Archive for the ‘history of science’ Category

Make an analogy between humans and cockroaches and then read this posting.

Friday, March 13th, 2009

At this moment in my dissertation work, I am transcribing my two-hour interview with ecologist Daniel H. Janzen.  In early December 2007 I flew to Philly and stayed there for one night, interviewing Janzen in his office at the University of Pennsylvania just 6 hours before I flew back to Toronto.  Clearly, I have waited far too long to transcribe the interview, which is typical of me.  I am always excited to rediscover what I learned during an interview.  Somehow I manage to forget almost everything we discussed in the minute after an interview ends—it’s as if my intense relief that it’s over triggers some sort of spontaneous amnesia.  So there are always many pleasant (and some excruciatingly embarrassing) surprises awaiting me.  But I find the process of the transcription totally grueling.  I really try to get every “um” and “ah” and grammatically disastrous sentence recorded for posterity, and this requires a lot of rewinding.  In the case of Janzen, who sprints from topic to topic in a rusty Minnesotan accent, rarely pausing for the insertion of a period or comma, my rate of transcription slows down considerably.  Not to mention that there are so many more words per minute in this interview.  I am 1 hour and 36 minutes into this interview and I have a 15-page transcript already.

There is a lot of good stuff here.  There’s an absolutely incredible story about botanist G. Ledyard Stebbins, who purportedly slept through Janzen’s thesis defense, but woke up just in time to compare the ants that Janzen studied to the chemical defenses that other plants produce, which protect them against attack by herbivorous insects.

At that moment, Stebbins gave Janzen what would become one of his most persuasive analogies.

My (point-and-shoot) pics of ant acacias from Santa Rosa National Park in Costa Rica (2006)

My (point-and-shoot) pics of ant acacias from Santa Rosa National Park in Costa Rica (2006)

Some background will help you understand this analogy.  Janzen’s dissertation research in Mexico exhaustively detailed the mutualistic relationship between “bull’s-horn” acacias and acacia ants.  As a graduate student in entomology at Berkeley, his first notion was just to study these ants—why were they so bizarrely fond of these prickly acacia trees?  It was by chance, or at least “serendipity,” that his attention shifted to the relationship between the ants and the acacia tree.  In his thesis, he concluded that there is a real mutual reliance between the two species.  The ants cannot live without the acacias: they take shelter and breed in the acacia’s oversized thorns and feed from the plant’s nectaries and Beltian bodies (little nutritive tabs that grow at the leaftips of the acacia).  Conversely, acacias that grow without a resident ant population rarely thrive. Without the ants to fight off other insects and the choking lianas that like to drape themselves across other plants, the acacia falls prey to both herbivory and competition with other plants.

Now, Janzen was not, by any means, the first to turn his attention to this surprising relationship.  Thomas Belt, a 19th-century British mining engineering who worked in Nicaragua for years, called the ants a “standing army” that defends the acacias against their enemies.   Harvard entomologist William Morton Wheeler challenged the claim that the ants were protecting the acacias, writing in the early 20th century that plants needed ants like a dog needs fleas.  Strong words, gentleman!  A raging academic debate that did not subside till Dan Janzen’s paper, “Coevolution of Mutualism Between Ants and Acacias in Central America,” published in the journal Evolution in 1966.

One of the things I’ve always loved about evolutionary biology is the evocative language that biologists use to describe processes and relationships.  Are the ants a “standing army” or a pack of voracious sap-sucking fleas?  Gives you two pretty distinct ecological pictures, right?

The study of coevolution between plants and insects has been built upon suggestive language like this.  This was a field that came into being during the Cold War, so who could really resist using the term “arms race” to describe the back-and-forth evolutionary responses between plants and insects?  Plants escalate their toxic biochemical defenses against hungry herbivorous insects, and insects escalate the tools they use to overcome those defenses.

So, what does it mean to claim that acacia ants function just like the chemical defenses used by other plants to fend off the insects that would eat them?  First, this analogy crosses categories: the ants, organisms in their own right, become (merely?) evolutionary adaptations of the acacias.  The ants are, Janzen would claim, an extension of the plant’s genome—in the same way that human technologies are extensions of our genome (which he also claims).  In essence, then, the ants become an adaptive technology.

But an analogy always operates in two directions.  The reciprocal effect is to grant the chemicals produced by plants a new identity.  The best analogies (just like the best metaphors) associate entities that seem, otherwise, completely dissimilar.  In this case, the analogy between ants and plant chemicals breaks a long-accepted boundary between what animals can do and what plants can do—or, rather, what plants can’t do, passive pieces of green furniture that they are.

I mean, when we talk about animals, we use active verbs.  We see them causing things to happen, acting—in short—with agency, if not intentionality.  Plants, on the other hand, when they’re not simply invisible, don’t tend to act.  They don’t move, they have no sensory organs.  Even when we see them, we don’t think of them as agents.   Even when a plant has an effect on its environment, it appears somehow passive, and the effect is often considered a by-product of some other more planty function.

Coevolutionary analogies, by contrast, make plants and animals equal partners.  More accurately, they’re adversaries. And plants, so long seen as the wallpaper of the world, suddenly become embattled veterans of an ancient chemical war with animals.

This kind of transmission of meaning and agency between plants and animals has real effects on science (this is one of the themes of my dissertation).  It’s one reason that I became so interested in Janzen.  The man analogizes like it’s going out of style.

More importantly, he is very careful to distinguish between “analogy” and “metaphor.”  Janzen does not speak in metaphors, because metaphors make comparisons that could not be literally true.  If he makes a comparison between, say, armyworms gobbling up an entire field of corn and Germany invading Poland, he does not mean this comparison metaphorically.  To him, hungry caterpillars and power-hungry humans are the same thing. The entities interacting are unimportant: locusts or leopards, hummingbirds or humans, it doesn’t matter—only the interactions themselves are important.

Janzen describes this as a fundamentally ecological perspective on the world, but I see it as a fundamentally evolutionary perspective, instead. In evolutionary biology, limbs or organs are analogous when they perform the same biologically adaptive function but have different evolutionary origins.  When Janzen draws an analogy between human warfare and plant-insect warfare, this is also what he means: same adaptive function, different evolutionary origin.

Ants or wild parsnips, humans or cockroaches—we might organize them into different categories, but evolutionarily, they are all subject to the same forces.  It’s part of what gives evolutionary biology its explanatory power.  And also, let’s face it, what makes it so darn fascinating.

This is one good-looking cockroach, right?  Also from Santa Rosa National Park.

This is one good-looking cockroach, right? Also from Santa Rosa National Park.

On really striking out and (sometimes) striking el oro

Tuesday, February 24th, 2009

About luck. The notion has been irritating me for the past few days. I’ve always been interested in how chance operates in my own life. Like most people, I usually construct a nice satisfying retrospective narrative about my life. But chance has always played an unsettling starring role, throwing a wrench in the aesthetics of that erstwhile smooth story arc—you know, the one where I make wise conscious decisions and directly control the events of my own existence?

My sense of the importance of chance has only been heightened in my dissertation research, in observing its importance in the lives of pretty prominent scientists. This is not just the historian’s impartial eye, observing how life deals different hands to different players. This is the witness borne by those players themselves! Renowned biologists—known for their brilliance and not, typically, for their humility—have repeatedly credited chance with the paths of their careers. Paul Ehrlich. Dan Janzen. These guys have taken unusual and sometimes unpopular stances on ecological issues—in other words, they give the impression of deliberately charting their own courses. And yet, Janzen loves the words “serendipity” and “serendipitous,” and applies them liberally to the story of his own career.

Of course, when Janzen speaks of “serendipitously” stumbling upon an ant acacia while roving across Costa Rica in the early 1960s, he is not talking about pure chance. He is talking about the convergence of luck and preparation; the effect of a particular experience upon a mind primed with just the right kind of knowledge and previous experiences. The true luck is almost always in the timing of that critical experience.

Like Janzen, we’ve been doing some roving across the Costa Rican landscape, hoping for such a lucky convergence. We have no concrete information directing our mushroom search at the moment; only a knowledge of the general rainfall patterns for the season and a sense of where oak trees might be found.

Walking along a forest trail during the dry season might remind you of autumn in North America. Deciduous trees lose their leaves here just as they do in the temperate zone—it just happens to be during the “summer,” the drier and sunnier time of year. According to the Costa Rican bird Bible, Skutch and Stiles’  Birds of Costa Rica, it was the Spanish that declared the dry season summer, arriving with their memories of a hot and dry verano and cool and wet invierno.

If you’re lucky enough to have made it to an oak-dominated forest, however, you might still look up and see a truly regal canopy above your head. These oaks are closely related to the evergreen live oaks of the Southern U.S. And while “regal” might seem a cliché, under the circumstances, it’s spot-on. The oaks we have seen here are hundreds of years old, many feet in diameter, and verdantly populated with mosses, lichens, and bromeliads. There’s something so vital about the silhouette of an oak tree. The leaves burst so densely from the awkward joints of its branches. Its body looks haphazardly assembled and, at the same time, absolutely coherent. Coherence is a concept, but I would even say that an oak tree is cohesive, in a purely physical sense, as if it is gathering its deep green pigmentation along with moisture and light and a body of cool air, directly from the air around it. When each branch supports a dozen bromeliads, and their bright fuchsia and maroon and yellow-green leaves glowing translucently from above, this sense of pure organic gravity, of substance and sustenance, is intensified.

Rhapsodies over the beauty of oak trees, however, do not a successful collecting trip make! Oak trees are also mycorrhizal symbionts, living in intimate collusion with fungi, whose hair-like mycelia connect with their roots underground, sharing nutrients and minerals in an exchange that sustains both tree and fungus. Finding an oak means finding its fungal symbionts, which, if we’re lucky, have fruited above ground, producing those reproductive organs that my dear husband so desperately seeks: mushrooms.

This is where serendipity comes in. There are thousands of acres of forest reserve and national park in Costa Rica. Most of this is completely inaccessible, or else only moderately accessible, especially for people that need to collect mushrooms, photograph them immaculately, in situ and against a gray background with an herbarium collection number, take DNA samples (because this is, after all, part of a DNA barcoding project), and then dry them completely in a food dehydrator. So, via various points of entry, public, private, and otherwise (meaning, we’re not quite sure who owns the land or the road by which we reach it), we try to get at this inaccessible core of forest.

For our purposes then, these roads and trails are essentially random cuts in the forest. We can steer ourselves toward higher altitudes, where oaks and other mycorrhizal tree species are more common, or toward the rainiest provinces, but the decisions made decades ago to build a trail along this ridgeline or blast a switchback for the road into that hillside, may or may not take us precisely where the mushrooms just happen to be fruiting today. As much we have prepared for this trip, there will always be the discomfiting suspicion that somewhere—maybe even just a measly kilometer to the east or the south—the mother lode of mushrooms is elbowing its way up through soil and detritus, where we will never find it.

Anyway, that’s how it feels today. Fieldwork, especially when the task is opportunistic collecting in an attempt to document fungal diversity in the region, can sometimes boil down completely to luck. And luck is not with us in other ways, as well. We are three days into this collecting trip and have yet to see the collection and export permits for the mushrooms we are supposed to be collecting. Bryn started the process of applying for these permits more than two months ago, at the moment he knew that his teaching trip would be extended into a collecting trip. Unfortunately however, the term “process” implies that there is a straightforward method for obtaining such permisos. In reality, successfully scoring a permit turns mostly upon finding a reliable contact on the ground, a contact who also has a functional working relationship with the relevant bureaucratic body. It’s not entirely clear what went wrong, but it seems to be a little bit of a failure in both aspects (maybe more heavily the former than the later, I might add).

In any case, we have not yet been able to collect in Parque Nacional Tapantí-Macizo de la Muerte, as we do not have the relevant permits. So, we are reduced to making even more random forays into the landscape, in hopes of finding mushrooms on land where park rangers are not likely to be breathing down our necks. This morning, over weak coffee (Costa Rica is a coffee-producing nation that reserves its most drinkable beans for export and tends to disappoint the palate with weak and bitter brews in person.), Bryn identified a small “protection zone” called Cuenca Rio Tuis, perhaps a couple of hours drive from our hotel in the small village of Orosi. It seemed a little far away, but also unlikely to be heavily monitored, and according to our topographical map, it reaches a peak elevation of 1963 meters and may even have oaks.

It was a lovely drive, on a fantastically sunny day, over mountainside roads that rapidly drop and fall while they and around Lake Cachí. Everywhere that we drove, a brief wave or a “Buenas!” out the window of our car transformed that standard hard-edged impersonal glance you turn toward a strange car into smiles—people are incredibly nice to strange gringos blowing unexpectedly through their tiny little hamlets.

coffee plantation

At first, at the higher elevations, we drove through coffee plantations. Coffee is Costa Rica’s grano de oro, “grain of gold,” which brought prosperity to this nation named “rich coast.” Workers alongside the road were spraying the beans with a pesticide. These workers are, reportedly, mostly Nicaraguans, since Costa Ricans are no longer willing to lower themselves to earning something like $1/bushel for picking el grano de oro. The shade-grown varieties actually appear to receive a good deal of sunlight, especially since many of the scattered trees planted to give them shade are deciduous, with only bare branches remaining, which cast crooked shadows (if not actual shade) over the coffee. Other plots are stocked with imported eucalyptus, trees that at least retain their leaves during the dry season.

dscn0249Halfway through the drive we made delicious tomate, aguacate, y queso fresco sandwiches for ourselves at the roadside. At lower elevations we began to see the sugarcane fields, where men with machetes hacked away at their stalks. Near the end of the day we passed a plant where trucks full of sugarcane stalks pulled in for processing. The men trailed down the roads slowly in the wake of the trucks, looking exhausted, machetes still in hand, while a smoggy burnt-caramel smoke filled the Orosi valley.sugarcane truck

Finally we reached our little forest reserve. Or…..we’re pretty sure that we did. After all, most of the roads are not signed and the GPS is often little help in finding our position on what seems to be a pretty imperfect map (it’s missing an entire huge lake?!). Driving into the reserve on the potholed dirt road through increasingly tiny villages (where people seemed even friendlier, in inverse proportion to the size of their towns), we started to get excited about the wooded hills that we could see ahead. When a road winds around so much, you really just have to keep faith that eventually you will reach that mirage of forest on the horizon.

abandoned houseWe passed a couple of abandoned house, one with half-collapsed porticoes and arches and windows that still contained shards of glass. We’ve tried to decipher graffiti from the side of the building, but it’s hard to read from my passing photograph: Aqui es solamente / No se aqui que / porque aqui.” Bryn says I’m wasting my time trying to read this nonsense, like a bathroom wall in the basement of some bar in Toronto. It’s something like: “Here is only / I don’t know here what / why here.” Indeed.

Anyway, eventually, we had to turn on the 4-wheel drive to cross a little river with steep embankments on either side and a little catarata (waterfall) in the center. But we never got much higher, and we never got much closer to that elusive deep core of forest. We drove as far as we could on the road, to a place where the mud was ridged so deeply in a sharp turn that we couldn’t imagine the car handling both challenges simultaneously. So we did a little bit on foot. And it was disappointing mycologically.

But for me, with the mud on my boots, and the humidity that layered my face in sweat the moment I started to climb the steep trail along the hillside, and my first glimpse of something as common as a bird-of-paradise flower—all of these started to melt that icy nucleus of Torontonian slush and snow at my center. Running my hand along a mossy boulder, I had a tempting moment of synesthesia, and I was certain that I could taste the deep green in the blade of a bromeliad just above my head. So, although we struck out mycological today, I feel finally that I have really arrived in Costa Rica, and I’m excited to try our luck again tomorrow.sunset drive back to Orosi

Darwin’s dirty little secret

Thursday, February 12th, 2009

An otherwise inspired tribute to natural history buries the fossils of Darwin’s theological ancestry and misses its chance to challenge Intelligent Design.

10-pound bill

When “Darwin: The Evolution Revolution” first opened at New York’s American Museum of Natural History in 2005, creationist critics were among its first visitors.  Reviews on Intelligent Design blogs found the show “biased” and “dogmatic,” and, even worse, burning with a “Darwinian fundamentalist” zeal.

What gives?  Thousands of visitors have already enjoyed this exhibit in New York, Chicago, Boston, and Toronto.  It’s currently on display at the Natural History Museum in London, as Britain gears up for the 200th anniversary celebration of Darwin’s birthday on the 12th of February.  Will hordes of visitors look back on the exhibit and remember what a hard time those doctrinaire Darwinians gave God?

I doubt it.  In fact, Intelligent Design will be the last thing on visitors’ minds as they reflect back on “Darwin.”  And frankly, I think that’s a shame.  If an exhibit about Darwin’s legacy is not the perfect place for biologists to face the Intelligent Design movement, then where will they do so?

This exhibit promises to unpack the wild and woolly head of one Charles Robert Darwin and, to a large extent, it delivers.  We meet Darwin in his privileged early-19th-century childhood, where he picked up the compulsive habit that would haunt him his entire life: Collecting the flotsam and jetsam of the English countryside when he should have been studying, making him a “scapegrace” according to his physician father.   But Darwin turned his disgrace into a virtue, learning to “look closely” at all of nature, mastering the ultimate “simple tools” of an authentic biologist, his own eyes.

These two themes of the exhibit, “Looking Closely” and “Simple Tools,” are put to elegant use, connecting visitors with the lived experiences of Darwin.  We peer through Darwin’s magnifying glass and stand in a replica of the study where he wrote the great tomes of his adulthood.  The exhibit shares iconic Darwinian stories, like his mad questing for beetles, which drove him once to “collect” a beetle in his mouth, for want of a free hand.  The beetle spewed an acrid repellant, an effective way to avoid being eaten, whether by a hungry bird or a desperate naturalist.  Paired with historical artifacts—in this case, beetles collected by Darwin himself—these stories bring him to life and reveal an intimate contact with nature, cultivated from childhood onward.

When I caught the exhibit last year at the Royal Ontario Museum (ROM) in Toronto, I had a chance to speak with its local curator, entomologist Chris Darling, who shares more than just a passion for insects with Darwin.  As a child, he too spent a lot of time outdoors, laying the experiential foundation for his life as a biologist.  According to Dr. Darling, an urgent concern addressed by the exhibit is “the demise of the naturalist,” the disappearance of biologists who concentrate as intensely as Darwin (who spent nearly a decade becoming the world’s expert on barnacles) while maintaining a broad base of knowledge and experience, observing and cross-referencing information from diverse sources.

And the exhibit certainly samples from many of these diverse sources, bringing home the enormity of Darwin’s accomplishment. That is, the synthesis of such a swarm of biological and textual information that most people would simply give up and go home.  In this exhibit you may catch African spurred tortoises mating, touch a replica of the giant extinct armadillo fossil that Darwin found in South America, and witness moments of startling insight, recorded in Darwin’s own hand, in an original research notebook.

Visitors to the ROM on opening day were dazzled by the dual quality of breadth and depth on display.  “How could you not be impressed by a man who acquired so much scientific knowledge during his life?” commented a young woman, an American tourist who proudly informed me of her Christian faith.  Another visitor, an aging Torontonian schoolteacher, struck by Darwin’s wealthy background, saw the exhibit as a demonstration of what can be accomplished by specialist scientists when they have sufficient resources to delve deeply into a topic. Natural history museums worldwide should applaud this exhibit for the case it makes in support of “Darwinian” science: Visitors see the value of collection and careful observation, and the ever-expanding catalogue of life that is the backbone of modern biology.

By contrast, the molecular tools that many of today’s evolutionary biologists use in their daily work merit no more than a cameo.  For this omission we can hardly blame the creators of the exhibit.  After all, “Darwin” is already packed with artifacts and ideas, and its creation must have been an excruciating surgery, where the organs excised seemed just as vital and vibrant as what remained.  Pride of place is rightly given to the specimens, tools, and documents of a Victorian naturalist.  Yet, despite the success of this central theme, the curators’ scalpels went astray when they carved away the history of Darwin’s theological education. What seemed like a vestigial organ to them—a useless bit left over from our ancient ancestors, like your appendix or coccyx—was more like Darwin’s carotid artery, the wellspring of some of his most important observations.

At the risk of sounding a lot like those complaining creationists, I protest: there wasn’t enough Intelligent Design in the exhibit!  And I’m not talking about bringing in the masterminds behind the Big Valley Creation Science Museum in Alberta to give “Darwin” a facelift.  Instead, I’m talking about the very heart of Darwin’s scientific training at Cambridge, natural theology, which took his love of “looking closely” at organisms and turned it into a scientific skill.

Instead, Darwin’s deepest scientific insights seem to arise de novo.  In its effort to depict Darwin as a revolutionary, the exhibit text implies that he was the first person to critically examine similarities between different species.  In “The World Before Darwin,” we are told that all species were considered “unconnected and unrelated.” The text asks, “Why didn’t more people grasp that similarities in skeletal structures—so clearly visible—were a clue that species are related?”

Why?  Because the best comparative anatomists of the day, Darwin’s own mentors and colleagues, saw the shared skeletal structures of different species, known as homologies, as evidence of God’s design, his master plan for the living world.  Darwin was able to challenge this view only because he had assimilated its lessons so fully.

When the young Darwin looked closely at the world, he saw those homologies just as clearly as his colleagues did, as evidence of design.  But like other good observers of his day, Darwin began to see the flaws in this approach.  If God were so intelligent, why would he give a bat’s wing, a human’s hand, and a whale’s flipper the same skeletal structure?  Didn’t he have the basic engineering chops to devise specialized designs, better suited to the job that each type of limb does?

As Darwin learned more about anatomy, collecting animals both extinct and extant, he came to see homology as evidence for evolution.  And he had no trouble convincing his colleagues, also students of natural theology, of the same. Today, homology still stands as one of the most vivid demonstrations of our evolutionary heritage.  Our human hands share a skeletal structure with a bat’s wings and a whale’s flipper because we all share an ancestor in the distant past.

Because of the visual power of homology, the exhibit relies on it as evidence for evolution more than once, making the absence of natural theology that much more regrettable.  In leaving out this part of Darwin’s story, the creators didn’t ditch a pesky detail only a historian could love.  They missed an opportunity to explain the early prehistory of Intelligent Design, which is basically, “Been there, done that.”

How can we explain this oversight?  It may be, as ROM CEO William Thorsell commented at a media preview, that “Darwin is still too hot to handle.”  After all, “even in Canada,” it was impossible to find corporate sponsorship to support the exhibit until nearly a week after its opening.  In seeing the controversial content on their hands, perhaps the exhibit’s creators decided that Darwin’s training in 19th-century “Intelligent Design” was better left unmentioned.

In portraying his religious sentiments as nearly nonexistent, they sanitized the exhibit of Darwin’s dirty little secret, his theological education. We learn that Darwin, who was trained as a clergyman at Cambridge, brought a swanky engraved German Bible on his five-year voyage around the world, along with his more practical pistol and “peacemaker” club.  Anyone who has studied Darwin’s letters could tell you that he was, in his own words, “a very poor German scholar,” an insight that confirms what is implied by this display case: the Bible was just an accoutrement of travel, perhaps more effective as a weapon than as a source of inspiration.

And how do today’s biologists deal with God?  In answer, a human-sized video screen simulates conversation with a number of prestigious biologists, a valiant attempt to create some kind of dialogue. But the conversation is one-sided. And guess who’s talking?  God-fearing head of the Human Genome Project, Francis Collins (not an evolutionary biologist), blandly assures us that faith and science are “complementary.” A nattily dressed engineering student described the video as “interesting” but hardly enlightening.  “It still leaves a lot of questions for me.  I don’t think I understand anything more about the controversy.”

Nearby, a biology textbook is displayed, branded with the kind of disclaimer sticker disseminated by the Intelligent Design movement, claiming that evolution is “only a theory.”  Another video tries to answer this challenge: scientists stand again in a featureless room, talking at the visitor, explaining that a “theory” in science is not merely a guess, but a critical “framework” within which facts are understood.

But these videos are all just talk.  Visitors have been told time and again, before they even arrived at the “Darwin” exhibit, that science is dynamic, self-correcting, allowing its most treasured principles to be toppled in the face of solid evidence.

Ironically, the story of natural theology, so carefully avoided in this exhibit, is a real-life account of just how such foundational concepts in science may be challenged. Though it is neither biased nor fundamentalist, as creationists claim, in overlooking the “Intelligent Design” in Darwin’s own intellectual history, this exhibit misses an authentic demonstration of the ideals it professes.  Worse, it sidesteps a meaningful discussion of Intelligent Design and why—as science—it just doesn’t cut it.