The exhibit has a very nice little companion volume, which can be purchased at the Kew gift shop, and features a great introduction by historian of science Jim Endersby. I admit that I have not read his book Imperial nature: Joseph Hooker and the practices of Victorian science, but it looks like within its pages you can find out more about the near-demise of the Kew Herbarium in the early 1870s, a controversy that was named the “Ayrton Affair” after the head of the Board of Works, Acton Smee Ayrton. (The Ayrton Affair was also just one element within the Royal Commission on Scientific Instruction, also known as the Devonshire Commission.)
For more on the history of the Royal Botanic Gardens, Kew, check out their cool historical timeline.
If you would like to learn more about why I put “invasive species” in scare quotes, read out my own article on the subject at The Naked Scientists and check out this 2011 Nature article, entitled “Don’t judge species on their origins,” which you can actually read for free here, thanks to the US Forest Service!
Darwin’s finches – and Darwin’s humans
August 16th, 2011
By Rachel Mason Dentinger
Darwin gets a lot of credit in biology. And rightly so, given the sheer quantity of persuasive proofs and fascinating conundrums that he put forth during his career. This is a man who saw a foot-long nectary on an orchid from Madagascar and asserted the existence, sight unseen, of a moth with a proboscis long enough to reach the nectar at the bottom and pollinate the flower. Forty years later he was proven correct. So it is no exaggeration to say that Darwin left a legacy of leads for his intellectual inheritors, many of whom are fond of claiming Darwin not only as an ancestor but also as the source of all of the best ideas and problems in evolutionary biology to this day.
The Galápagos Islands have long been the scene of such claims. Darwin travelled around the world from 1831 to 1836, but he spent barely over than a month exploring the Galápagos.
Even so, this volcanic archipelago off the coast of Ecuador became one of the iconic locations of Darwin’s Beagle voyage. Because of the attention that Darwin drew to the evolutionary dynamics of the Galápagos, the islands became a so-called “natural laboratory,” where biologists have gone for generations to watch evolution in action.
In this month’s issue of Evolution, researchers led by Fernando de León from McGill University in Montréal chose these iconic islands —and one of their most iconic groups of animals, the birds known as Darwin’s finches— as the arena for tackling an appropriately Darwinian question: How do humans alter the trajectory of other species’ evolution?
This question is at the heart of Darwinian theory itself. The very name that Darwin gave to his mechanism for evolutionary change reveals how difficult it is for humans to think about evolutionary change without becoming self-referential. Natural selection is actually a passive process in which nobody is directly or consciously selecting anything. The wing length or leaf shape or antennae placement that is “selected” is merely that which allows the animal or plant to face the challenges presented by its environment and have babies that can do the same. The term “natural selection” reflects the analogy that Darwin made between what happens in nature, the product of mere survival, and what happens when humans interfere with nature and breed specific features into animals and plants through artificial selection.
In other words, humans have long been altering the trajectory of other species’ evolution. But animal and plant breeding is only the most obvious and most intentional way that we do this. As animals ourselves, with our own needs and interests, we have also been unintentionally changing the course of evolution since we came into existence.
How do we evaluate the evolutionary effects that we have on other organisms? More to the point, must we evaluate them? All animals and plants irrevocably shape the evolution of others in ways both large and small. How many of these organisms waste time worrying whether these evolutionary impacts are good or bad? It’s probably safe to say that Homo sapiens are the only ones.
In the case of Darwin’s finches on the Galápagos Islands, our authors begin with the premise that the human effect on evolution is a bad one. They investigate the loss of diversity within a particular population of finches. Darwin’s finches are distinctive for their specialized beaks, whether they eat insects or nectar or cacti. Medium ground finches (Geospiza fortis), the focus of this study, eat seeds.
Following this particular species over the decades, researchers have observed that it appears to be diverging into two specialized “morphs,” two groups with different beak forms. Medium ground finches with larger beaks specialize on larger, harder seeds, and those with smaller beaks specialize on smaller, softer seeds.
But the population in Academy Bay on Santa Cruz Island looks different. Academy Bay is one of the more populous human communities in the Galápagos and, as a result, human foods have become more and more available to the finches. This wealth of new food has slowed down the evolutionary divergence-in-action, leading to the slow homogenization of beak sizes in the Academy Bay population.
As de León and his colleagues put it, human food is “eroding the diet-based disruptive selection that is thought to have previously maintained beak size modality in G. fortis.” Simply put, elsewhere in the Galápagos, the natural food sources of these birds seem to be driving the evolution of these finches into two distinct groups. But the presence of humans and their foods stifles this evolutionary process.
Why do we care about “eroding” the “disruptive selection” in the Galápagos—or anywhere, for that matter? One critical reason is that this type of selection maintains diversity. And diversity represents evolutionary potential. In a world that changes all of the time in unpredictable ways, diversity is the source of adaptation to change. Genetic diversity within populations is a natural resource, an evolutionary reserve; if climate change eliminates the food source that most individuals in a population rely upon, a few hardy survivors could still exploit some new and unanticipated food source. But that potential only exists when there is diversity within a population. It’s trite but true: diversity is the raw material of evolutionary adaptation.
The authors conclude that the case of the medium ground finch in Academy Bay is another example of “the importance of conserving the processes that generate and maintain biodiversity, rather than just the product of those processes.” The products, of course, are the organisms themselves. This approach to conservation has become increasingly common in recent years. Its proponents argue that we miss the point of conservation when we champion the cause of individual species and ignore the processes of biological change that generate the all-important, more valuable prize of diversity itself.
As arguments for conservation go, protecting an evolutionary process probably does not tug the heartstrings of most nature lovers. And as an intellectual argument, it’s important to note that evolution and evolutionary processes do not themselves have any intrinsic value. When we argue for the conservation of an evolutionary process, we must argue for it as an investment in the future, an investment in the generation of biological unpredictability in all of its incipient evolutionary potential.
But it’s difficult to know precisely how an evolutionary process may be conserved, and it’s a question that the authors do not address in this paper. In the case of Darwin’s finches, you might assume that the authors would advocate the restoration of the disruptive selection “eroded” by the availability of human foods. But they could hardly argue for the elimination of the human influences on finches in Academy Bay. After all, without humans, these biologists would have missed their chance to watch a new evolutionary story playing out. In other words, while the human community in Academy Bay could be taken as a threat to the Galápagos, we can also appreciate how it increases the archipelago’s utility as a “natural laboratory.”
Even Darwin’s finches could find some utility in their entanglement with humans. Without access to human foods, the medium ground finches of Academy Bay may have continued to diverge into two new species, each one specialized on its respective food source, thanks to its respective beak size. The multiplication of species is certainly a form of diversification. The irony, however, is that specialization does not necessarily lead to great adaptability in the future. In this sense, then, losing the close linkage between a specific food source and a specific beak morphology could be a boon for the medium ground finch, a generalizing force that might allow them to exploit a variety of foods in the unpredictable future that they face.
Should these last arguments for the utility of human influence make your inner conservationist cringe, consider that humans have always influenced —and been influenced by— the evolutionary trajectories of other species. It’s only recently that scientists have seen this form of evolutionary interaction as suitable for naturalistic investigation. And what more appropriate place to investigate the place of humans in evolutionary processes than in the iconically Darwinian Galápagos Islands?
When identical genes just aren’t enough
May 25th, 2011
By Rachel Mason Dentinger
For the last decade, everyone has been excited about the medical possibilities of stem cells.
Need a new liver? What if we could grow one for you in essentially the same way that you grew your first liver when you were in your mother’s womb?
That’s the promise of stem cells, that scientists could take an undifferentiated cell, just like the cells that made you up before you were even you, insert your own DNA into it, and direct it to differentiate into a new liver or kidney or heart. Even better, because the new liver has your own DNA, your body’s immune system will welcome it as one of its own. In a traditional transplant, your immune system must be suppressed, or it will recognize the new liver as an outsider and “reject” it (that’s a euphemism for killing the new organ).
One problem. Those embryonic cells, known as embryonic stem cells, come from only one place: embryos. This fact has made a lot of people uneasy or worse, especially because human embryonic stem cells are derived from aborted embryos. So you can imagine everyone’s excitement a few years ago, when scientists were able to take adult cells and turn them into stem cells. These are called induced pluripotent stem cells—“induced” because they didn’t start out as stem cells, and “pluripotent,” because they have the potential to become many (think “plural”) different types of cells.
This achievement eliminated the ethical problems of using aborted embryos. Even better, it could still produce cells that were genetically identical to the person receiving them, thereby avoiding that pesky immune system problem.
So scientists assumed. But sometimes identical genes just aren’t enough, as it turns out. Thus transpires another opportunity for us all to learn that genes aren’t everything!
“Epigenetic effects” are biological changes in cells that are outside or beyond (that’s “epi”) of the genes. Throughout my life, my genetic sequence remains the same in every cell of my body. Clearly, however, in different cells and at different ages, those genes are “expressed” differently, meaning that different proteins are produced from the same genes under different conditions. My poor old cells know that I am heading into my mid-30s, despite the fact that their DNA is identical to the DNA of the fresh young cells that I rocked in my 20s.
Sadly, some adult cells induced into becoming stem cells may not be able to forget their real age either. A group in San Diego just published a paper in Nature showing that some types of induced pluripotent stem cells overproduce certain proteins, which allow the immune systems of the animals (mice, in this case) receiving the implanted cells to recognize them as intruders and kill them.
There are other ways of inducing pluripotency, so it’s really not the end of this kind of research. But hopefully it’s the end of assuming that it’s enough to be genetically identical. It’s also one more reason to reconsider the use of embryonic stem cells. Even on the cellular level, youth is one thing you just can’t fake.
For further reading on this research, see the link to the Nature paper above and check out the New York Times coverage.
For further reading on how scientists became fixated on DNA as a “master molecule,” check out the work of some fantastic females from my field and enjoy Evelyn Fox Keller‘s The Century of the Gene and Lily Kay‘s Who Wrote the Book of Life? A History of the Genetic Code.
The Rilkean Imperative
March 18th, 2011
By Rachel Mason Dentinger
In the early years of the 20th century, a 19-year-old student began a correspondence with the Austrian poet Rainer Maria Rilke, seeking advice on his own poetic efforts. Rilke’s responses, compiled in one of my favorite books of all time, Letters to a Young Poet, seem at times to dissuade the aspiring poet. In his first letter, Rilke gave his correspondent a challenging litmus test to help him determine whether or not he should even attempt to live the writer’s life.
“[A]sk yourself in the most silent hour of your night: must I write? Dig into yourself for a deep answer. And if this answer rings out in assent, if you meet this solemn question with a strong, simple ‘I must,’ then build your life in accordance with this necessity.” But if there is no clear “I must,” Rilke told him, then there is no question: he must not.
I have always felt myself to be balanced unsteadily on the fulcrum of this Rilkean imperative. For Rilke, “I must” means literally: “I would have to die if I were forbidden to write.” That is one uncompromising position. And as much as I have always wanted to be a writer, so many days of my life I simply don’t write. By Rilke’s standards, I likely lack the urgency and perseverance to make my life and my livelihood as a writer. And now, more than ever before (thanks to a little person who takes up a large percentage of my thoughts, time, and heart), I lack the ability to “build my life” completely around writing. I’m pretty sure that I fail Rilke’s test.
But not writing is almost always more complicated than poor time management or a lack of perseverance. It’s caused not only by daily work, distractions, and lack of discipline, but also by the peculiarities of my own interior life. More specifically, my very real lack of discipline is only compounded and amplified by my lack of courage. Yes, I want to be a writer, but what if I can’t pull it off? What if I just don’t have what it takes?
And then there is the simple reality that even in the face of an internal “I must,” it’s still work, after all! In other words, in the “most silent hour” of my afternoon (that’s the scant 2-hours, if I am lucky, of the baby’s nap time), I ask myself: “must I write?” And then I see the dishes and laundry and hoovering that need to be done. More than anything, these other tasks are compellingly simple and satisfying. I know that I can succeed as a homemaker; I love to make tidy lists of discrete tasks and cross them off as I accomplish them. But as a writer, the tasks, the process, and the value of the final product are all a little too ambiguous. I’ve learned that the surest way to open up a yawning abyss of uncertainty and potential failure in the middle of an otherwise fulfilling “to-do” list is to make task number one “start writing.” That item always gets shunted to the foot of the list, if it’s included at all.
Which is not to say that it doesn’t feel natural and deeply right to be writing. In fact, that’s another component of the problem; I have never been able to teach myself how to take something that feels so natural and turn it into a daily discipline.
In any case, how much can a poet’s test tell someone who wants to write non-fiction pieces about science and the history of science? I’m not sure, since I have always struggled to understand how poetry fits in to the scientific or scholarly life. But I do think that most writing, of any form, is a process of building connections. Or else it is a process of observing the connections that already exist. If this last sounds almost mystical to you, then you’ll love what I am going to divulge next. For me, all writing seems just a tiny bit alchemical. I just don’t know how it happens. I don’t understand how images and experience and knowledge could possibly be transmuted, through the labor of composing sentences, into something more, something whole. And yet, they are.
Moreover, in my experience, sometimes writing is done best in the complete absence of writing. Writing is both a physical and mental labor, an intense effort to observe and build connections. But when I use writing to look intensely at an object, interesting new connections are almost certain to appear in my peripheral vision. And it’s not until I take a break from all of that intensity, step away from the computer or notebook, that I can begin see the whole picture. In the vacuum created by stepping away, there’s freedom, room to breathe and think more fluidly. Every time that I have spent a long time writing, I have felt a need to escape it. It could be just a momentary escape, walking to the window or getting a glass of water. Or it could be a break of a week or two. And it’s almost always the case that when I return, something new emerges or a confused idea becomes clear.
You can probably see now that my slippery and quasi-mystical ideas about writing might be getting in the way of turning myself into a disciplined writer.
But I have come close in the past. In fact, poetry was the medium that first brought me closest to daily disciplined writing. As an undergraduate biology major, I took poetry workshops where I was required to submit my work for discussion and critique by the group. The pressure of this public performance was enough to keep me writing more regularly than ever before.
More recently and more relevantly, I wrote my dissertation. I thought this latter would be a true test of my commitment to writing, a demonstration of my capacity for disciplined work and my ability to live the writer’s life. But just like the poetry workshops, there was always an audience waiting, readers with expectations, which helped fuel my discipline; hardly the “silent hour of your night” that Rilke requires.
And yes, I do think that the Rilkean silence and isolation of the night is important. Of course it’s true that writers always have audiences. But the longer I consider what it takes to become a writer, to live my life as a writer, the more convinced I become that a crucial element is the willingness and courage to plunge ahead without too much consciousness of the critical eye of the reader. The reader demands and I may well produce to meet that demand. But the free-market, supply-and-demand model of writing only takes me so far.
What if, instead, the demand for my writing originated within? What if the drive was self-contained, rather than based upon a desire to please an external judge? Granted, it doesn’t sound like the most lucrative approach to writing. But there’s nothing lucrative in not writing, either.
Perhaps this is just what it takes, to ask myself: Must I? To answer: I must!
A day in the life of a field mycologist.
March 10th, 2011
By Rachel Mason Dentinger
My husband is always pestering me, “Hey, you’re a historian of science—why don’t you study the history of mycology?” Or, “You want to write about science, right? The study of mushrooms is pretty cool, why don’t you write about mushrooms?”
Well, alright. After all, these elusive, mysterious fungal reproductive organs brought us here to Borneo, it seems only fair that I finally write something about them.
There you are, then, that’s something about mushrooms: A mushroom is the reproductive structure, also called the fruit body, of a fungus. Most fungi that you or I would recognize are, like plants, multicellular organisms with stiff outer cell walls—that’s the part that’s hard for our bodies to digest when we eat uncooked vegetables or mushrooms. Like all multicellular organisms, the work of living is divided up between different cells. Most of the “body” of a fungus exists where we cannot see it. That is the mycelium, a filamentous structure that grows underground or through a decaying log—wherever the fungus resides. It absorbs nutrients, exchanges gases, and expands the fungus’ territory; it’s in charge of all the stuff of daily life. But when a mushroom appears aboveground, it’s time for reproduction.
This is why mushrooms are so important to mycologists. Like a lot of other organisms on this planet, reproductive systems provide a lot of clues about the identity of an organism, how it’s related to other organisms, and its evolutionary history. One of the really wonderful (some would even say seductive) things about biology and evolutionary theory is its intuitive appeal, and this concept is no exception! If evolution is a matter of survival and reproduction over thousands of generations, then it makes a lot of sense that many biological questions and problems would revolve around understanding how cells and organisms produce the next generation. For example, if you have ever taken a course in botany, you know that basic plant identification begins with the reproductive organs, the flowers: the number of petals and the arrangement of the pistils and stamens, which are the flower’s sex organs, these are the keys to identifying flowering plants.
Another level of “identification” is the attempt to understand what a species is. This is a knotty issue, both philosophically and practically, but an inability to interbreed is used by many as a basic criterion for separate species. If two organisms cannot mix their genes to produce viable offspring, for whatever reason—it could be physical, behavioral, or genetic—they belong to two different species. You get the picture: sex is biologically important, thus biologists are often focused on reproductive organs.
In a practical, day-to-day sense, then, my husband spends a lot of time looking at fungal sex organs. And what does he see? In order to show you, I am going to take you for a walk in the muddy wellies of a field mycologist.
Here we are in Borneo, exploring a tropical rainforest. We are on the opposite side of the biological universe from the boreal forest of northern Minnesota, where my husband Bryn grew up. So how does Bryn know where to look for mushrooms? In a sense, the answer is: he looks everywhere. It’s true, and anyone who knows him will confirm it, he never stops looking! However, like any mycologist, my husband usually has some sense of where to head first…
As you walk through the rainforest, remember that mushrooms do not live in isolation. While much is made of the work that fungi do in decomposing dead forest debris (and certainly they are amongst the most important decomposers in the forest), a lot of fungi are not decomposers. Instead, many fungi live in symbiosis with plants, called a mycorrhizal association. To put this symbiosis in perspective: If all of the fungal partners in this marriage were to file for divorce tomorrow, almost all of the forested land in the temperate Northern Hemisphere would be treeless. Luckily, however, a complex exchange of nutrients and water makes this partnership sustaining and beneficial for both sides. Thus, the first thing Bryn looks for is a type of forest. Wherever we go, he has already learned as much as he can about the kind of trees we will find, and he knows which ones are most likely to have the kind of symbiosis with mushrooms that he is looking for. Here in Gunung Mulu National Park, we are seeking lowland tropical rainforest giants: the dipterocarps. This is a group of trees that are especially abundant and diverse in Asia—and especially here in Borneo.
Of course, because these trees are gargantuan, there’s an added difficulty: you can’t see the leaves, they are too high up! And many of the leaves in the tropical forest look very similar, so they are difficult to identify anyway. As Bryn has said, to be a mycologist in the tropics, you practically have to be a botanist as well—and, indeed, he spends a lot of time trying to identify trees and detect patterns of association between trees and mushrooms.
For your purposes, though, just start by looking for some very big tree buttresses, those huge wedge-shaped roots that tropical trees use to prop themselves up because they are so shallowly rooted. Yep, that means you have to go off the trail, so watch out for pit vipers and toxic, furry urticating caterpillars! Poke around in the crevices between these buttresses and you’re bound to turn up something.
Some mushrooms can be identified morphologically, that is, by examining their appearance, whether with the naked eye or under a microscope. There are all sorts of features that turn both the beautiful and the boring of the fungal world into recognizable species. Where you or I just see cap and stem and gills, Bryn makes fine distinctions. There’s an overall sense of the form of the mushroom that it takes years to develop.
Before I went for a walk (or many walks, that is) in the woods with a mycologist, I wasn’t really aware of the sculptural quality of mushrooms. Now I have an appreciation for the beauty of their overall shapes and textures. But Bryn’s brain is like a code reader. From a distance he can judge if that tiny little thing on the log is a Marasmius or Mycena, based on the shape of the pileus (the cap), the width and bow of the stipe (the stem), and other general impressions that he probably cannot even articulate—the tacit knowledge that the scientist gains from years of direct experience.
Take a closer look now. Is the surface of the pileus velutinous (velvety) or glabrous (smooth)? Is it rugulose (wrinkled), pitted, or cracked? Better yet, it could be glutinous and covered in slime.
Does the stipe have any interesting features, like a finely netted reticulation or patchy raised “scabers”? You might break a little piece of the pileus off with your fingernail and try to peel the top surface off—whether it peels easily is yet another field character.
Look under the pileus, and if there are gills, make a small slice through them with your knife: Does a white, yellow, red, or blue latex ooze out? Does it change color once the air oxidizes it? Keep an eye for color changes on the flesh of the mushroom as well. Is the pileus or stipe bruised where you have held the mushroom? Bluing reactions can be especially impressive, as you can see below.
Or perhaps it looks like a sponge, like you see on the left. Microscopically, the underside of the pileus is one of the most important parts of the mushroom, because this is where the reproductive cells are located. The sponge you see (look—a well-fed beetle larva just crawled out of one of the pores!) is made up of thousands of little tubes, packed in together. Like the gills, these tubes exist solely as the means to spread the mushroom’s spores. You may see a tint of color on the gills or pores here that hint at the color of the spores, which can be a very important character. The spores themselves can be extremely beautiful, but you won’t get a really good look at them until you are back in the lab with your microscope.
Mushrooms may also identified using chemical characters. Some chemical tests must be done in the lab with droppers full of reagents that turn different mushrooms different colors; but there are plenty of chemical characters that can be tested right here in the field. The nose knows—and Bryn has an impressive nose, in both form and function! Does the mushroom smell raphanoid (like a radish or watermelon rind)? Or perhaps it smells like camphor or almonds or even like rotting flesh? Some mushrooms must be tasted to be understood, so beware the mycologist that hands you a tiny piece of fungus to taste in the field. It’s unlikely that he is trying to poison you, but he might be giving you a chunk of an acrid Lactarius that tastes as if you are chewing some especially hot peppercorns!
As you have learned, workaday mycology begins outside, in direct contact with the natural world. The attention that you paid to the forest around you and the detailed observations that you have made of the very fine Tylopilus that you found will pay off in dividends in the future. First, there is a cumulative benefit to be gained from today’s time in the forest. This is the practice of natural history: You draw continually from the knowledge that you’ve gained in past experiences in nature and in your study of others’ work, and you synthesize that knowledge with your immediate experience of the world around you today.
But what’s next for today? Fortunately, Bryn’s ready with a snappy mycological aphorisms for just this kind of occasion: Flash it, Smash it, and Dry it.
“Flash it” is probably obvious: You must photograph your mushroom both before and after you collect it. Get a nice picture in the field, showing the substrate on which it was growing, and later take a more artificial photo against a neutral background, to record color and scale, and morphological details.
“Smash it” is Bryn’s method of DNA collection. Once upon a time we carried tiny little plastic tubes with preservative liquids into the field, into which we would plunge a fragment of each mushroom’s gills or pores. Now the very same reproductive tissue gets smashed into a fancy kind of paper that preserves the DNA in a much more convenient form. Bryn has even made a very informative video of this method.
That last step, “Dry it,” kind of ruins the rhyme, but there’s no way around it, you can’t change what happens in a food dehydrator. Before that lovely Tylopilus nigerrimus starts to deliquesce, better dry it out as soon as possible.
Now that you have flashed, smashed, and dried your mushroom, you’re ready to take your impressive knowledge of that mushroom’s natural history into the laboratory. Scientists who work with DNA may be derided as “gene jockeys” when they have a myopic focus on DNA, at the expense of seeing the whole organism. But you are already well on your way to becoming a natural historian and I know you won’t lose sight of that whole living mushroom and its associated tree when you finally get a peek at its DNA.
Making tracks in the wilderness
March 7th, 2011
By Rachel Mason Dentinger
In the sparkling new visitor’s center here at Gunung Mulu National Park in Borneo, an introductory film runs all day long, describing the unique limestone formations of the park, a million bats leaving the Deer Cave each night, the forest types and fauna of the park, and its recent designation as a UNESCO World Heritage Site. Gunung Mulu, it intones, was a “trackless wilderness” before the park was formed in 1974. And for the purposes of the tourist industry, that was indeed the case. But for the local indigenous people, the settled Berawan who hunted in the area and the nomadic Penan, for whom Mulu was home, the “wilderness” was constrained even back then by paths.
I have been trying to picture these people subsisting in the forest around us and I still find, even after two weeks here, that my imagination is circumscribed by the civilized constructions that make the setting for the daily stuff of our lives here; eating in a café, sleeping in a climate-controlled room, walking on boardwalks. I am aided by books written by previous visitors to this part of Sarawak, scientists who have provided photographs of Penan and Berawan as they were when this park was formed, almost four decades ago. These give me a feeling of connection to them, for their faces are recognizable—they are certainly the ancestors of the people who work in the park today.
The shape of a jawline or brow reminds me of a park guide, the stretched earlobes that were once very common here remind me of an elderly craftswoman we met at a nearby market. The photos show men in loincloths with tubes at their waist holding arrows for their blow-guns. The women and girls wear sarongs, often only from the waist down, and I can’t help but imagine looking down to find a terrestrial leech (in addition to the rather large human leech that I already sustain!) on my breast.
The young Penan and Berawan who work in the park today, for all their facial resemblance to these grainy photographs, wear tight sloganed t-shirts and skinny jeans, and play badly aging club mixes on the café soundsystem when the park director isn’t paying attention. Despite this discordance with our romanticized touristic notions of indigenous life, we have been granted a few chances to see the lingering influences of their cultural roots.
These chances have almost all come at a remove from the intense management of the park headquarters. In order to find mushrooms, Bryn and his colleagues here have organized a number of trips to the outlying park “camps.” These are rustic structures, placed at critical junctures along the main hiking trails, some of which were built in 1977 and 1978, during an extensive Royal Geographical Society expedition to the newly formed park. Most have no potable water or any real facilities to speak of: they are platform with roofs, completed by cookstoves run on butane that must be hiked in to the camp. To carry the cans of butane, as well as everything else you need to survive for your time at camp, you hire porters. The porters that we met ranged in age from 19 to 39, but there were certainly older ones that we passed—or rather, that passed us—on the trails.
These tough men (for they are all men) carry cases of Tiger beer, kilos of rice and noodles, tins of sardines and tuna, bottles of drinking water, and cans of butane all on their backs. And often enough, below their feet, they wear nothing! Where this tourist employs all the ergonomic technology that I can muster to protect my tender muscles and tendons from a burden, carrying a pack fitted out with 20 different adjustable straps, contoured, breathable straps and back padding, and a waist belt molded to fit the particular shape of my very own hips, a porter carries a woven rucksack, called a kiwa (also known as a selabit or kiba or kibi, in various other local dialects), that is virtually identical to the ones his ancestors carried many generations ago: two shoulder straps of flat, woven rattan; an absolutely flat, stiffly woven back plate; and loosely woven netting on the sides, which is then laced together with more plant fiber, to accommodate loads of myriad shapes and sizes. At one point on the trail, our entomologist friend Chris Darling needed a break from his own ergonomic hiking pack. Naturally, the porter could not bear to carry this carefully engineered abomination of a backpack, and crammed it instead into his kiwa and carried on as before.
It is thus that we stand aside, shamed if we thought we were really tough, and are passed, sometimes in two directions, by rapidly moving, nearly naked, barefoot guys with 20-30 kilos strapped to their backs. Off the beaten path—that is, off the raised wooden path, really—the trails are generally quite muddy. They may also be rocky and steep, though the steep ones usually have the benefit of rooted stairs, the natural flights that form when rain and footfall repeatedly wear away the soil on a forested slope.
While the baby and I cannot really visit any of the more rudimentary camps, we had the pleasure of joining the scientists on a slightly tamer trek to Camp 5, a place that is more accessible, than the other camps. A boat ride reduces the walking distance to 8 km. Sleeping mats make for much more comfortable nights. And the value of a small staff that keeps plenty of water boiled for drinking is self-evident.
The boat ride was one of the highlights for me and for the baby, who gets excited every time he sees a longboat or hears—and then mimics!—an engine buzz by the headquarters, just below the café. Along the river, you see the scattered settlements of locals, for whom the river is life. This seems like an obvious statement, for all humans tend to concentrate themselves near water. But in a lowland tropical rainforest, the river is more than just an efficient means of transport—it is the connection to world beyond walking distance. And walking distance means something different here, even for those accustomed to the rainforest; humans need trails, and to blaze a trail here in the era before chainsaws would have been both challenging and dangerous.
Which brings me back to that trackless wilderness. Even today indigenous Borneans impress in their ability to negotiate the rainforest. But by its very existence, this cultural heritage, of familiarity with and experience in the wilderness, belies the notion of the wilderness itself, now or 40 years ago. When the researchers for the Royal Geographical Society expedition arrived here in 1977, it was a matter of hours before they found the remains of their first Penan settlement, clearly abandoned only days before their arrival. Soon enough, exploring the nearby forest, they began to suspect that some of the forest was secondary growth. In other words, parts of the forest had already been farmed and then abandoned, left for the forest to reclaim. The head of this expedition recounts how he and a companion toiled, breaking a trail into a part of the forest they believed had never been visited by humans. They broke through dense vegetation into a clearing with a stream, only to find two young Penan children splashing unconcernedly in the water—children they knew, in fact, because their family had settled near the researchers’ longhouse.
So, for all my previous pondering of “apartness” from nature and “immersion” in nature, I must admit, I do not really know what even I mean myself by “nature.” The wilderness is full of mysterious, hidden lives, including those of humans; and even without raised wooden walkways, it is also full of tracks. We humans perambulate, packing our babies and belongings up in woven rucksacks, moving from place to place, following food and opportunity. And making tracks in the wilderness that lead home means that the wilderness has been, in a literal sense, domesticated.
Holding nature at bay in the tourists’ 10%
February 26th, 2011
By Rachel Mason Dentinger
For the past week, my husband and one-year-old son have been on the island of Borneo, exploring Gunung Mulu National Park. “Gunung” means “mountain” in Malay, thus the park is anchored by Mount Mulu. Mulu’s presence above us is felt more than it is seen; it’s no volcanic Mount Hood or Rainier. Instead, it’s a low, forested shrug of sandstone, a holdout in the midst of the softer limestone, which has acquiesced around it, surrendering to the persuasions of rain and air and sunlight (and then more rain) in the millennia since the seafloor was elevated, forming Borneo.
This is Sarawak, one of the Malaysian states of Borneo, a region most noteworthy (to me, at least!) for its importance in the work of Alfred Russel Wallace, the Victorian naturalist who is remembered as the co-originator (with Darwin, of course) of the theory of natural selection. Perhaps this is one reason why my very first impression of this place is that it has been tamed, even manicured. For me, Sarawak is the setting for an evolutionary drama, a touchstone for the notion of the “entangled bank” itself. But from where I sit, Mulu’s wildness seems constrained or, more accurately, excluded: barred from the air-conditioned bungalows and raised boardwalk trails, from a set of constructed human spaces carefully designed to allow the visitor to view nature without getting her feet muddy.
But already I have to qualify the gross generalizations I made above. Of course I am sitting in relatively artificial luxury. After all, we are now traveling with a toddler, and my husband Bryn and I have made some concessions in order to feel comfortable taking him to Borneo. Nobody forced us to choose the air-conditioned bungalow over the open-air hostel or even the longhouse room with a ceiling fan. And nobody is preventing us from hiking many kilometers out into the park to find a spelunking adventure in one of the many remote limestone caves. In fact, Bryn just returned from a trek to an outpost of the park’s trail system, a day’s hike away, where he collected mushrooms while the baby and I chilled down here at headquarters. Yes, nature may be found unfiltered here if you are willing to get a little muddy. The truth about me right now? I don’t mind avoiding the mud.
But my basic observation remains true; only a fragment of Gunung Mulu National Park is accessible to tourists, and that part, even at its most raw, is highly managed. Undoubtedly this management serves to protect the entire park, including the uncharted wilderness area that constitutes the other 90% of Mulu. Funneling people smoothly through the tourists’ 10% protects the entirety. Raised walkways prevent people from striking off into the forest, damaging wildlife and possibly themselves in the process. And the very existence of wilderness can be supported—financially and socially—if the park is otherwise self-sustaining. Tellingly, the government of Sarawak has hired a private firm to manage the 10%. Recent construction in the area of the headquarters, where most of park’s lodging is concentrated, attests to a desire to make the park more like a resort. Take the spacious, air-conditioned, verandaed bungalow where we are currently staying: housekeeping visits us every day and makes our beds and replaces the complimentary coffee. Water from the Sungai Melinau (Melinau River) is treated and, according to one park official, 4-5 hours per day are spent making sure that it’s potable. After all, he told me, “sick people are bad for business.” So, indeed, nature here has become a business—and perhaps for good reason.
However, the management philosophy of Gunung Mulu dates back much farther than the construction of this bungalow or the multiplication of food options in the new open-air dining room overlooking the Melinau. If you have ever hiked in the lowland tropical rainforest of the Osa Peninsula in Costa Rica or crossed a river in the cloudforest at Reserva Los Cedros in the Ecuadorian highlands, the first thing that will drop your jaw is the kilometer upon kilometer of paved, boardwalked, and stair-spangled trails through the forest and over and through the limestone cliff-faces.
Bryn, who has worked elsewhere in Malaysia and in Vietnam, says that the trail system reflects a Southeast Asian style of park management. It’s interesting to put Mulu in that regional context, but what about the history of this particular park? In the mid-70s, Mulu was an almost complete wilderness, peopled only by scattered populations of Penan, a nomadic indigenous people. Today, there’s an airport, a resort, and a fancy new park headquarters complex with an extensive system of boardwalks. The location and design of all of these constructions are explained in part by the simple desire to capitalize on people’s interest in the park, especially the very cool bat caves, which provide the central tourist attraction. But simple calculations of profit do not explain the effort that has gone into building and maintenance.
Take the trail system. Raised boardwalks are in some places necessary, because parts of the forest are often flooded, making accessibility as issue. (Let’s not question the necessity of crossing the flooded forest for the moment.) An even more interesting accessibility issue: wheelchairs! I seriously doubt that this is what the park management had in mind when they started constructing boardwalks, but we have seen a gentleman in a wheelchair enjoying the park since we arrived.
Apart from raising the visitor above standing pools of water, however, quite a bit of the trails are low boardwalk or even concrete. As far as I can see, this serves at least two purposes. First, it channels visitors through a particular part of the park, making us loath to explore the forest for ourselves, thus reducing our potential damage to organisms in the park through carelessness. The very surface of the trails, while requiring maintenance and even apparently cleaning (Groups of people walk through the forest with brooms, sweeping fallen leaves off the trail—no joke! More extremely, another visiting researcher claims they even powerwash the trails.), is not subject to erosion, and is more resistant to the impact of hiking boots tromping through the forest in that heavy touristic way.
The second purpose this trail system serves is to hold nature at bay, to protect us from its dangers, both real and imagined. No question, I dread the day I look down at my baby and see a terrestrial leech stuck to his ankle. Keep those suckers far away from me. And as for imagined dangers, these are perhaps the most serious! Look, I know that wild pigs really should be the least of my concerns when I am walking through the Amazon basin. Heck, I would have been lucky to see wild pigs. But I will reveal right now that I spent an inordinate time in the Amazon snuffling the air quite dramatically anytime I detected a tiny whiff of animal odor, already searching in panic for a tree to climb. And when I see pictures of the bearded pig present in this park? Well, I am very glad to be elevated above the trail.
Even when I am not elevated above the forest, I sense an obvious apartness that is absent when my hiking boots touch soil. It bothers me intensely to miss out on the sensory immersion that I have come to expect from a walk through a tropical rainforest. Nevertheless, as I travel now with a one-year old on my back, and especially when I let him practice his own slightly wobbly walk, I have to admit that I don’t always mind feeling a bit apart.
Have I traded in experiencing nature for merely viewing it?
What’s sexier than sex and warfare? Taking the “arms race” one turn too far.
March 25th, 2009
By Rachel Mason Dentinger
Talk about sexy science. How could any science be any sexier than sexual selection?
Then combine sexual selection with “nature’s arms race,” and what do you get? Science so titillating that even a seasoned science journalist might get a little…carried away.
This was the only explanation I could contrive yesterday morning after I read Nicholas Wade’s latest contribution to the New York Times Tuesday Science section. Only last week I posted about the importance of the arms race analogy to my dissertation research on the history of coevolutionary research. So I was very excited to see Wade’s piece, “Extravagant Results of Nature’s Arms Race,” gracing the cover of the Science Times.
Sexual selection is not really my bag—the evolutionary “arms races” that I write about are between hungry herbivores and unpalatable plants, not males of the same species. But the general concept is the same: offense and defense is heightened over many generations as a result of natural selection for the best-fed herbivore, or the least palatable plant, or, in the case of the sexual selection, the most successful (read: sexiest) male.
Sexual selection is a special case of natural selection where the most successful features do not always seem obviously adaptive. Take the classic example, the peacock’s plumage. Its lavishness makes no sense when you imagine the peacock trying to outrun a tiger. What can be more evolutionarily important than avoiding being eaten? Being sexy, of course. At some point in evolutionary history, females developed a preference for gaudy tails, and since the males with the gaudiest tails were the ones getting the action, more pretty boys in the next generation had gaudy tails. And so on– you get the picture.
This “female choice” type of sexual selection does involve an “arms race” of sorts: Peahens’ preference for gaudy tails escalates even as the gaudiness of male tails escalates—female preference and male success mutually reinforce and drive each other to greater extremes.
But invoking the “arms race” seems a lot more convincing when you are talking about out-and-out evolutionary combat. The second type of sexual selection, “male-male competition” is all about the escalating evolution of better and better weapons. In some species, males actually fight for sex, as with these male elephant seals battling for control of a harem of females. But in other species, it’s enough to look big and scary, to intimidate the other guy before he even tries to fight you. If your antlers are large, you might fight other males and win. But if your antlers are humongous? You could be king of the lek without ever having to tangle. Possible bonus: Your “armament” may also serve as an “ornament” if females find your big antlers sexy. These University of Minnesota researchers found that lion’s manes did double duty, attracting females AND intimidating other males.
For your viewing pleasure, the piece focuses especially on the dramatically beautiful “horns” of dung beetles. And, as in most profiles of sexy science, Wade could not resist taking the next step, pushing toward that ultimate climax of sexy science.
What’s sexier than sex and warfare?
Sex and warfare and humans, of course:
“People have pathetically puny teeth and claws compared with the armaments of other dominant species. This is a sign not of pacific intent but of the fact that they manufacture their weapons.”
In other words, the “arms race” is more than just a metaphor that allows us to comprehend the evolution of elaborate organic weaponry on our own terms, those of technological weaponry. It’s an analogy between human and nonhuman evolved features.
If you read what I wrote about analogies last week, you’ll know that when evolutionary biologists posit such an analogy, they are claiming that evolved tusks and manufactured guns were generated in response to the same selective pressures. They have different evolutionary histories–in this case, the difference is even more extreme, since one has a biological evolutionary history and the other has a cultural evolutionary history. But they are analogous because they share an adaptive function.
I am most fascinated by analogies like these, which effectively blur the boundary between biological evolution and cultural evolution. But it’s not just the boundary between biology and culture that becomes a bit blurry here. Wade interviewed a primatologist who claimed that it’s “very reasonable to assume that, as humans evolved and our culture became more complex, skills in tool making or other cultural behaviors took over from anatomical traits as ‘markers’ of a male’s competitive skill.” In other words, the proposed mechanism for such a shift is also kind of hazy. Claiming that cultural evolution just “took over” from biological evolution is not exactly a substitute for a testable hypothesis.
In any case, whether or not you think this is a reasonable assumption, you have to admit that it’s very compelling. Analogies are compelling—that’s why they are so useful. They motivate us to make analytical leaps that, in the best of scientific circumstances, may also be empirically verified.
Sometimes those gravity-defying leaps also defy logic, however. Even a seasoned science journalist like Nicholas Wade may be seduced by sexy analogies into making such a logic-defying leap.
Wade analogizes between the organic “weaponry” featured in Dr. Emlen’s paper and a samurai helmet or a crossbow. So far, so good—these could make sense within the context of sexual selection.
Then, suddenly, Wade leaps into the geopolitical domain of the “menacing tanks and rockets that paraded through Red Square in Moscow in the days of the Soviet Union.” This is where the allure of the arms-race analogy becomes dangerous. Was the Cold War a result of sexual competition? Is the “the advent of chemical, biological and nuclear arsenals” really relevant to a piece on male-male competition?
The arms-race analogy has been scientifically productive, helping biologists imagine a series of evolutionary interactions that mimic the military escalation of the Cold War. But when it leads us to relate sexual selection to global politics, it has probably overreached the limits of its utility. And when this overreaching happens on the cover of the Science Times, we must take pause.
Evocative analogies are powerful tools and—just like that nuclear arsenal—they should be used only with the greatest of caution.