Yearly Archives: 2012

Trash whale

As Homo plasticus shambles its clumsy way through the world, pieces of junk slough off its body. Much of this exfoliated detritus finds its way to water. The sea is now comprised of water, plastic, and life, in that order.

A collaboration among scientists, artists, and engineers at Olympic College in Bremerton, Washington, holds these facts before us in a striking way. A three-month-old gray whale hangs in the gallery, its body made from plastic bags woven into the surface of a welded armature. The baby whale swims through a room strewn with one month’s worth of rubbish collected from the shoreline along a small sampling area in Puget Sound. Toys, tags, wrappers, cups, pieces of Styrofoam, bits of houses, syringes, bottles: the downstream remnants of our appetite for indestructible plastic stuff.

The whale reminds us that many parts of our oceans contain as many bits of floating plastic as plankton. Seabird guts are choked with these fragments. Dissections of the stomachs of beached gray whales show that they also ingest large quantities of plastic. Because they feed, in part, by scooping at the sea floor, their guts get populated not just by the floating plastic, but by heavy sunken objects. And here we find a surprise: golf balls, sitting like modern Jonahs in the guts of whales. Immediately I was transported out of the gallery, away from the coast and across the continent: back to the Tennessee woods, gazing at plastic globes in a mountain forest in Sewanee.

There is no escape, it seems, from the products of our re-creation.

[Special thanks to Susan Digby, geography professor at Olympic College, one of the whale’s creators, for opening the gallery after hours to give me and my friend Peter Wimberger a tour. You can read more about the project on the gallery’s website.]

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Forest on Whidbey Island, Washington

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An empire of moss and broadsword ferns. Douglas fir trees bend the sea wind. Reams of gold leaf — bigleaf maple — drop through thickets of hemlock and cedar.

Kinglets hammer the forest’s ceiling with sharp brads of sound. Then they drop, working the ferns. Ten of them, right here: hazed wings and stone-bright eyes. Sulfur headstripes; bright, they slice open the heavy green drapes.

Wads of old leaf caught in maple tree crotches, rotted mats lodged inside sprays of alder twigs. Seedlings take root there, above our heads. The soil’s upper boundary is fogged. In walking, we worm through soil passages, burrows of air.

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Savanna

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The photos above are from the savanna restoration site along the Mackinaw River at Merwin Preserve near Bloomington, Illinois. The site is managed by the ParkLands Foundation. The savanna portion of this natural area is maintained by periodic burning which thins the understory but keeps in place the mature trees. Illinois was, until settlement by Old World colonists, over ninety percent prairie and prairie-savanna. Now, about one tenth of a percent of the original habitat remains, and maybe one tenth of that is in “good shape.” So small islands of remnant habitat, such as the one we visited, serve both as reminders of the past and as critically important habitat for today’s native biodiversity.

All around, the land has been ploughed, revealing the famously productive soil that underlies the region. The soil is the color of dark chocolate. Just gazing at the soil made me hungry: here is land that can feed. The soil’s richness was built by the plants and animals of the prairie. But that very richness expelled these creators from most of the landscape. Now the former prairies grow corn and soy, in fields whose size is measured in thousands of acres. That food sustains many people and, lately, our cars. Nearly half of this year’s corn crop will be poured into gas tanks. So as we drive over this land to see its native species, we’re powered by the work of those species’ ancestors.

Even in its plowed state, central Illinois has an open beauty, a beauty that was magnified many times in the savanna itself. The wind loves that openness, so the sound of air against grass (whether prairie grass or corn) and trees (in savannas or in farm windbreaks) forms the acoustic frame for an experience of the land. And, like the soil, the wind now also powers our technology. Copses of wind turbines stand at the edge of town, hopeful new savannas, twisting electricity from the sky.

I am very grateful to Given Harper at Illinois Wesleyan University for arranging my visit. Thanks also to the students, staff and faculty for greeting me with such warmth.

Taking some contemptuous cross-fire. Disappointed.

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Wow. The NY Times piece about my book has inflamed some sensitive nerves out there. Jerry Coyne, a distinguished evolutionary biologist at the University of Chicago, has taken issue with part of the article, a so-called “drive-by diss” of Richard Dawkins (the Dawkins Foundation site has reposted Coyne’s attack). Further, Coyne argues that this diss was a craven attempt to gain readers. He writes:

What galls me is the increasing desire of people to gain credibility by a drive-by snipe at Dawkins’s materialism and atheism. There’s no need for that here, and no need to mention the man. Haskell is going for readership, pure and simple, and wants to get it by criticizing a well known atheist.

This saddens me and, to be honest, seems uncalled for. Coyne says that he has not read the book, so I would expect maybe just a touch more humility in his questioning of my ideas and perhaps the civility not to impute my motives. He also sticks his neck out and offers a critique of my writing (“breathless lubrications”) without having set eyes on the book. I’m disappointed that an honest and non-aggressive expression of a difference of opinion about a difficult philosophical question — the nature of the universe — should be greeted with such a vigorous and contemptuous slap-down.

For the record: Dawkins’ work is one the reasons I got into biology in the first place. But, yes, I personally stop short of the kind of full-blooded philosophical certainty that Dawkins has used in his writing. All this is evident in my writing and in the many interviews I’ve given lately. But none of this data was used, nor did Coyne stop to ask what I meant.

Drive-by diss, indeed.

[Correction: the first draft had an errant “a” added in the last paragraph which I have now removed.

Additions: For those who do not want to wade through the entire comments section, I have cut-and-pasted Jerry Coyne’s follow-up and my further comments below.

Coyne: I’m curious, though. Did you make that statement about Dawkins or not? Jerry Coyne

Haskell:

Hi Jerry,

Thanks for connecting here. I sure did say that I *suspect* that the universe (multiverse?) may consist of more than atoms re-arranging themselves. (If inherent value and “rights” exist, as you say in your post, then you’ve perhaps agreed — neither of those are made of atoms and both are pretty hard to pin down.) I also said that I do not buy the full Dawkins position on atheism. To suggest that this was an attempt to get readers is absurd — I had a multi-hour conversation with Jim Gorman about the book and biology, so of course we talked about the big questions in evolution and the world of ideas. Dawkins has outlined MANY of those big ideas and so I don’t think it is unreasonable for me to say that I disagree with him on some of them. Surely we’re allowed to have disagreements without getting slammed for being desperate book-sellers, bad writers, etc, etc. Especially when those disagreements are about things with such a history of being quite difficult.

I’d be happy to send a copy of the book. It is, in part, a book-long celebration of what it means to look at the world through evolutionary lens. You might like it. :)

Again, thanks for connecting here. I admire your work and have done for many years.

Haskell: Oh, I just saw the post on your website. Simple answer: no I did not DISS anyone. To diss is, as I understand it, to disrespect someone, treat them rudely.

Haskell (after several days of comments by others):

Thank you to everyone who has contributed comments here.

A few brief thoughts from my end of things:

1. Comment about atoms. Ethical claims (about species extinction, human rights, etc) are not, to my knowledge, fully derivable from the laws of physics, chemistry, or biology. Yet I “deeply suspect” some ethical claims reflect more than the passing whims of nervous systems and might, therefore, have some kind of objective nature. What that nature is, I do not know, but it seems unlikely to be made out of atoms. I’m the first to admit that the suspicions that I harbor might just be feelings in an evolved brain and nothing more. But perhaps not.

2. For those who want a single number on the Dawkins probability dial, I’ll have to disappoint you. The answer to the question depends on what you mean by “God”. If the god that you’re imagining presupposes a fundamental ontological division between humans and other creatures, then the needle surges up, red-lining the dial. But if by “god” you mean the idea that ethical statements might reflect some kind of objective reality in the universe, the needle does not know what to do, but is inclined to remain low, listening.

3. Dawkins’ long-standing and vigorously argued positions on religion are well known and in many ways they define the way in which the field of biology is seen by non-biologists, especially in the area of biology’s relationship with religion. As my book’s Preface makes abundantly clear, I used an idea taken directly from religious traditions – the potential insights offered by contemplative practice, a practice that has an important role in my life – and applied it to observation of the ecology of a forest. Mine is a markedly different attitude toward the biology-religion relationship than has been advocated by Dawkins. So I mentioned him briefly in a multi-hour interview, indicating that I did not agree with some of his positions and statements. For those who don’t want to read the book, but want to assess my approach, the reviews of the book (http://theforestunseen.com/reviews/) do a good job of outlining my basic stance towards the use of contemplative practice in the context of scientific observation and reflection.]

Itch, magnified

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My Advanced Ecology and Biodiversity class continues its investigation of our local tick populations. A few weeks ago, we collected ticks in the field and preserved some of them in alcohol. We’ve now looked through these collections using microscopes. We collected only “seed ticks,” little animals that are barely visible to the naked eye, so this close examination lets us identify the life stage and species of each individual.

For anyone who has been attacked by a swarm of seed ticks, the view down the microscope is at first a little horrifying. These agents of suffering loom up at us, unlocking a shiver of fear. Several of us unconsciously reached down to scratch our legs as we looked through the eyepieces.

After a few minutes and, paradoxically, at higher magnification, the little creatures take on a certain rotund charm. The fact that they are pickled helps a lot. We can tell larvae (the first life stage after the egg) from nymphs (the stage that comes after a larva feeds and molts) by counting legs: six for larvae and eight for nymphs. If only all biological identification were so easy.

The majority of the ticks in our collection were larvae. These two are lone star ticks, identified by the shape of the mouthparts and the number of crenelations on the rear of their body (this feature is hard to make out, especially in home-spun photos like these — taken by holding a camera up to the microscope lens…):

We also found a few dog tick larvae. Note the different shape of the mouthparts:

Nymphs were much less abundant, although we did find a few. The following is a the nymph of a lone star tick (the hindmost pair of legs is tucked in, but you can see them if you look closely).

Undoubtedly, the mouthparts are the most fascinating part of the animal. The two outer parts are the palps, used to feel around for a choice spot to drill. The inner portion is made from two knives and a barbed feeding tube. The knives, called chelicerae, open the skin. Then the tube, the hypostome, is inserted and cemented. The cement both holds the animal in place and serves as a gasket to stop leaking. The animal then spits a mixture of chemicals into the host to loosen up the blood. The ticks are fracking us for protein. Without the permission of the landowner.

Of course, when ticks feed, they may also transmit diseases such as Lyme, Rocky Mountain Spotted Fever, and Ehrlichiosis. In the case of Rocky Mountain Spotted Fever, the larvae may hatch already carrying the disease, having received it through the egg from their mother. But the other diseases are not transmitted through eggs. Instead, larvae become infected when they feed on mice and other vertebrate hosts. Larvae only feed once before turning into nymphs. So a bite from a larval tick is generally less dangerous to a human than a bite from a nymph or adult. The latter have fed on other vertebrates and are more likely to carry disease. Good to know, but little comfort when your legs are aflame with the itches of a hundred bites.

My students are currently extracting DNA from the animals to confirm our identifications and to test for diseases. I’ll keep you posted. In the meantime, remember to tick check. These diseases are a reminder that parasitism and disease are ubiquitous components of the ecology of our world.

Scratch, scratch.

Rambling into the Times

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“Finding Zen in a Patch of Nature” — The New York Times has published a beautiful profile of my work. I feel very lucky and honored to have my work discussed in this venue, especially the Science section which for years has been my go-to place for science news and great writing. Jim Gorman has done a fabulous job of situating The Forest Unseen at the junction of science, literature, and contemplative practice. Ramble also gets a mention and regular readers may recognize themes from some of the photographs. I’m looking forward to seeing the full spread in the print version tomorrow. Also in the works is an interview in the weekly Science Times podcast, available soon on the Science page.

Thank you, Ramble followers, for your ongoing support of this blog. It is a great pleasure and privilege to share my biological and literary musings with you. Our “regularly scheduled programming” will resume shortly (with more ticks, among other delights).

Parasitic ants, unwise language, and a little glimpse of Darwin

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Several weeks ago I came across a curious highway of ants. They were streaming across the leaf litter in a column about a foot wide. The column started under an oak tree, traversed the leaf litter and hiking trail, then ended abruptly about forty feet away in an otherwise unremarkable patch of fallen leaves. Ants traveling away from the tree were carrying white, ant-sized objects in their jaws. Ants moving in the opposite direction were empty-mouthed. At the destination, a few smaller ants milled about, seemingly at ease among the larger ants that I was watching.

I suspected at the time that I was witnessing a raid by a so-called slave-making ant species. My skills as an ant taxonomist are limited and I turned to my colleagues for help. Thanks to James Trager and Ann Fraser, I’ve confirmed my suspicion and been able to tentatively identify the species in question as Formica subintegra and Formica subsericea (an aside: Ant Blog is a great place to seek answers about ants). The first species, the larger one, was attacking the nest of the other and carrying away eggs and larvae. These captured youngsters will be raised in the “den of thieves” and, when they emerge as adults, the newly pupated ants will have no idea that they do not belong. Because ants take their cues from the chemical milieu in which they grow up, the stolen ants consider themselves full members of the alien colony. This trickery buys the captors a work force to maintain the nest and rear more young. In some ant species, the captors are so dependent on the captured workers that they cannot survive without them, having lost the ability to feed themselves and take care of the brood.

In the biological literature this arrangement has, for many years, been called “slave-making.” This makes me deeply uncomfortable. Using a term — slavery — from a human institution that all (or nearly all) modern human societies have agreed is morally unacceptable seems unwise. Further, the “ant slavery” term implies a biological equivalence that does not exist. There is not a single biological parallel between the details of the situations in humans and ants (ants raid other species, ant societies and nervous systems differ radically from ours, etc). By using a term derived from human society, a term that comes with considerable moral heft, we blind ourselves to the otherness of the ants. So in addition to the moral argument (which is strong enough on its own, I think), there are scientific reasons for not using the term: our preconceptions may cause us to fail to understand ant biology.

In other areas of biology, we’ve thankfully tidied up our terminology a bit. Textbooks on animal behavior were formerly strewn with terms like divorce, rape, and prostitution. These days, textbooks generally leave these loaded terms at the door, although more popular media outlets and some scientists continue the unfortunate practice. For example: Wikipedia (of course), BBC, and The Independent (note how the coverage slips so easily into discussion of what is natural for humans; Hume shudders, as explained (of course) on Wikipedia). My point is not that conflict, coercion and suffering do not occur in nature (of course they do), but that the use of human categories to describe animal behaviors can lead us into trouble. This is especially true when those categories carry with them a strong emotional, intellectual or moral charge.

Back to the ants. I was particularly excited to see this process unfold because it has a place in the history of biological ideas. Darwin was fascinated by these ants and used them in Chapter Eight of On The Origin of Species as an example of how natural selection could mold behavior (or “instinct” as he called it). He writes:

We shall, perhaps, best understand how instincts in a state of nature have become modified by selection by considering a few cases. I will select only three, namely, the instinct which leads the cuckoo to lay her eggs in other birds’ nests; the slave-making instinct of certain ants; and the cell-making power of the hive-bee: these two latter instincts have generally and justly been ranked by naturalists as the most wonderful of all known instincts.

Darwin dug up and manipulated a number of nests in England, experimenting with the ants to better understand the nature of the “slaves” and “masters” as he termed them (Darwin was not shy here or elsewhere in his writing about linguistic cross-over from human behavior). He concludes that:

…natural selection might increase and modify the [parasitic] instinct—always supposing each modification to be of use to the species—until an ant was formed as abjectly dependent on its slaves as is the Formica rufescens.

The complete account is available in the many online copies of The Origin (or in the treasured copy of this volume on your bookshelf).

In the years since Darwin, hundreds of studies have been conducted on the socially parasitic ants, many of which are summarized in a short review by Buschinger. One recent study of particular note is the discovery of retaliation by a genus of ant that is frequently attacked by parasites. The host genus is Temnothorax — tiny ants that nest inside acorns (!) and hollow twigs — and the parasite is Protomognathus americanus. Unlike the larva-robbers that I observed, Protomognathus parasitic ants invade and take over the nest of the host. Temnothorax adults are killed and their young are co-opted to work for the parasite. It appears that these attacks are so common that natural selection has produced a counter-measure: genes in some of the host workers cause them to attack the parasite, killing the developing Protomognathus pupae.

The authors regrettably use the terms “slave rebellion” and “revolt against their oppressors” to describe the behaviors that they describe. Surely a human rebellion against slavery is biologically and morally different than a gene variant causing an ant to use chemical cues to bite a pupa? My grousing about language aside, this is a remarkable study. Darwin would have loved to add this co-evolutionary tale to his chapter on the evolution of animal behavior.

From now on, I’ll be examining acorns more closely.

Rachel Carson’s legacy

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The Sunday “Perspectives” section of the Chattanooga Times Free Press is running my column about Rachel Carson, along with a column about the politics of conservation by David Yarnold, president of the National Audubon Society. The layout is beautiful — I was expecting an unadorned column, but this morning I opened the paper to find a spread with Carson framed by bird sketches.

The columns are not online, so I can’t redirect you to the paper itself. I retain copyright, so I’ve reprinted my column below.

“Rachel Carson’s legacy

This year marks the fiftieth anniversary of the publication of Rachel Caron’s Silent Spring. Carson is rightly remembered for her effects on our lives. Thanks to her, attitudes about synthetic chemicals have changed and regulatory oversight of toxins is more rigorous. Many of us now carry in our bodies fewer of the poisons that she warned about. Silent Spring is also remembered as a work of art. Her writing was both lyrical and scientifically rigorous, a rare combination. Carson unearthed, interpreted, and synthesized hundreds of arcane technical papers and government reports, then sung them straight into our hearts.

These are achievements worthy of celebration and remembrance. Yet Carson left another legacy, one that she believed was deeper than activism or literary mastery. She wrote that if she could give just one gift to every child, she would bestow “a sense of wonder so indestructible that it would last throughout life, as an unfailing antidote against the boredom and disenchantments of later years, the sterile preoccupation with things that are artificial, the alienation from the sources of our strength.”

For Carson, this sense of wonder was developed by opening our minds, emotions, and senses to the world. She implored us to look up at “the misty river of the Milky Way,” to peer at moss with a hand lens and see a world where “insects large as tigers prowl amid strangely formed, luxuriant trees,” to attend to our noses and “savor the smell of low tide,” and to hear in the dawn chorus of birds “the wild medley of voices . . . the throb of life itself.”

Carson established her reputation with books that celebrated the biological and physical marvels of the world: periwinkles, sea weeds, eels, and ocean currents. She lifted the study of natural history from the quiet, dusty parlors of the Victorian age and made it relevant for her generation, becoming, in her own words, a creator of a “new type of literature . . . representative of our own day.” In Silent Spring, she took this further and used the testimony of natural history — robins, earthworms, plankton, caterpillars, and cells under microscopes — to make her case against the imprudent use of chemicals. So although Silent Spring is remembered for bearing fruit in legislatures and regulatory offices, it was rooted in Carson’s life as a naturalist.

For Carson, the practice of natural history was a source of both delight and profound moral significance. Even at her most polemical, when delivering a speech on pollution to medical professionals as she was dying of cancer, her arguments were grounded in stories about the evolution and ecology of our world. Her speech was not focused on policy recommendations or the details of toxicology. Rather, she opens with a discussion of the origin and evolution of ecosystems, then closes with Charles Darwin. Where in today’s environmental discourse do we hear such zeal for the unfolding drama of evolution?

Carson’s references to biological context were not merely rhetorical window-dressings. The fact of our kinship with the rest of life was the foundation of her worldview; the joyous study of the particularities of the natural world was the ground from which her activism grew. In poisoning the world, she believed, we poison ourselves, for there is no separation between nature and mankind. And there can be no wise decisions about “our true relationship to our environment” without intellectual and emotional connection to the community of life. Darwin taught us that we are kin to the rest of life; Carson taught us that this kinship leads to empathy and responsibility.

So, how to celebrate, honor, and carry forward the insights of Silent Spring? Use synthetic chemicals with care and caution? Of course. Engage with the political process? Yes. But most of all, I think Rachel Carson would want us to take up “the creed I have lived by . . . a preoccupation with the wonder and the beauty of the earth.”

Is this preoccupation with the study of nature naïve or outmoded? No. Carson’s call is all the more pressing today. Biological diversity is plummeting worldwide and our climate is dangerously destabilized. Yet mere abstract knowledge of these trends is not enough. Without emotional and aesthetic connection to the natural world, we’re dislocated from any reason for action.

So our homework assignment from Carson, fifty years after Silent Spring, is to get to know a tree, to listen to a bird and to smell the beauty of soil. By giving our attention to the ecology of our homes, we’ll find Carson’s most important legacy: wonder.

David George Haskell is the author of The Forest Unseen: A Year’s Watch in Nature (Viking 2012). He is a Professor of Biology at the University of the South in Sewanee, TN.

Chattanooga Times Free Press, October 14th, 2012″

Spicebush swallowtail caterpillar

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My colleague David Johnson’s Field Investigations in Biology class found this caterpillar on one of their forays into the woods. The animal was discovered hitching a ride on a student’s boot and was brought back to campus for the admiring crowds. I kidnapped it (the caterpillar, not the boot) for a photo shoot.

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This caterpillar does a fabulous impression of an outrageously colorful snake. Note the light “reflection spots” within each “eye.” When distressed, the caterpillar will apparently inflate its head and rear up. I poked it a little, but could get no response. I did not feel like tearing at its skin like a real predator (my inner blue jay would not come to the surface), so the snake-charming will have to wait for another day.

Spicebush swallowtail caterpillars spend their first few instars (“life stages”) looking like bird droppings. This allows them to loiter in plain view and they generally sit on the upper surface of leaves. Their last instar is the snake-mimic. At this stage they roll leaves into loose cigars and hide inside the bore of the roll. Their snaky heads face outward.

The caterpillar will shortly turn into a crusty brown pupa from which the adult butterfly will emerge in the spring. Sewanee has plenty of the species’ two host-plants — spicebush and sassafras — so this species is quite abundant, but the spectacular caterpillar is surprisingly hard to find.

Migration

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As we slide down the slope behind the equinox, animals have accelerated their autumnal movements. My backyard now consistently hosts several migrant bird species each day. In the last week: rose-breasted grosbeaks, magnolia warblers, Tennessee warblers, American redstarts, gray catbirds, chestnut-sided warblers, warbling vireos, and a summer tanager. Unlike the songsters of spring, these mostly silent birds can be hard to detect. A flicker of foliage reveals their presence, then a glimpse of their plumage as they prance through the concealing twigs. Grosbeaks are an exception to this crypsis. Although they can be hard to see, their sharp tweek call, given repeatedly through the day, gives them away. The sound is just like that of a sneaker squeaking on a gym floor. Listen for it, then look up.

Last night, as I left the Biology picnic on campus, another migrant bird making a spectacular display over the old building that houses the fire station. About two hundred chimney swifts were scything the air in a tight, fast vortex. They swirled around the brick chimney that protrudes from the station’s roof. One by one, they folded their wings and dropped in. Like hot cinders carried up by the wind, these birds seemed to ignite the dead dusky air with their coordinated vitality. A little tornado of life. The swifts are on their way south to the Amazon where they’ll feast on tropical gnats all winter. I suspect that they are speeding on their way as I write: this morning’s cold rain squalls mean there will be few flying insects in Sewanee today. Time for swifts to get out of here.

Birds are not the only migrant animals making their way through our skies. This week has seen an impressive number of monarch butterflies winging across the treetops. It seems impossible that so slow and delicate a flyer could make it all the way to Mexico, but that is where they are all headed, to a few small patches of dense fir forest in the highlands. The monarchs gather there in the tens of millions to rest in the cool but unfrozen woods. Remarkably, these autumnal migrants are the grandchildren of the butterflies that left Mexico this spring. Somehow their genes guide them to precisely the right location.

One for the road: a monarch loading up on thistle biofuel earlier this week near Lake Dimmick.

Another migrant butterfly, less celebrated than the monarch, is the gulf fritillary. This species breeds all over the southeastern U. S., but overwinters only in the deep south. Unlike the fluttery monarchs, these butterflies scull their way across the air with seemingly powerful and directed wingbeats. In Florida, where adults linger all winter, huge flocks of them will sometimes stream over fields and scrubby areas. A river of bright amber.

Gulf fritillary. Photo taken earlier in the year.