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Research Paper Guidelines

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You will write a paper that analyzes a topic relating in some way to the topic of this course, in other words to trees. It must be a “conversation” as it were with the material you have read during your research. You will respond to the information you have collected and analyze it. Read it closely; come up with your own “take” on the topic. With what do you agree? With what do you disagree? Where could the argument go further? Or in another direction? I don’t want to just read a summary of what you have researched. You will take your research and use it to create your own original and debatable argument/claim.

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You may not submit a survey paper, i.e., a paper whose thesis simply claims that you will present current research on climate change and tree health, or a history of dendrology. You may, of course, choose something related to your major. However, do not recycle any other papers/projects, from any class for this paper.

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The research paper must be a formal, academic essay, following MLA style guidelines. It must be 10 full double-spaced pages with one-inch margins, using Times New Roman, 12 font. Your Works Cited does NOT count towards your 10 pages. Please do NOT include a title page.

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The paper must present both your point of view as well as another point of view. You will evaluate the other point of view respectfully either by refuting it, or by using it to bolster your own argument. Explain why the other point of view is not logical, not relevant, is outdated, etc.

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Your paper must have a list of Works Cited. You must actively use and cite a MINIMUM of NINE scholarly sources. These are from scholarly journals and/or book chapters. You will use the UE databases to access the journals. You may include texts we have read in this class as well as texts from other classes, but only IN ADDITION to the other nine sources. If you choose, to write a literary analysis or a filmic analysis, the literary work or the film do not count as one of the nine sources. As you probably realized from the annotated bibliography assignment, you might not always find a source directly related to your topic.

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All interviews count as one entry. All newspaper articles count as one entry. All artwork examples count as one entry. You are not required to use interviews, newspaper articles or artwork as a source. Your sources must include scholarly books and articles. Do not use encyclopedias except as additional to your nine other sources.

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The research paper assignment is meant to promote thoughtful scholarship, and careful, critical, and convincing writing which includes respectfully acknowledging and evaluating other points of view. You will have a debatable, original claim, which you back up convincingly throughout the paper. You will use in text citations. Do not use „I“. You are responding critically to the texts you read. The introduction should be a roadmap to the entire essay. Your claim should be clearly stated in the introduction. In addition, create a thoughtful and intriguing title that functions as a mini-claim. Actively show how you arrived at your claim. Anticipate reader pushback and strengthen your essay by successfully recognizing and addressing possible weaknesses to your claim. Integrate your sources well. Think about transitions between paragraphs.

You are to pick a topic that relates to trees. You can use some of the class materials in addition to your new research. It is wide open since I want you to find something you are interested in. It can be related to your major but does not have to be. Just make sure you are arguing something and not just presenting a survey paper.

Prairie Schooner
Prairie Schooner
Volume 88, Number 1, Spring 2014
University of Nebraska Press
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Moon Trees
— (bio)
Stute’s heels clipped my toes as he rocked back, half in and half out of the doorway to
our apartment. He was ten then. I was eighteen. I had my hand on his back, and I
could feel how sti! his small, hard muscles turned, as if he was clinching everything.
The word “um” cracked out of him, just a splinter of his little voice. Liminal moment. I
should have run. I should have le” right then. I should have grabbed my little brother
and hauled his skinny ass away, taken a train right out of Louisiana. Sometimes at
night I whisper it: I should have. I should have. Making my voice the wheels of a train.
I had enough money in tips saved that we probably could have just run.
Maybe we could have, anyway.
I didn’t need to know what he saw in there. I didn’t need to look past the
doorframe. I knew “um.” I knew that sound, that squeak. I knew it meant we were
about to cross the threshold into crazy.
It was not new to me, the world on the other side of that door.
I have known it my whole life. It has been everything.
Even the story of who I am.
When I was small, my mother would sometimes tuck me into her lap and tell me
how Stuart Roosa flew an unborn forest round and round the moon in 1971 and then
sprinkled the earth with it. Her voice was always earnest, every sentence a sacred
truth. I can tell you word for word the story of my mother finding one of those seeds
and hiding it in a locket. I can tell you how one day, when she was very lonely, she
gobbled up that seed to make me. When I was a child, I did not fall asleep to
Cinderella’s broom strokes and ballroom dancing. Instead, my mother told me of how
her fish-white belly, iridescent with life, grew heavy and cratered with my weight. I
branched out inside of her, and my fetal limbs, long and searching, pierced her brain
and le” her addled.
That is her myth. [End Page 147]
She has paranoid schizophrenia, and when she misses her medication (which
helps only a little anyway), she wears an honest-to-goodness tin foil hat. I do not
know when she stopped taking it this time. I hadn’t been counting the pills like I
should.
Stute was ever hopeful, even clinched like that in the doorway. “Momma?” he said.
He is black hair and black eyes and hope, not a bit of him matching either our mother
or me. I knew his father, and I wonder how such a kind man could have le” his baby
boy with the two of us. How, as he’d fled our mother’s madness, he hadn’t taken the
child, hadn’t clutched the baby to his chest, shielded him from what he must have
known the future held. But he did leave, taking nothing with him, disappearing
before the crib was even put together.
“Momma?” Stute said again.
It’s amazing how long you can stand by an open door and not look in. Hours, days,
years. Ten-year-old Stute growing old as we stood there, my hand on his shoulder
now, his voice tumbling around in that government-funded apartment, rolling
around in our mother’s silence. But he stepped forward and then my hand wasn’t so
much holding him as being held by his movement. He was pulling me. We were in. No
turning back.
I looked around, and the tendons holding my jaw tightened. I had no idea that
Saran Wrap came in colors, pink and blue and minty green, spring pastels. Mother
had glued every hue to every wall, and she stood shaking in the center of her
kaleidoscope, the covered windows streaming in cathedral-colored light.
I didn’t realize she was crying right away. Not until Stute was tangled around her,
hugging her and whispering the same nothings I’d whispered to him when he was a
baby, hungry and scared.
I think I said, “What?” Something useful like that.
She knotted her hands in our boy’s curls; “I can’t reach,” she said. “I just can’t do it.”
My gaze followed hers. The ceiling was empty, normal. Patched and white, it was
stained orange in places from water damage, a spider web crack pulling at the edges
near the corner. Blessedly normal.
I wondered if finding her a ladder, stealing or borrowing one from the front o!ce,
would make our lives better or worse. I wondered how she’d bought so much Saran
Wrap, so much paste, if she’d paid with the money I kept in a drawer in my room. I
shook my head as Stute rubbed her stomach, his small, gold hand tracing a moon
into her belly.
“Essie. Essie, baby,” she called to me. [End Page 148]
But I stopped listening, leaving the two of them in that glimmery Easter egg, and
walked to my room.
“Essie,” she kept saying, “Essie, Essie,” the climbing wail that was my name finally
getting lost in the crackle of the Violent Femmes. The music beat its way out of the
shell of a stereo I’d found on a curb while getting high with a boy who lived in the
dorms at lsu. When I turned it up, the speaker got tinny and rattled and the sound
never got loud enough for a neighbor to complain, never really satisfied that way, but
I turned anyway, clicking the knob all the way around. Eventually, Stute followed me
and curled himself up at the foot of my bed. I didn’t bother trying to carry him to his
own, even once his so”, baby snores mixed with the music.
She is right about Roosa. I looked him up. He was a smoke jumper and an
astronaut and was the man who visited the moon with a pack full of seeds.
My myth:
I am a normal girl. I have a father, somewhere. I have a mother I will not have to
commit. I will not have to go to the coroner’s o!ce and sign paperwork. I will not have
to apologize when she bites the paramedics. I will not know that shock therapy is the
therapy of last resort. I will not learn about the paralytic she will be given to stop her
body from convulsing, from shaking itself apart. I will not know that she will sleep
through it, may lose her memory, may become nauseous, may vomit, may hate me,
may ache, may not get any better.
I will only know the things other girls know. What is on television tonight. What is at
the movies. What dancing at prom feels like. I am normal. I am not a moon tree.
Of course, none of that is really true, either.
One of Roosa’s moon trees was planted in New Orleans, right along the River Walk. A
loblolly pine. Her trunk is rough, and when my friends climb into Cilia’s Toyota to
leave Baton Rouge behind, I always beg for a space so I can lay my hands against the
loblolly’s scratchy surface while the others prowl the Quarter. Sometimes I sit there
all night, drinking a forty out of a paper bag and wondering what it’d be like to
disappear among the New Orleans homeless, the sourness of the Gulf washing over
me, imagining myself baptized in the stink of it, holy there.
Once, a couple of years before Stute was born, my mother brought me to the
aquarium, and a”er we watched the fish and had beignets, she took [End Page 149]
me to see the loblolly. She never lowered her voice as she explained that we were
sisters, me and this tree, that I was as hard inside as her trunk, which was good, I’d
need it. I was probably about six at the time.
“It’s the bark that will save you,” she said, and I imagined that meant something
and tried to find the hardness at my center, pressing my fingers into the so” flesh of
my belly every night.
It wasn’t long a”er the plastic wrap incident that our mother started breaking apart
completely.
“Get out of my head, bitch,” she screamed one night a”er I asked what she wanted
for dinner. “Get your goddamned tendrils outta my brain.”
Stute just watched her, big black eyes blinking.
I opened a can of ravioli, wondering what it would be like to eat brand-name food,
Chef Boyardee instead of Wal-Mart’s Great Value. I was sick of her screaming, sick of
working to feed us all, sick to death of her shit. “So, noodles?” I said.
I’d overheard her singing “Spaghetti is ready, baby, spaghetti is ready” to the mirror
earlier that day and had decided to be cruel. Decided to make her think I was in fact
reading her thoughts. I’d looked in the cabinet for SpaghettiOs, found only the ravioli.
Close enough.
“Bitch!” She started sobbing.
I felt guilty then, but the truth was that it didn’t matter what I said; she believed
what she believed with or without evidence. I was a ghost to her, incorporeal, not
really there at all.
“You like ravioli.” I poured the can into a pot. “Stute, grab some bread.” He pulled
himself up o! the floor where he’d been doing homework. The Saran Wrap was now
on the carpet, too, nailed and tacked and even stapled in spots. It stuck to his thighs
as he moved. I watched her watch it shi” and pull under him, watched her hands
jump around, little nervous doves, as Stute le” her floor disheveled, parts of the
brown carpet showing through.
“Toast,” I said to him, watching her carefully.
“I know what you two are doing,” she said.
It was the first time she’d included Stute in her delusions, and I knew that he’d start
coming to Pizza Hut with me weekend mornings. He could roll silverware while I
waited tables.
“I don’t think she wants ravioli,” Stute said, the sweet of his voice like nothing I’ve
ever had.
“But we do.” [End Page 150]
“Yes, we do,” he said, grinning at the toaster, our mother’s tantrum suddenly a
million miles away.
That night I shook him awake, laid a pair of blue swim trunks across his frame, and
rubbed sleep from his cheeks. “The beast is down,” was all I said.
Stute rarely asked questions, was the sort of kid that just watched everything. A”er
dinner he’d watched our mother cut her hair in jagged strokes, and I’d watched him
growing ever older under her shadow.
“Dress,” I said.
He put on the too-large Goodwill trunks without a word, as if dressing for school or
shopping, as if, even pulling on swimwear at midnight, we were normal.
“I want to show you something.” I hoped he’d ask me what, but he didn’t.
Mother was asleep on the couch, the empty bottle that helped her settle down
nearby, as good as a teddy bear. She looked small, as if part of her body had lost itself
in the scratchy plaid pillows. Stute and I each had our own rooms, and I always hoped
her sleeping on the couch was an act of love and not paranoia, hoped she was being
generous giving us the only bedrooms and wasn’t just afraid of our rooms’ small, dark
corners.
The bottle of cheap vodka told us there was no need to tiptoe, and, anyway, silence
was a lost cause with the stick of plastic popping with each step, so we moved quickly
instead of quietly, each of us wearing nothing but used, ill-fitting bathing suits.
“Breathe deep, kiddo,” I said once we were outside, and he rewarded me with a
noisy swoosh of exhale. Car exhaust and jasmine, the smells of Baton Rouge, filled
our lungs.
“Once upon a time,” I said, pointing to the full, autumn moon. In Stute’s story, we
were both moon trees. I explained that we’d fallen to earth as something more than
seeds, best friends, angels, had become separated in the atmosphere, grown legs
instead of roots so we could always find each other.
I talked as we walked, Stute’s hand sweating in mine.
He laughed at the idea of it all. “That’s silly,” he said, the lights of passing cars
making his face less serious, more childlike. “If I’d been to the moon, I’d remember. I
have an excellent memory; Ms. Becca says so.”
“It’s just a story,” I said, sounding lame. I wondered what we looked like to the
people on the road, decided we should cut through the neighborhoods [End Page
151] where there’d be fewer cars. Mosquitoes swarmed us, and I wished I’d thought
to spray him. “You sure like school, don’t you?” I shook my head, my brother so alien
to me.
“It’s good. I’m good at it.” He’d skipped fi”h grade and was making A’s in sixth. I, on
the other hand, had dropped out about halfway through ninth grade. The notes my
teachers sent home always said I wasn’t living up to my potential, but nobody read
them except me, and it was just easier one day not to go back, not to look at their
disappointed faces, and to get high in the park instead. Now I made sure to read all of
Stute’s notes, to sign our mother’s name for him. I wondered if he’d go to lsu one day.
“You can climb a tree, right?” We were almost there.
“I’m not a baby.”
“Good.” I pulled him into the sort-of-woods that lined a nearby apartment
complex, the scraggly trees planted in neat rows alongside the buildings making it
seem more upscale than our own. “Around this way,” I whispered. We hit a wooden
fence, scrambled up a tree and then over it.
On the other side was a small swimming pool, the sort that was lit from within. A
faded blue sunflower made of cracked tiles decorated the bottom. Stute clapped, and
I imagined his toddler self, always laughing. And then his thin body was fracturing the
water’s surface, and as he rippled beneath it, I thought of crystal balls, the bright
scarves of the fortune-tellers in the Quarter, imagined I was seeing some future
version of him tumbling about in the mist of precognition. A happy kid.
To escape the mosquitoes, I joined him. The water, warm as a bath, was still cooler
than the night, and so I watched him swim, my head ducked under, holding my
breath and ignoring the sting of chlorine. I wondered what it would take for us to live
in a place like this, what it would take for Stute to swim all the time.
There was a tap on my head, and a cop stood looking down at me.
“Essie,” he said.
When your mom is a schizophrenic and you’re a truant, the local cops are rarely
strangers. Stute swam on, oblivious. “O!icer,” I said back, unable to remember his
name, embarrassed that he had mine.
“What are y’all doing here?”
I thought about saying “swimming” but had learned long ago not to be smart, that
this cop was okay, sympathetic. He’d seen our mother at her worst, had even pulled
her screeching o! of the back of the man at the gas station when she decided that he
was using the security cameras to watch her bathe, the two miles between the Circle
K and the apartment an irrelevant fact. [End Page 152]
I just shrugged.
He sat down on a nearby lawn chair, wiped the sweat o! his face. “Come on out.
Let’s talk.”
I decided to leave Stute flipping under the water. “How’d you know we were here?”
“Well, I didn’t exactly know it was you two, but a guy called, said he saw a couple of
kids in bathing suits skulking around nearby. It wasn’t hard to figure where to look.”
“I’m no kid,” I said, wondering if he’d arrest us.
“How old are you now?”
“Eighteen.”
“Yeah.” He sighed. “Get your brother. Y’all can’t exactly stay here.”
“Are we going to jail?”
He just shook his head. “Get Stuart.” He moved his arm, the motion vague. “Come
on, I ain’t got all night.”
He drove us home, sent Stute into the apartment and kept me in the car. “How
bad?”
“It’s fine. We’re fine.” I prayed he wouldn’t come inside, wouldn’t see.
He handed me a card. “Call if she gets … if you need anything. And remember, you
have a record, your brother doesn’t need one, too.” He smiled at me. “Stay the fuck
out of trouble, okay?”
“Yeah.” I had no pockets for the card, kept it tight in my hand. “Sorry about the
seats,” I said, looking at the puddles we’d le”.
The thing about the loblolly pine on the River Walk is that without the plaque, you’d
never know it was special. There really isn’t anything astonishing about the moon
trees. As a matter of fact, some of them are lost. No one bothered to keep track of
where they’d been planted, had never even made the plaques. They grew at standard
rates, were blown over by winds, were swallowed by forest fires, dropped acorns,
held tree houses, got taller, wider, died.
They looked exactly like everything else.
Our mother was beautiful—when she showered, combed her hair.
She forgot to eat, or thought meals were poisoned, or just refused, and so stayed
fashionably thin, looked lovely in a sundress, good light, made a good impression.
People like pretty. Unless she was in a full-blown break, outsiders rarely saw the
depth of her disease. At worst they thought she was odd, quirky, antisocial.
Sometimes, when the meds were just right, the rare Goldilocks cocktail [End Page
153] leaving her not too hot, not too cold, she was the most fun you could imagine,
making forts out of sheets and pillows. Covering the whole house with those forts,
just for you. Letting you be the princess with a sword, a dragon killer, and then
squealing right along with you as you chased her from fort to fort.
I think maybe it was like that sometimes. Mostly it wasn’t.
So she screams a lot, strangers seemed to say, looking at us with slit eyes, but, hey,
she wasn’t so much a bad mother as one you wouldn’t want, right? In all of our years
of crazy, no one ever checked on us, and if they had, I would have told them
everything was all right.
We were fine, normal, had no need for a plaque.
So I put the cop card away. Didn’t even bother to read his name.
A”er ravioli night, she decided everything was rotten, or poisoned, or filled with mind
control bugs. So I bought her Slim Fast shakes. The way they were sealed tight, the
strangely thick walls of the cans, seemed to comfort her. The girls at my school had
practically lived o! them, so I figured she’d be fine, get her nutrients.
“Don’t touch,” she screamed as I unloaded a bag of groceries. We didn’t have a car
and lugging Slim Fast and peanut butter and canned soup in the heat had le” me
with a headache. I needed to escape.
“You unload the fucking bags then,” I said, and she was crying again. Her blond
hair, so dirty it had begun to look brown, was matted in places. I imagined gathering
her up and running a bath, telling her to close her eyes so I could soap her hair. I knew
it would soothe her, the running water, the smell of Ivory soap, but instead I walked
out of the apartment. Found a guy I knew, stayed away until dusk.
When I finally did go home, I could hear Stute crying as I opened the door, and the
taste of bile suddenly mixed with the sweet spice of the cloves the boy’d smoked
while we fucked. “Baby?”
Stute wasn’t in the living room, but she was—just sort of wandering in the dark, the
space too small for her to do more than pace a figure eight, and I suddenly thought of
the rabid dog in To Kill a Mockingbird.
“Stute?”
I found him under my bed, hysterical and hiccupping, shaking so hard I wondered
if it hurt. I checked his golden skin for marks, turning his arms, his legs, li”ing his
shirt, pulling and tugging so I could see every bit, as if that would absolve me.
“I’m sorry, I’m sorry,” I said, too afraid to ask, and seeing blood on his [End Page
154] foot, I began to shake, too, finding his frequency, matching it. But there was no
cut, and soon I was pulling myself free of him, running to the living room, flipping on
lights.
The scissors were still in her hand, and I wondered how I could have missed them
on the way in. They glinted so. “Mother?”
“Why do you all hate me?” she said, and when she turned I could see her face was
bleeding, her arms, her hands, all bloody.
“No.”
“I can’t get you out, Essie.” she said, shrugging. “I mean, I tried.” She sounded so
tired. “But I can still feel you growing in me.”
The wounds seemed small, as if she had been nipped and nipped by a rat, and I
understood suddenly that I was a thing to be cut out, excised. That Stute had had to
watch her with those scissors, had had to put his hands up to try and stop her.
“I’m sorry,” I said moving toward her carefully, but the scissors were limp in her
hand. She had given up.
I looked at Stute in the doorway. He was small for ten, had never grown right in our
shadows.
I told him everything would be all right, told him to go borrow a neighbor’s phone.
Later the cop helped with her paperwork.
When I was little, I would imagine that Roosa was my father, that my mother’s story
had some truth to it. I searched pictures of him for similarities, wondered if my hair
was maybe a little red, if the size of my ears matched his.
There was no hidden message, though, no mysterious truths. No father there.
But I had that, that dream, that escape, that idea. I had Roosa. Stute just had me.
And Momma.
When he was born, the doctors made sure she had antipsychotics pumping
through her veins constantly, and she loved Stute so very much that she complied.
She took the pills and held the baby. But she still wasn’t good with being all there,
and so I learned quickly to cradle his neck so his heavy head would not bounce, to
test the heat of the formula on my wrist.
And he revolved around her, his little hands touching her always, opening and
closing, so that I imagined he could catch her that way, that his grasping could keep
her fluttering mind still, sane for both of us.
And when she would retreat, the copper flecks in his dark eyes would [End Page
155] fall on me, and his little hands seemed to grow around mine, rooting me there
with him.
The cop says that if she does not get better, if she does not respond to the
treatment, it is unlikely the state will give me custody of Stute.
And I wonder if that would be better.
There are hundreds of moon trees.
Hundreds.
But the thing is, even though we lost some, once upon a time everybody wanted
one.
Even the emperor of Japan adopted a moon tree.
They were that loved. [End Page 156]
Leigh Camacho Rourks
Leigh Camacho Rourks teaches at Southeastern Louisiana University, where she is the assistant
editor for Louisiana Literature. She was a finalist for the 2012 Tennessee Williams Fiction Prize, and
her work has appeared or is forthcoming in Poetry Southeast, Split Infinitive, and The Kenyon Review.
She is currently finishing her first novel.
Copyright © 2014 University of Nebraska Press
Additional Information
ISSN
1542-426X
Print ISSN
0032-6682
Pages
147-156
Launched on
MUSE
2014-04-24
Open Access
No
The Vulture Tree
Katie Fallon
River Teeth: A Journal of Nonfiction Narrative, Volume 7, Number 1, Fall
2005, pp. 113-119 (Article)
Published by Ashland University
DOI: https://doi.org/10.1353/rvt.2005.0036
For additional information about this article
https://muse.jhu.edu/article/189457
[ Access provided at 4 Jan 2021 19:58 GMT from University of Evansville ]
Katie Fallon
The Vulture Tree
To be eaten by that beak and
become part of him, to share those wings and those eyes—
What a sublime end of one’s body, what an enskyment; what a life
after death.
Robinson Jeffers, “Vulture”
The tree’s bleached branches twist like misshapen arms, skeletal and bowed
as they reach towards the cloud cover. It stands stark along Interstate 79 as
I drive past; behind it billows a green curtain of leaves and pastures. Vultures hunch in crooks of the tree’s elbows, talons wrapped around knots in
the dead wood. There isn’t an official term for a group of vultures, and flock
seems too gentle—I call them a hunch of vultures. Hunch describes them
best. They hunch together in the tree, they even seem to hunch when they
soar. The vultures scan the highway as a light rain begins to fall. One
spreads its wings. Another shivers and shakes drops from its feathers.
Perched like black gargoyles they hunch and wait for something to die.
I turn off the interstate and pull into the West Virginia Raptor Rehabilitation Center. My husband, Jesse, has already arrived; his silver car parked
between poplar trees in the gravel driveway. Earlier the center received a call
about an injured turkey vulture. It had been limping around on the ground
behind a shopping center, trying to hide amid dumpsters and piles of scrap
metal. An army of feral cats had kept their distance, but hissed and growled
when the bird dragged itself from one filthy crevice to another. Jesse rescued the bird and transported it here for treatment.
Inside the raptor center, Jesse has already begun to examine our patient.
The vulture is weak. Jesse wraps his hands around the bird’s emaciated
body; its red head droops as it tries to struggle out of his grasp. The feathers
of the vulture’s underside are matted with dried feces; it must have been on
Fallon: The Vulture Tree
113
the ground for days. We weigh the bird, shine a flashlight in its brown eyes,
and gently stretch each wing. Besides being very thin it has no obvious
injuries. We put the vulture in an icu cage, and I split the belly of a dead
rat and slide it toward the bird. It tears the rodent from me with its beak,
turns its back to us and silently strips the meat from the rat’s bones.
A vulture is primal. It lives by the deaths of other creatures, but it’s not a
predator. A hawk, for example, hunts—stalks, stoops, and squeezes the life
from its prey, rips through bodies with razor talons. A turkey vulture waits.
It isn’t a murderer, and it doesn’t kill, but it’s impossible not to think about
death with a vulture nearby. Through the steel cage bars, I watch the
starved bird devour its meal, skinning meat and sinew from wet bones. It
turns the rat almost inside out, holds a corner of pelt under a toenail and
skillfully cleans the hide. The end of this bird’s beak is curved like a crochet
hook, a delicate tool for knitting through organs, separating muscle from
bone, from skin. The vulture is an intricate and meticulous artist. In a few
minutes the rat is empty. Its skin folds like baggy pants in a loose pile
around its large thigh bones. The bird seems satisfied and drags what remains of the rat to a back corner of the cage to save for later. It looks over its
hunched shoulder at me, cautiously turns, and steps onto a rope-wrapped
perch.
We don’t treat many turkey vultures at the raptor center. I would like to
believe that their intelligence allows them to avoid moving cars and humans; it seems more likely though that people have greater respect and pity
for injured hawks and eagles. Eagles are symbols of nations; we see them as
majestic birds to be proud of, and we put their likeness on currency and
leather jackets. Vultures have become greedy, sneaky undertakers. I think
injured vultures might be left to die.
A few weeks ago Jesse and I stood on an overlook platform at Coopers
Rock State Forest, admiring sailing turkey vultures. The overlook is a rocky
outcrop that provides a panoramic view of the Cheat River far below and
the wooded mountain that rises from its banks across the valley. The vultures soared almost level with the outcrop, each elegant flight feather discernible, their small brown eyes apparent in their featherless red heads.
They looked like black kites floating on the updrafts, tugged by invisible
strings, swaying in circles before us, gently rocking now and then with the
tips of their flight feathers spread like fingers.
“I wish I was a big bird,” I told Jesse.
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river teeth . fall 2005 . vol. 7 no. 1
I leaned out, elbows on the wooden railing, and imagined riding the
wind. The overlook was crowded that day; children dropped quarters into
viewing machines, and a fluffy dog yapped at us from across the outcrop.
Our dog, Billy Bones, disappointed to be stationary so long, rested his chin
on the toe of my boot. When the wooden railing vibrated under my arms I
looked around. A few feet from me a teenager was kicking one of the posts,
laughing with his friend. “I wonder,” the kicker chuckled, “if I’m too close
or too far to hit those buzzards.”
His friend lifted an imaginary rifle, pointed it at my vultures, squinted
one eye, and squeezed the trigger. “Pop,” he said. “Pop, pop.”
Besides the vulture’s less-than-heroic reputation, part of our disgust with
them might have to do with their abundance; scientists even suggest that
their numbers are increasing. An article in a recent issue of The Journal of
Raptor Research addresses this “vulture phenomenon,” focusing on a current situation in Florida.1 There the human population is growing, and
with it, the number of radio and communication towers. Apparently these
hundred-foot-tall towers have become favorite roosting spots for vultures.
According to the article, “Defecations by roosting vultures interfere with
the operation of expensive equipment and create unsafe and unpleasant
conditions for workers.” Perhaps more to the point, “Businesses and
homeowners adjacent to a vulture roost site are adversely affected by vulture
droppings and the unpleasant odor that results.”2
The authors of the article, scientists who work for the usda Wildlife
Services in Florida, have come up with a solution to this “problem”: hang
vulture carcasses around the towers. Researchers report that most vultures
circle the decorated towers but do not land. The ones who do land “peer”
at the carcass for a few moments, then fly away. The article suggests the use
of decoys since actual dead vultures might prove “distasteful” to the public.3
The vulture population boom in the eastern United States may be attributed in part to our expanding tangle of interstate highways. Concrete
bands stretch up and down the East Coast like vulture buffet tables brimming with roadkill; they follow the trail of dead bodies left in the wake of
fast cars and eighteen-wheelers. The roads serve up more groundhogs, possums, and raccoons than humans want to bother clearing away, and vultures are more efficient interstate cleaners than the department of highways. Of course when strips of forest are bulldozed to build these highways
Fallon: The Vulture Tree
115
radio towers become vulture trees, replacing gnarled oaks and dying poplars. Who can blame vultures for roosting on them?
I don’t think the unpleasantness of vulture droppings has much to do
with the situation in Florida. People just don’t like to see the hunching
birds waiting in the steel trees. Vultures remind us of our own mortality
and that life will continue after we die. They show us that something undiscriminating is waiting, maybe even hoping for that moment.
I agree with poet Robinson Jeffers: when I’m finished with my body, I want
it to be eaten by a vulture. Part of me would go on living beneath its iridescent black feathers, strengthening its powerful wing beats. Soaring with the
vulture I would help it sail on updrafts, look down on treetops. To be
pumped full of chemicals and sealed inside a box seems like a waste. I don’t
want to rot slowly underground; I want to feed the sky. I want to be set free,
turned loose, my bond to the ground finally broken. I want to be useful, to
be reused.
The Parsis, an Indian religious community, also see the value in recycling their dead. Near Mumbai their Towers of Silence loom in the center
of a fifty-seven-acre preserve. They lay the bodies of their dead on top of the
tall, cylindrical, stone towers for local vultures to devour. To the Parsis a
body buried, burned, or drowned desecrates the earth, fire, or water. They
offer their dead to the sky as an act of charity. When the vultures finish, the
human bones and remnants are put into a pit where sunlight eventually
turns them to dust, and the wind sweeps the dust into the sky.
In the United States leaving my body on top of a tower would be criminal. My loved ones would certainly go to jail for honoring my wishes. In
India though the Parsis have a different problem. While they have no shortage of bodies to place on the Towers of Silence and no laws to stop them,
the vultures that eat their dead are disappearing. Raptor biologists say that
in the last few years ninety-five percent of Oriental white-backed vultures
in India have died out.4
An article in the February 12, 2004 issue of Nature claims that a veterinary pharmaceutical called diclofenac, used to treat livestock, is responsible for this vulture decline.5 Cattle are sacred to the majority of the
Hindu population, and when the animals die their hides are usually taken,
but the corpses are left for vultures. The birds eat the cows, ingest the drug,
then die of kidney failure.
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river teeth . fall 2005 . vol. 7 no. 1
In addition to Oriental white-backed vultures, the fate of long-billed
and slender-billed vultures appears dismal as well. All three Asian species
are listed as critically endangered by BirdLife International. Rick Watson of
The Peregrine Fund writes that “The time available to take remedial action
cannot be accurately predicted, but may now be very short—perhaps a
matter of months” (emphasis added). Watson suggests that captive breeding
flocks must be established and the use of veterinary diclofenac banned if
these Indian vultures are to be saved from extinction.6
Currently cow carcasses in India are piling up. Without the vultures
packs of feral dogs and swarms of rats could descend on the dead cattle,
potentially bringing rabies and other diseases. A few dozen vultures can
strip a cow carcass clean in a matter of minutes. Now the bodies stink for
weeks. Besides disposing of the bodies vultures can actually consume some
zoonotic diseases like anthrax and botulism toxin without adverse effects to
their health, reducing the chance of the diseases spreading to humans. The
ecology, and perhaps the public health, of one of the most populous nations in the world is being thrown off balance, all because of the absence of
vultures.
For six weeks we fed and cared for the turkey vulture at the raptor center. Its
strength returned quickly, and after just a few days in the icu we moved it
outdoors. Its huge wings spanned the width of a flight cage, and when the
bird flew its length the tips brushed its sides. It was a voracious eater; when
it finished its daily rat, it would eye the rat of the red-tailed hawk in the
next cage.
On an overcast morning we decide it is time to set our vulture free. Jesse
enters the flight cage armed with welding gloves and a large towel; the vulture hisses and spreads its wings when he approaches, an intimidation tactic. Jesse throws the towel over the bird’s head and grabs its legs. In a flurry
the vulture is wrapped up and cradled in Jesse’s arms.
“He’s strong,” Jesse says. The towel slips off the bird’s head, and it turns
its frantic eyes to Jesse’s face. In a desperate lunge the vulture snaps its beak
at him, catching Jesse on the side of his neck. He curses and gets the towel
over the bird’s head. “How bad?” he asks. I run for the peroxide.
The wound is tiny, a slit the size of a paper cut just below his jaw line. I
dab the blood with a soaked cotton ball and Jesse winces. White bubbles
foam along the cut. The bird is calm under the towel.
Fallon: The Vulture Tree
117
As we walk up the hill to the hayfield I am silently jealous. The vulture
has tasted Jesse’s blood, knows him in some intimate, vampiric way. This is
strange I realize. But that little piece of Jesse will go with the vulture, and all
the pieces of me will stay on the ground.
We break through the trees along the edge of the field and trudge to the
middle. It is drizzling and a slight breeze tugs our hair. “Ready?” asks Jesse.
I nod. He pulls the towel and lets it fall to the grass. The vulture swivels its
head from side to side, squirming in Jesse’s arms.
“Good luck,” he says, and gently tosses the bird skyward. It flaps twice
but does not rise.
“Come on, get up,” I whisper. A gust of wind sweeps across the field.
The vulture tilts its tail, spreads its wings and lifts up, up over the tree line
and keeps going. We lose sight of the bird after only a few seconds. Our
vulture is free. I hope we meet again someday.
On our way home from the raptor center we pass by the vulture tree.
The drizzle has stopped, and the sun forces its way through the drifting
clouds. The tree reaches skyward in a gesture of celebration and thanksgiving. A single turkey vulture perches on a twisted branch, its wings stretched
wide. For a moment it resembles a cormorant or a giant crow, but its hunch
gives it away. The bird shimmers in the sunlight, shiny wings almost
purple. It cocks its red head slightly and examines the road. Looks into my
car, I imagine.
I think of towers—towers in Mumbai and towers in Florida, of spiritual
desperation and “expensive equipment,” of how easily some of us can imagine killing “those buzzards.” As if in response the vulture in the tree shrugs
its hunching shoulders, folds its wings over its black back and wags its tail
feathers. It digs its beak under a huge wing a moment, ruffles, defecates,
then launches. Three long flaps lift it above us, over the cars; its dark
shadow sliding across the valley, a black omnipresent V swaying on the
horizon.
notes
1. Michael L. Avery, et al., “Dispersing Vulture Roosts on Communication
Towers,” The Journal of Raptor Research 36.1 (2002): 45.
2. Avery, 46.
3. Avery, 50.
118
river teeth . fall 2005 . vol. 7 no. 1
4. J. Lindsay Oaks, et al., “Diclofenac residues as the cause of vulture population decline in Pakistan,” Nature 427 (2004): 630.
5. Oaks, 630.
6. Rick Watson, “Veterinary Use of the Drug Diclofenac Found to Cause the
Collapse of Vulture Populations in South Asia,” The Peregrine Fund, 28 Jan. 2004
http://www.peregrinefund.org/archived_conserve.asp?mode=view&ConserveID=
82&category=Asian%20Vulture%20Crisis&conserveid1=73 (accessed 30 Jan. 2004).
Fallon: The Vulture Tree
119
This page has been archived and is no longer updated
EVOLUTIONARY GENETICS | Lead Editor: Bob Sheehy, Norman Johnson
Reading a Phylogenetic Tree: The Meaning of Monophyletic
Groups
By: David Baum, Ph.D. (Dept. of Botany, University of Wisconsin, 430 Lincoln Ave., Madison,
WI) © 2008 Nature Education
Citation: Baum, D. (2008) Reading a Phylogenetic Tree: The Meaning of
Monophyletic Groups. Nature Education 1(1):190
Phylogenies are a fundamental tool for organizing our knowledge of the biological diversity we observe on our planet. But
how exactly do we understand and use these devices?
Aa
Aa
Aa
A phylogenetic tree, also known as a phylogeny, is a diagram that depicts the lines of evolutionary descent of different species, organisms, or genes from a common ancestor. Phylogenies are
useful for organizing knowledge of biological diversity, for structuring classifications, and for providing insight into events that occurred during evolution. Furthermore, because these trees show
descent from a common ancestor, and because much of the strongest evidence for evolution comes in the form of common ancestry, one must understand phylogenies in order to fully appreciate
the overwhelming evidence supporting the theory of evolution.
Tree diagrams have been used in evolutionary biology since the time of Charles Darwin. Therefore, one might assume that, by now, most scientists would be exceedingly comfortable with “tree
thinking”–reading and interpreting phylogenies. However, it turns out that the tree model of evolution is somewhat counterintuitive and easily misunderstood. This may be the reason why biologists
have only in the last few decades come to develop a rigorous understanding of phylogenetic trees. This understanding allows present-day researchers to use phylogenies to visualize evolution,
organize their knowledge of biodiversity, and structure and guide ongoing evolutionary research.
But what exactly is a phylogeny? Moreover, how should one read and interpret one of these diagrams? In an attempt to answer such questions, the following sections present a brief introduction
to tree thinking. A more complete view of this subject can be developed by learning about how traits evolve along trees, how trees are reconstructed, and how trees are used to study various
aspects of evolution.
What an Evolutionary Tree Represents
To better understand what a phylogeny represents, start by imagining one generation of butterflies of a particular species living the same area and producing
offspring. If you focus on four individual butterflies in both the parental and offspring generations, the resulting pedigree may appear like the one in Figure 1B.
Now, expand your image to encompass all the butterflies of this species in a particular meadow over several generations. A pedigree for this population might look
something like the one in Figure 1C. Note that each individual in the figure has two parents, but each gives rise to a variable number of offspring in the next
generation.
Next, imagine taking your pedigree and getting rid of the organisms, thus keeping only the descent relationships, which are the glue that holds the population
together (Figure 1D inset box). Then zoom out even farther to include many more individuals (say, from multiple meadows in the same region) and more
generations. For example, the whole of Figure 1D is derived from a similar diagram as the inset box, but it now includes more individuals and many generations. As
you can see, if one were to try to represent a typical population of several thousand individuals that persists for hundreds or thousands of generations, all one
would see would be a fuzzy line.
Individual populations may be fairly isolated for some period of time. However, on an evolutionary timescale, migration will occur among the discrete populations
that make up a typical species. This gene flow between populations has the effect of “braiding” the population lineages into a single species lineage, which might
be thought of as resembling Figure 1E.
Moreover, during evolution, lineages often split. This occurs when populations or groups of populations become genetically isolated from one another. Lineages
most commonly split because of the migration of a few individuals to a new, isolated region (e.g., an island). This is sometimes called a founder event. Alternatively,
a formerly contiguous range can be broken up by geological or climatic events (e.g., the creation of mountains, rivers, or patches of inhospitable terrain). This
phenomenon is called vicariance. No matter whether populations split due to founder events or vicariance, if the isolated populations remain separate, they will
start evolving differences from one another (Figure 1F). After all, a mutation that arises in one population will have no way to get to the other population. Thus,
even a mutation that would be selectively favored in both populations will become fixed in only one of the groups.
Figure 1
As a consequence of this genetic isolation, the lineages will evolve separately, becoming more and more different over time. If they remain apart for long periods,
enough physiological and behavioral differences may evolve to result in reproductive isolation, such that it will be impossible for individuals from the two lineages to
Figure Detail
reproduce even in the case that they do come back into contact. Because of this, it is a useful simplification to assume that once lineages diverge, the two sets of
descendants will remain distinct.
Figure 2B shows what we might see if we followed the fate of a single ancestral lineage (Figure 2A) long enough that it
gave rise to four descendant lineages (species). This example includes three lineages that were established but became
extinct before the end of the observation period. This diagram is an example of a simple phylogenetic tree.
In most cases, researchers draw phylogenetic trees in such a way as to record only those events that are relevant to a
set of living taxa. Most commonly, these taxa are species. For example, Figure 2C shows the basic tree we could draw to
represent the history of the four “tip” species, A through D. This tree shows that species A and B share a more recent
common ancestor with each other than with either species C or species D. Likewise, species C and D share a more
recent common ancestor with each other than with either species A or species B. This example illustrates the fact that a
phylogeny is, at its most basic level, a history of descent from common ancestry.
Phylogenetic trees are fractal in the sense that the same pattern is found whether we consider recently diverged lineages
or deep splits in the tree of life. Indeed, the most basic postulate of evolutionary theory is that the same general
phenomenon of descent from common ancestry applies to both the most diverse branches of the tree of life and the most
Figure 2: Branching pattern of four species.
Genetic connections of populations can be depicted by a
phylogenetic tree.
© 2008 Nature Education All rights reserved.
similar. As a result, the tree structure is extremely helpful in tracking biological diversity at all levels.
Figure Detail
The Lexicon of Phylogenetic Inference
Most phylogenetic trees are rooted, meaning that one branch (which is usually unlabeled) corresponds to the common
ancestor of all the species included in the tree. Note, however, that a tree can be drawn in any orientation. Figure 3, for
example, shows a simple rooted tree with the root at the bottom and the tips at the top.
The labels at the “tips” of a phylogeny can correspond to individual organisms, to species, or to sets of species, as long
as each tip makes up a separate branch on the tree of life. In fact, in certain contexts, the tips can even correspond to
Figure 3: Phylogenetic terminology.
individual genes. In any case, some general terms for the items represented by these tips include “terminals,” “terminal
taxa,” or “taxa”; in more mathematical circles, they may also be called “leaves.” As opposed to tips, the branching points
A root is the ancestral population from which all the other species
within a tree, which correspond to inferred speciation events, are called nodes. Each node represents the last common
originate. A node represents a branching point from the ancestral
ancestor of the two lineages descended from that node. Internal branches or internodes connect two nodes, whereas
population. Terminals occur at the topmost part of each branch,
external branches connect a tip and a node.
and they are labeled by the taxa of the population represented by
that branch.
© 2008 Nature Education All rights reserved.
A clade is a piece of a phylogeny that includes an ancestral lineage and all the descendants of that ancestor. This group
of organisms has the property of monophyly (from the Greek for “single clan”), so it may also be referred to as a
monophyletic group. A clade or monophyletic group is easy to identify visually: it is simply a piece of a larger tree that
can be cut away from the root with a single cut (Figure 4a). Accordingly, if a tree needs to be cut in two places to extract
a given set of taxa, then those taxa are non-monophyletic (Figure 4b).
Clades are natural chunks of trees because there is a portion of history (specifically, the internal branch that attaches the
Figure 4: A monophyletic group, sometimes called a
clade to the rest of the tree) that is common to all members of the clade and to no other tips. As a result, statements of
clade, includes an ancestral taxon and all of its
common ancestry that apply to a clade always apply to all tips within the clade. For instance, if you are told that
mammals share a more recent common ancestor with lizards than with sharks, and if “mammals” refers to a clade, then
descendants.
you can deduce that all mammalian species share a more recent common ancestor with lizards than with sharks.
A monophyletic group can be separated from the root with a
single cut, whereas a non-monophyletic group needs two or more
This is not true of non-monophyletic groups, as can be illustrated by reference to the traditional (but misleading) concept
of “reptiles,” which included lizards, snakes, crocodiles, and turtles, but not birds. Because “reptiles” (in this sense) does
cuts.
© 2008 Nature Education All rights reserved.
not refer to a monophyletic group, it is difficult to make general statements about the organisms in this group.
Figure Detail
Furthermore, researchers now know that crocodiles share a more recent common ancestor with birds than with lizards,
snakes, or turtles. Thus, current concepts of “Reptilia” generally include birds as members of this clade. Indeed, it is
because of such problems with non-monophyletic groups that modern systems of classification strive to give formal
names only to monophyletic groups.
How to Read an Evolutionary Tree
Unless indicated otherwise, a phylogenetic tree only depicts the branching history of common ancestry. The pattern of
branching (i.e., the topology) is what matters here. Branch lengths are irrelevant–they are simply drawn in whatever way
makes the tree look most tidy. Thus, the three trees shown in Figure 5 all contain the same information.
Similarly, tree diagrams can depict the same information yet be oriented in different ways. The three trees in Figure 6, for
example, have the same topology and thus the same evolutionary implications. In each case, the first divergence event
separated the lineage that gave rise to tip A from the lineage that gave rise to tips B, C, and D. The latter lineage then
Figure 5: Patterns of evolutionary descent.
The information provided by patterns of evolutionary descent is
split into two lineages, one of which developed into tip B, and the other which gave rise to tips C and D. What this means
the same regardless of the lengths of branches.
is that C and D share a more recent common ancestor with each other than either shares with A or B. Tips C and D are
© 2008 Nature Education All rights reserved.
therefore more closely related to each other than either is to tip A or tip B. The diagram also shows that tips B, C, and D
all share a more recent common ancestor with each other than they do with tip A. Because tip B is an equal distance (in
terms of branch arrangement) from both C and D, we could say that B is equally related to C and D. Likewise, B, C, and D are all equally related to A.
It might seem confusing that such different-looking trees can contain the same information. Here, it might be helpful to
remember that the lines of a tree represent evolutionary lineages — and evolutionary lineages do not have any true
position or shape. It is therefore equally valid to draw the branch leading to tip A as being on either the right or the left
side of the split, as shown in Figure 7. Similarly, it doesn’t matter whether branches are drawn as straight diagonal lines,
are kinked to make a rectangular tree, or are curved to make a circular tree. Think of lineages as flexible pipe cleaners
rather than rigid rods; similarly, picture nodes as universal joints that can swivel rather than fixed welds. Using this sort of
Figure 6: Types of phylogenetic trees.
imagery, it becomes easier to see that the three trees in Figure 7, for example, are equivalent. The basic rule is that if
These trees depict equivalent relationships, despite having
you can change one tree into another tree simply by twisting, rotating, or bending branches, without having to cut and
different appearances.
reattach branches, then the two trees have the same topology and therefore depict the same evolutionary history.
© 2008 Nature Education All rights reserved.
It might seem confusing that such different-looking trees can contain the same information. Here, it might be helpful to
remember that the lines of a tree represent evolutionary lineages–and evolutionary lineages do not have any true
position or shape. It is therefore equally valid to draw the branch leading to tip A as being on either the right or the left
side of the split, as shown in Figure 7. Similarly, it doesn’t matter whether branches are drawn as straight diagonal lines,
are kinked to make a rectangular tree, or are curved to make a circular tree. Think of lineages as flexible pipe cleaners
rather than rigid rods; similarly, picture nodes as universal joints that can swivel rather than fixed welds. Using this sort of
Figure 6: Types of phylogenetic trees.
imagery, it becomes easier to see that the three trees in Figure 7, for example, are equivalent. The basic rule is that if
These trees depict equivalent relationships despite being different
you can change one tree into another tree simply by twisting, rotating, or bending branches, without having to cut and
in
reattach branches, then the two trees have the same topology and therefore depict the same evolutionary history.
© 2008 Nature Education All rights reserved.
Finally, it’s important to note that in some instances, rectangular phylogenetic trees are drawn so that branch lengths are
meaningful. These trees are often called phylograms, and they generally depict either the amount of evolution occurring
in a particular gene sequence or the estimated duration of branches. Usually, the context of such trees makes it clear
that the branch lengths have meaning. However, when this is not the case, it is important to avoid reading in any
temporal information that is not shown. For example, Figure 8 may appear to suggest that the node marking the last split
Figure 7: Relationships on a phylogenetic tree can be
leading to tips A and B (marked x) occurred after the node separating tip C from tips D and E (marked y). However, this
depicted in multiple ways.
should not be read into the tree; in reality, node x could have occurred either before or after node y.
These trees depict equivalent relationships despite the fact that
certain internal branches have been rotated so that the order of
the tip labels is different.
© 2008 Nature Education All rights reserved.
The Importance of Phylogenetic Trees
Given the increasing use of phylogenies across the biological sciences, it is now essential that biology students learn what tree diagrams do (and do not) communicate. Developing “tree thinking”
skills also has other benefits. Most importantly, trees provide an efficient structure for organizing knowledge of biodiversity and allow one to develop an accurate, nonprogressive conception of the
totality of evolutionary history. It is therefore important for all aspiring biologists to develop the skills and knowledge needed to understand phylogenetic trees and their place in modern evolutionary
theory.
Figure 8: Trees contain information on the relative timing
of nodes only when the nodes are on the same path from
the root (i.e., when one node is a descendant of another).
In this tree, nodes x and y are not on the same path, so we
cannot tell whether the ancestral organisms in node x lived
before or after those in node y.
© 2008 Nature Education All rights reserved.
Summary
Avise, J. C. Evolutionary Pathways in Nature: A Phylogenetic Approach (Cambridge University Press, Cambridge, UK, 2006)
Baum, D. A., DeWitt Smith, S., & Donovan, S. S. The tree thinking challenge. Science 310, 979–980 (2005)
Baum, D. A., & Offner, S. Phylogenies and tree thinking. American Biology Teacher 70, 222–229 (2008)
Dawkins, R. The Ancestor’s Tale: A Pilgrimage to the Dawn of Life (Houghton Mifflin, New York, 2004)
O’Hara, R. J. Homage to Clio: Toward an historical philosophy for evolutionary biology. Systematic Zoology 37, 142–155 (1988)
O’Hara, R. J. Population thinking and tree thinking in systematics. Zoologica Scripta 26, 323–329 (1997)
Maddison, W. P., & Maddison, D. R. MacClade: Analysis of Phylogeny and Character Evolution (Sinauer Associates, Sunderland, MA, 1992)
Tree Thinking Group. Tree Thinking Group homepage, (2004)
Outline | Keywords | Add Content to Group
Explore This Subject
GENOME EVOLUTION
Origins of New Genes and Pseudogenes
MACROEVOLUTION
The Molecular Clock and Estimating
Species Divergence
MICROEVOLUTION
Evolutionary Adaptation in the Human
Lineage
PHYLOGENY
Genetic Mutation
Reading a Phylogenetic Tree: The
Meaning of Monophyletic Groups
Natural Selection: Uncovering
Mechanisms of Evolutionary Adaptation
to Infectious Disease
Trait Evolution on a Phylogenetic Tree:
Relatedness, Similarity, and the Myth of
Evolutionary Advancement
Negative Selection
Neutral Theory: The Null Hypothesis of
Molecular Evolution
Sexual Reproduction and the Evolution
of Sex
SPECIATION
Haldane’s Rule: the Heterogametic Sex
Hybrid Incompatibility and Speciation
Hybridization and Gene Flow
Why Should We Care about Species?
Cartography of Tree Space
Satyan L. Devadoss, Owen Schuh
Leonardo, Volume 52, Number 3, 2019, pp. 279-283 (Article)
Published by The MIT Press
For additional information about this article
https://muse.jhu.edu/article/728402
[ Access provided at 4 Jan 2021 20:05 GMT from University of Evansville ]
G e n e r a l
N o t e
Cartography of Tree Space
ABSTRACT
S at ya n L . D e v ad o ss a n d O w e n S c h u h
How can vibrant, contemporary art be produced that deals with vibrant,
contemporary mathematics? To address this question, a collaboration
began between an artist (Schuh) and a mathematician (Devadoss),
revolving around recent problems in phylogenetics and the space of
evolutionary trees. The result was twofold: First, a triptych of paintings
was created, using acrylic, graphite, watercolor and metal leaf, that
focused on different navigations within this tree space. Second, a novel
set of open mathematics problems was discovered solely as a result of
this investigation.
In our Enlightenment world, the work of the mathematician
and the visual artist are usually not only viewed as incompatible but also held in tension. Mathematics is attributed to
Platonic conceptions, addressed only through the mind, focusing on abstract ideas and theoretical structures. The visual
artist, on the other hand, is assumed to be relegated to works
of the hands, dealing with the concrete and the tangible. Bertrand Russell, a preeminent philosopher and mathematician
of the 20th century, exemplified this attitude when he wrote:
Remote from human passions, remote even from the pitiful
facts of nature, the generations have gradually created an
ordered cosmos, where pure thought can dwell as in its natural home, and where one, at least, of our nobler impulses
can escape from the dreary exile of the actual world [1].
Here, the “ordered cosmos” is mathematics, which can escape the “dreary exile” of physical reality, the reality artists
inhabit. Today, a century after these words were penned, Russell’s viewpoint not only lingers but continues to define much
of our worldview: Ideas based on equations and symbols hold
a greater sense of power than notions from the visual realm.
The rise of careers and funding opportunities in the STEM
fields only highlights this.
Satyan L. Devadoss (educator), University of San Diego, San Diego, CA, U.S.A.
Email: devadoss@sandiego.edu.
Owen Schuh (artist), Art 3 Gallery, Brooklyn, NY, U.S.A.
Email: owen@owenschuh.com.
See www.mitpressjournals.org/toc/leon/52/3 for supplemental files associated
with this issue.
©2019 ISAST   doi:10.1162/LEON_a_01475
There has been considerable effort over the past few decades for serious engagement between the two fields [2].
Credit should be given to the journal Experimental Mathematics, which started to bring these domains together in
1992. Most notably, the collaboration by Anderson et al. has
helped to define the role of drawing as a common language
between mathematics and art; these authors posit the source
of mathematical creativity to be the (usually inner) dialogue
between the “Thinker” and the “Drawer”: “The Thinker
exists in the world of linear logical thinking. The Drawer
operates in the world of the imagination and of inverse
vision” [3].
It is in fact the tension between the two modes of knowledge that pushes them into new territory. Much fertile
ground is still unexplored, however.
Players
A collaboration began between an artist (Schuh) and a
mathematician (Devadoss), engaging in current research
mathematics through the eyes of a contemporary visual artist. To succeed, this partnership needed to be complete, with
the mathematician involved in the drawings and the artist
involved in the mathematics. Satyan Devadoss (formerly of
Williams College) is the Fletcher Jones Professor of Mathematics at the University of San Diego, where much of his
work revolves around discrete arrangements and their underlying geometry. Owen Schuh is a visual artist currently
based in Philadelphia (formerly in San Francisco) who strives
to demonstrate the tension between physical medium and
logical and algorithmic structures.
This joint venture took place during an 18-month timeframe, from September 2013 to February 2015, overlapping
mostly with the time when Devadoss was on sabbatical leave
as visiting faculty at Stanford University. Roughly the first six
months were spent in understanding the goals of the project and choosing a point of collaboration. Devadoss assisted
Schuh in identifying and understanding the relevant material. The second six months were spent at coffee shops and
studios in the Bay Area, where both mathematics and visual
LEONARDO, Vol. 52, No. 3, pp. 279–283, 2019 279
sketches would be dissected and scrutinized. A typical meeting involved the artist presenting drawings and visual analyses, as well as asking any questions that might come up in the
process. A dialogue then ensued with on-the-spot sketches
and questions flowing in both directions, with subsequent
“homework” for both parties.
The final months focused on crafting the final details and
formulating a unifying vision to the project, resulting in a
triptych of paintings. The emphasis of each of these final
renderings was arrived at through dialogue, although the
particular visual attributes and layout were the work of the
artist, with Devadoss assisting in some of the final drawing
of the triptych. The resulting undertaken project revolved
around certain unsolved problems dealing with shapes and
structures motivated by phylogenetics. This work culminated
in an exhibit [4] at Satellite Berlin—Art in Collaboration, 14
March–25 April 2015.
Mathematics
A classical problem in computational biology is to reconstruct an evolutionary “tree of life” from the genetic information of a set of species. The tree here is an abstract one
(sometimes called a phylogenetic tree), with a root at the bottom, branching out into leaves. Each leaf is identified with a
Fig. 1. Twenty-five tree-types with four species. (© Satyan L. Devadoss)
Fig. 2. Growing and shrinking edges in tree space. (© Satyan L. Devadoss)
280 Devadoss and Schuh, Cartography of Tree Space
different species in our set. As an example, given a set of four
species {1,2,3,4}, Fig. 1 shows the 25 distinct ways these species
can be related in a phylogenetic tree structure. The top row
of trees has a single internal edge, with the other rows having
two internal edges.
But instead of looking at this set of trees, we wish to form a
space of trees. Just as the set of numbers can be given a shape,
namely in the form of the number line, the set of trees can
be arranged to form a space: Trees are related by collapsing
and growing the internal edges. Indeed, each internal edge
of a tree is given a length, viewed as the measurement of
evolutionary time.
Figure 2 shows a part of this construction: Notice that by
collapsing the top internal edge of tree A, we obtain tree Y.
One can then grow an internal edge in two possible ways,
resulting in trees B and C on the right. Similarly, collapsing
the bottom internal edge of tree A results in tree X, which is
related to trees D and E. This figure only shows how seven
trees (A, B, C, D, E, X, Y) are related; the full tree space, which
relates all 25 distinct trees, is shown in Fig. 3, resulting in
the famous Peterson graph [5]. The 15 edges match up with
rooted trees with four leaves and two internal edges (such as
A, B, C, D, E above), and its 10 vertices match up with rooted
trees with four leaves and one internal edge (such as X and
Fig. 3. Vertices and edges of tree space T(4). (© Satyan L. Devadoss)
Y above). We denote T(4) as the entire space of rooted trees
with 4 leaves.
These tree spaces T(n) exist for any value of n species, and
have appeared in mathematics since the 1960s, under the
theory of operads [6]. But recently, due to a surging growth
in computational biology, tree spaces have resurfaced. This
was spearheaded by a seminal work at the start of the 21st
century by Billera, Holmes and Vogtmann [7], who studied
the geometry of these spaces. However, understanding and
visualizing these spaces is not only far from easy, but in many
instances, quite novel.
Fig. 4. Combinatorics and relationships between tree-types in T(5).
(© Satyan L. Devadoss)
Five Species
Unlike the case above, the complications increase severalfold when considering T(5), the space of tree for five species.
This space is made of 105 triangles, 105 edges and 25 vertices,
where each triangle corresponds to a tree with three internal edges. The combinatorial structure of these trees is given
in Fig. 4: The top row shows trees with one internal edge,
which come in three different types (K–M), with 10, 10 and
5 distinct trees of each type. These form the vertices of T(5).
Rows 2 and 3 show trees with two and three internal edges,
respectively, coming in five (A–E) and three (X–Z) different types, forming the edges and triangles of T(5). The connections between each of the rows shows adjacencies of the
objects. The curious reader is encouraged to see Devadoss,
Huang and Spadacene [8] for further details.
Visualizing only the vertices and edges results in Fig.
5a (drawn using Illustrator), where the five types of edges
and the three types of vertices are color coded to match
the scheme from Fig. 4. The rich, highly symmetric structure here is akin to the structures presented by Coxeter and
Shephard [9]. Indeed, this deeper connection is not coincidental, as tree spaces T(n) have close ties with objects called
Coxeter complexes [10]. Note that including the 105 triangles
of T(5) in this diagram is not possible in two or three dimensions—that is, although this space is made of up flat triangular pieces, it needs higher dimensions to be accurately
visualized. As an aside, T(6) is formed by gluing together 945
distinct tetrahedra.
Triptych
Our goal was not to describe the space in mathematical
terms. Instead, we wanted to have the viewer experience
navigation in this novel world: How would the inhabitants
of T(5) get around their land? How would different transportation systems exist and naturally interact with one another?
In what ways would the different tree structures play a role
in such systems?
The result was a triptych of paintings titled The Cartography of Tree Space: three panels, each created on a 108 × 108
cm panel. Each panel focused on a different “layer” of the
transportation world and a different category of tree-type.
• The first painting (Underground, graphite, gouache,
ink and acrylic: Fig. 5, top-right corner) targets the 25
vertices and reimagines them as stations in an underground system. Each vertex is a circle (corresponding
closely to the vertices in Fig. 5a), and the edges of
T(5) appear as tunnels between them. These edges are
limited to horizontal, vertical and 45-degree slants,
as is common with subway maps. The tips of these
tunnels, as they appear on the circle, are consistently
color coded with the schemata in Fig. 4.
• The second piece (Woven, gouache, acrylic, gold, copper and silver leaf: Fig. 5, bottom-left corner) focuses
on the 105 edges as roads existing on the surface of
Devadoss and Schuh, Cartography of Tree Space 281
Fig. 5. Top row: Illustrator
rendering of vertices and
edges of T(5); Underground
wood panel. Bottom row:
Woven wood panel;
Unfolded wood panel.
(Top left: © Satyan L.
Devadoss. Top right, bottom
row: © Owen Schuh.)
this world. An emphasis is placed on maintaining a
five-fold symmetry as much as possible. The vertices
are represented as pentagons and are leafed with gold,
copper and silver, corresponding to distinct treetypes. Moreover, coincidences and superpositions of
individual line segments are avoided.
• The third painting (Unfolded, acrylic, ink, tea, gold,
copper and silver leaf: Fig. 5, bottom-right corner)
targets the 105 triangles presented from a vantage
point in the skies. Here the patches of land are shaded
one of three colors (60 brown, 30 golden and 15 white
triangles), corresponding to the three types of treetypes in Fig. 4. The metal leafing of the vertices also
corresponds to Fig. 5a.
In order to keep from “getting lost” in the details and complexities, the artist relied on a set of procedures to keep track
of his own location in tree space. These procedures determined the order in which the image was drawn, the angles
of the lines, how they cross and, less formally, “Lines connect
between vertices in an elegant and direct manner.” In the first
attempts, this meant drawing out all the permutations and
then numbering them and listing each tree’s connections. The
282 Devadoss and Schuh, Cartography of Tree Space
drawing proceeded down the list until it was complete, and a
rather tangled mess emerged. Later attempts made use of the
patterns and symmetries, which became apparent in this first
attempt. A different procedure would yield an equally valid
rendering, with a possibly radical look.
While a computer model would have been possible for this
project, we felt that drawings by hand were more appropriate. The computer changes the way one interacts with the
object: Although easier to manipulate and alter, this behavior
in and of itself could just as surely cause certain aspects to be
overlooked. Shoehorning tree space into a two-dimensional
frame that takes a longer time to “render” forces one to slow
down and perhaps approach it differently.
Conclusion
The mathematical definition of a line has neither thickness
nor color, but in drawing there is no line without these characteristics. As mathematics tries to create abstractions from
reality, these works show alternate realisms arising from such
abstractions. The careful selection of color and line places
the artwork in relation to other images, forms and ideas, and
creates openings for the viewer to visually experience the
structure of tree space. Although these decisions may seem
arbitrary relative to the mathematics, they are necessary for
the realization of any visual representation at all. While a
completed drawing can be apprehended “all at once” as a
whole, it still must be drawn one line at a time, similar to
the distinction between mathematical insight and the rigor
of a proof. The resulting art is not intended to decorate or
obfuscate the mathematics; rather it makes visible the work
of understanding and rendering a representation of the math
object in physical form.
At the end of this process, the mathematician had more
to say about the art, and the artist had more to inquire about
the mathematics. Not only were three visual pieces produced,
but several mathematics questions arose during the process.
(The diligent reader is encouraged to pursue Devadoss et al.
[11] for the necessary background.) In particular, the art led
to these open questions:
• Expanding on the notion of maps and cartography,
what can be said about distances between two points
in tree space? What about certain restrictions that
limit the inhabitant to avoid or use only certain
tree-types of triangles or edges? How can efficiency
of travel in tree space be measured with different
weights placed on different tree-types?
• What is the least number of chambers (in the form
of associahedra) needed to cover the tree space T(n)?
We know n!/2 such chambers is enough, but can this
Acknowledgments
We are grateful for conversations with Daoji Huang and Alyson Shotz,
along with the support of Williams College, Rebeccah Blum and Kit
Schulte (Satellite Berlin), Stephen Nowlin (Williamson Gallery). Thanks
also to the referees, who provided clear and helpful feedback.
References and Notes
1 B. Russell, “The Study of Mathematics,” The New Quarterly 1 (1907).
2 See for example M. Emmer, “Art and visual mathematics,” Leonardo
27, No. 3, 237–240 (1994); L. Gamwell, Mathematics + Art: A Cultural
History (Princeton, NJ: Princeton Univ. Press, 2016).
3 G. Anderson et al., “Drawing Mathematics: From Inverse Vision to
the Liberation of Form,” Leonardo 48, No. 5, 439–448 (2015).
4 S. Devadoss and O. Schuh, Cartography of Tree Space (Berlin: Satellite Berlin Galler, 2015).
5 L. Billera, S. Holmes and K. Vogtmann, “Geometry of the Space
of Phylogenetic Trees,” Advances in Applied Mathematics 27, No. 4,
733–767 (2001).
6 J. Boardman, “Homotopy Structures and the Language of Trees,”
Proceedings of Symposia in Pure Mathematics 22 (1971) pp. 37–58.
7 Billera et al. [5].
8 S. Devadoss, D. Huang and D. Spadacene, “Polyhedral Covers of Tree
Space,” SIAM Journal of Discrete Mathematics 28, No. 3, 1508–1514
(2014).
9 H.S.M. Coxeter and G.C. Shephard, “Portraits of a Family of Complex Polytopes,” Leonardo 25, No. 3–4, 239–244 (1992).
number decrease? In what ways would this help to
form better maps of tree space?
• Another chamber-type (permutohedra) is obtained
by permuting all the leaves of a tree in the shape of a
caterpillar [12]. What chambers do we obtain when
leaves of other tree-types are permuted? Can different
navigation maps be created using different chambers
of tree space? And what type of information would be
needed to move from navigation maps that use different chamber types?
As the triptych paintings form one result of the collaboration, this set of open mathematics questions forms another.
In all of this, the process behind the mathematics and the art
was quite similar: Ideas were conjectured, tested and evaluated, both visually and analytically. And there was a sense of
incredible freedom to explore these worlds, with a strong instinct guiding the collaborators as to the right road to pursue.
Cambridge mathematician John Littlewood, in his wonderful 1953 manuscript, commented on the modern viewpoint
of the duality between images and mathematical theory: “A
heavy warning used to be given that pictures are not rigorous; this has never had its bluff called and has permanently
frightened its victims into playing for safety” [13].
Our work is a testament towards bridging these two worlds
together.
10 S. Devadoss and J. Morava, “Navigation in Tree Spaces,” Advances in
Applied Mathematics 67 (2015) pp. 75–95.
11 Devadoss et al. [8].
12 Devadoss et al. [8].
13 J. Littlewood, A Mathematician’s Miscellany (London: Methuen &
Co, 1953) p. 54.
Manuscript received 5 October 2016.
Satyan Devadoss received his PhD in mathematics from
Johns Hopkins and became a full professor at Williams. He has
held visiting positions at Ohio State; University of California,
Berkeley; Harvey Mudd; Université Nice; and Stanford. Devadoss is a recipient of two national teaching awards as well as an
inaugural Fellow of the American Mathematical Society, with
support from the NSF, DARPA and the Mellon and Templeton
Foundations.
Initially pursuing biology, Owen Schuh earned a degree in
fine art and philosophy from Haverford College and received
his Master’s of Fine Art from the Tyler School of Art. He returned to Haverford to teach drawing and painting before moving to San Francisco. He has exhibited in Germany, Italy and
throughout the United States, and his work is included in a
number of private collections.
Devadoss and Schuh, Cartography of Tree Space 283
Manoa
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Volume 31, Number 1, 2019
University of Hawai’i Press
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In the Next Life, a Tree
Alan Michael Parker — (bio)
So I shall put on my tree hat
and my tree shirt and tree pants
and my root boots
and let my gouges show
and walk until I stay
and keep for the birds a home
and every so o!en
every so
I shall turn a little
to the light to grow
and I shall wrap
I wrap up in wind
so I can listen
to each inclination
View Citation
jealous of lightning
blind in the snow
I shall let my colors decide
the years I will wear
all of my rings
and so many arms shall I have
and never need more
to carry
to carry the sky [End Page 86]
Alan Michael Parker
Alan Michael Parker is the author of nine books, including The Ladder (2016). He is the Houchens
Professor of English at Davidson College and also teaches in the University of Tampa’s low-residency
MFA program. He lives in North Carolina.
Copyright © 2019 University of Hawaiʿi Press
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Print ISSN
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Pages
86
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2019-05-10
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