Raise your hand if you learned about Mendel and his peas in high school biology.
It is a common misconception that this model of simple genetic traits applies for all traits. As a result, many students adhere to the idea of genetic essentialism, which concludes that even complex traits like skin color and intelligence are determined solely by someone’s genetics.
Dr. Brian Donovan
This is a notion that has been widely disproven in the scientific community for the past 20 years. However, there is a clear, historical roadblock in the community’s ability to translate this to the public — in a study to be published next month in Science, this group of scientists thinks they found a way.
Brian Donovan is a senior research scientist at BSCS Science Learning, and the principal investigator for a $1.29 million NSF project studying the effects of changing genetics education in American high schools.
On Wednesday evening, he gave a special talk at Duke to a standing-room-only crowd filled with the Biology and Evolutionary Anthropology departments, as well as about 50 assorted undergrads who were scribbling notes like they were going to be tested (myself included).
This talk is especially salient for the crowd in attendance: Duke has one of the most innovative introductory Biology courses in the nation (as anyone who has taken BIO202 with Dr. Willis will tell you), aimed specifically at combatting prejudice from misconceptions in genetic education.
Biological Sciences, Room 141, packed to the brim.
Donovan’s grandparents were Holocaust survivors from Poland who experienced ethnic persecution at its highest, and he was inspired to combat these prejudices. Many people don’t realize that Nazism borrowed many of their tenets from Jim Crow laws, he discussed in the presentation. Not to mention the basic genetic model used in classrooms across the country — the Punnett Square — was developed in accordance with eugenics.
Donovan’s pitch was simple: a vaccine against racism.
According to numbers calculated in the study based on teenagers’ social media use and content, 13% of high school students in the U.S. could be exposed to racist manifestation during their high school career. And 98% of these kids take high school biology. Combatting racism with proper, well-rounded education on common misconceptions about genetics and race could be part of the solution.
But this doesn’t mean we need to nix Mendel altogether, Donovan says — we just need to restructure the narrative.
Dr. Brian Donovan giving a lecture on Wednesday in the Biological Sciences building.
The new-and-improved curriculum (called “human(e) genetics,” which is very clever, if you ask me) focused on facets of genetics that are commonly considered fact by the scientific community.
0.1% of the human genome is variable between people.
There is statistically more genetic variation within human populations than between them
Complex traits, like skin color and height, have very weak association with genetics alone.
The relationship between environment and genetics is hard to quantify exactly. Studies in humans would be very unethical.
Height is a complex trait, just like skin color, says Donovan. These traits exist on a continuum. But you don’t make assumptions about people’s background based on their relative heights, yet the continuum of height variety is just as discrete as the continuum of skin color variety.
So, if all of this is such common knowledge, why is it not taught in classrooms already? Take this quote from a 1941 textbook called Biological and Human Affairs:
“There are no studies on how that impacted kids.” Donovan declared. “But I don’t think we need one after reading that. I think we can tell.”
After crunching a lot of numbers, Donovan’s team calculated that, considering the success rate of their humane genetics curriculum in experimental groups (the number of students who changed from agreeing with genetic essentialism to disagreeing with it), 52% of the original 13% exposed to racist ideals online would be protected from following them after this new education model.
Of course, this model can be expanded to address more issues than just racial prejudices. Donovan’s team has also conducted studies on the effects of humane genetics education on gender perception.
These studies have even more relevance today in the age of controversy in history and biology education in Florida and the CRT controversy across the nation. In the question-and-answer session, students critiqued the feasibility of instituting humane genetics education in these states as a result.
The best way to educate adults, Donovan answered, is to educate the masses. “I have to ask you all,” he gestured to the room, “to publish. We need to publish papers that confirm we have a scientific consensus.”
Duke in Australia 2023 in front of 1.9-billion-year-old stone in the Northern Territory. Photo by one of our tour guides.
Australia. For years it was more of a nebulous concept to me than a concrete place. It was a colorful patch on maps, home to animals I’d read about but never seen. Now it’s a place where I’ve run my hands over 1.9-billion-year-old stone, watched a platypus emerge from a river at dawn, gotten bitten on the tongue by an ant with a tasty green butt (long story), and spent a thousand other moments with wonderful people in places I hope to never forget.
That’s all thanks to Duke in Australia, a month-long biogeography course led by Alex Glass, Ph.D., and Nancy Lauer, Ph.D., that delves into Australian flora, fauna, geology, history, and culture. When people ask about my experience there this summer, I have a hard time answering. “Wonderful” doesn’t begin to cover it. The experience still doesn’t feel entirely real to me. Even when I was in Australia, watching a platypus or a parrot or standing on a beach with a sunrise on one side and a rainbow on the other, I sometimes couldn’t entirely believe where I was.
Sunrise at Myall Beach on Cape Tribulation, where the Daintree Rainforest meets the Great Barrier Reef.
Disclaimer: When I say “Highlights from Duke in Australia,” I’m referring to my own personal highlights—some of which, let me assure you, were not universally popular with my classmates. Like the enormous crickets we saw on our rainforest night hike, or the time I found the shed skin of a huntsman spider and went around showing it to everyone nearby, or the delightfully squelchy mud coating the trail on one of our last hikes. For more detailed accounts of our day-to-day activities, check out the student blogs on the Duke in Australia 2023 website.
From the moment we landed in Sydney, I was keeping my eyes peeled for bird sightings. (I am slightly into birds. Just slightly.) Unless you count an ambiguous white flash seen through a bus window, my first bird sighting in Australia was a small group of rainbow lorikeets flying over the city. With a blue head and stomach, a green back, an orange-red breast, and flashes of yellow under the wings, the species is very well named.
Lorikeets weren’t the only birds we saw in Sydney. Common mynas, which always looked vaguely sinister to me, watched us while we ate dinner the first night. Pigeons strutted along the sidewalks—the only bird species I saw in Australia that I’d also seen in the US, except a possible peregrine falcon that I caught only a brief glimpse of during a hike. There were also Australian ibises all over the city, colloquially known as bin chickens for their dumpster-diving habits. Personally, I thought the ibises were lovely, regal birds.
There are other birds, however, that can no longer call Sydney home. One of my favorite sites in Sydney was the Forgotten Songs art installation at Angel Place. It is a short alley engraved with the names of fifty bird species that can no longer survive in the city. Empty bird cages hang suspended above the street. Our tour guide told us that the exhibit normally plays recordings of the birds, but that part was under renovation, so it was playing music instead. A few days later, I returned to the exhibit on my own so I’d have time to read every bird name. Those empty cages still haunt me.
An eleven-armed seastar in one of the tide pools at Bondi Beach. (Eleven-armed seastars do not always have eleven arms.) Below it, you can see Neptune’s necklace, a type of algae resembling strings of beads.
On our first full day in Sydney, we went to Bondi Beach to explore the tidepools. There were crabs and octopi, seastars and anemones, necklace-like algae and tiny blue snails called little blue periwinkles. That afternoon, we sat on the beach and learned about microplastics from Lauer. (Not-so-fun fact: we eat a credit card’s worth of microplastics every week on average.) Some of us lingered on the beach afterward and went swimming. The water was frigid, but it was there, with cold water and sand swirling around me in a part of the ocean I’d never seen, much less swum in, that the reality of being on a new continent completely hit me.
Sunshine wattle flowers on our hike at North Head, viewed through a hand lens.
Our first group hike was overwhelming, almost dizzying. Outside of urban Sydney, it was easier for me to recognize just how different Australia was from the US, and it was impossible to absorb everything at once. In every direction were unfamiliar plants and landscapes. Norfolk pine, coastal rosemary, mountain devil, sunshine wattle, Darwinia, flannel flower, gray spider flower…. I was especially entranced by casuarina, which looks shockingly like a pine tree but is actually a flowering plant that has evolved conifer-like traits to preserve water. We were in a heath, characterized by low-growing plants adapted to dry, nutrient-poor conditions. Nothing about it looked like the woods and fields and mountains back home.
Our focus that day was studying plants, but I was having a hard time focusing on any one thing for more than about a second. At one point, we were supposed to be observing a beautiful plant to my right, but half the group had already moved on to another species farther up the trail, and meanwhile, a bird I had certainly never seen in my life was perched remarkably cooperatively on a bush off to the left. There are too many things happening, I remember thinking. I was juggling my field notebook, hand lens, phone camera, and binoculars, and I didn’t even know where to look. I chose to stare at the bird, following the logic that it could fly away at any moment, whereas the plants would stay exactly where they were. That brilliant plan turned out to be faulty. The plants might stay still, but we wouldn’t—so much to see, so little time.
A galah, a species of cockatoo, in Katoomba.
Our next stop was Katoomba, a small mountain town in New South Wales. It was a quiet, peaceful place, vastly different from Sydney. When I think of Katoomba, I think of the sulfur-crested cockatoo perched on a bakery sign just feet away from me and the flock of strikingly pink cockatoos called galahs in a local park. I think of the superb lyrebird that crossed our path directly in front of us and the rare Wollemi pine growing beside a road.
We took a hike at Wentworth Falls, where Darwin himself once walked. It’s part of the Great Dividing Range, but we learned that the mountains are actually “incised terrain,” formed when valleys were cut into a plateau, leaving “mountains” behind. We also drove to the Jenolan Caves and explored cavernous underground spaces bursting with crystal formations like stalactites, flowstone, and hollow soda straws. These lovely, fragile cave structures, or speleothems, are formed by the gradual deposition of dissolved minerals as water drips through a cave. Before we left, we saw an underground river with water so clear that I didn’t immediately realize I was looking at water at all.
Part of the Jenolan Caves. Gradual geologic processes form decorative structures, or speleothems, in caves.
Another day in Katoomba, our group took a gorgeous hike through a eucalypt forest. Literally everywhere I looked in that forest, there was something extraordinary. Ancient tree ferns. Ruby-red sap seeping out of a tree trunk. The Three Sisters rock formation framed by the aptly named Blue Mountains. Towering eucalypt and turpentine trees. At the end of the hike, we rode the Scenic Railway, the steepest in the world. It was terrifying—awesome, but terrifying.
A view from one of our hikes in the Blue Mountains.
Next, we flew to the Northern Territory, where we checked into our hostel in Darwin. We were now in crocodile country, home to the world’s largest reptile: the saltwater or estuarine crocodile. We were instructed to avoid going in any body of water, saltwater or otherwise, unless it was specifically designated as safe for swimming. (The name “saltwater crocodile” is misleading—the crocodiles can inhabit fresh water as well, and they are extremely aggressive and dangerous.) It was very important to be crocwise.
A rainbow bee-eater at the George Brown Darwin Botanic Gardens in Darwin, a city in the Northern Territory.
The first few days in Darwin, we didn’t see any crocodiles, but there were birds seemingly everywhere. Varied triller, which I originally misidentified as the buff-sided robin until a local eBird reviewer emailed me and asked me to correct my eBird report. Rainbow bee-eater, remarkably common for a bird that looks too beautiful to be real. Peaceful dove. Blue-faced honeyeater. Australasian figbird.
We took a hike that went through a beautiful mangrove, where we learned that the term mangrove isn’t specific to any particular type of plant; it’s used to refer to many very different species that have all adapted to the same challenges, including salinity, changing tides, and nutrient-poor soil. There were crabs and snails and birds—so many birds, some of which I still haven’t identified, like the group of black, crested birds with bright red inside their beaks.
Green weaver ants. Note their distinctive green abdomens, which contain ascorbic acid and have an interesting taste.
When we emerged from the mangrove, we came across a nest of green weaver ants. Their bright green abdomens are rich in ascorbic acid, and the ants have traditionally been used for purposes ranging from treating colds to making a sort of “lemonade” to stimulating milk production. Many of us were eager to taste the ants, though Glass warned us that they “bite vigorously.” Some of my classmates carefully held an ant with their fingers while giving the abdomen a quick lick. I, on the other hand, decided to let an ant crawl onto my notebook while I licked it so it couldn’t bite my fingers. Clever, right? Well, it worked—the ant didn’t bite my fingers. It bit my tongue instead. “Vigorously.” Its mouthparts remained latched on even as I was spitting out ant parts onto the ground. I can’t blame it—I’d be upset, too, if a giant tried to lick me.
Before long, it was time for the jumping crocodile tour. We boarded a tour boat and floated down a seemingly peaceful river while our guide dangled hunks of meat from big fishing rods to bait the crocodiles to leap several feet out of the water and snap their jaws around the food. Their bite force, incidentally, is the highest of any living animal, up to 3700 pounds per square inch. Jumping is natural for the crocodiles—they hunt that way to snag animals like birds and wallabies that venture too close to the water. Being that close to enormous predators roused some deep, primeval fear in me. To a crocodile, I would make excellent prey. The jumping crocodile tour, needless to say, was very memorable. Our class later had a long and far-ranging discussion on the many types of ecotourism experiences we’d participated in and their costs, benefits, and ethical implications.
One of the crocodiles on the jumping crocodile tour.
The next day, we left for a three-day camping trip in Kakadu and Litchfield National Parks. It was the dry season, and the weather was hot, dry, and sunny. We went hiking and snorkeling (in croc-free swimming holes), saw the breathtaking magnetic and cathedral termite mounds, and learned about geology and Aboriginal cultures. Some of the places we visited were sacred sites of the people who have inhabited the region for more than 65,000 years. One of the rock art paintings we were able to see was of a Tasmanian tiger, an animal that’s been completely extinct for close to a century and extinct in the Kakadu region for thousands of years. But right there on the wall was the preserved memory of a time when Tasmanian tigers still roamed the area.
Me with a stick insect at our campground in Kakadu National Park in Australia’s Northern Territory. Photo by Letar Jia, another student in the Duke in Australia program this summer.
One of the coolest places we stopped was a rock cut-out along a highway. The stone was striped with zigzagging layers created when it was buried underground at a pressure high enough to fold solid rock. It was formed 1.9 billion years ago, when the earth was “a geologist’s dream,” according to Glass–relatively barren, with no soil, plants, or animals, just microscopic organisms and lots and lots of rock. I was touching 1.9 billion years of history.
We spent the third night at a different campsite. Some of us spotted what seemed to be a large spider in the bathroom, but one of the tour guides informed me that it was actually just the shed skin of a huntsman spider, not the spider itself. I walked around camp introducing people to my “little friend,” but oddly enough, they didn’t seem as delighted as I was.
That night, while we were theoretically sleeping, periodic cacophonies of eerie, wailing screams reverberated through the air. My half-asleep brain was convinced they were from wallabies, but the sound actually came from a bird called the bush stone-curlew or bush thick-knee. The next morning, there was a gecko in the bathroom, and I wasn’t sure my day could possibly get any better. But later that day, we visited a fragment of an ancient rainforest, and there were giant fruit bats practically dripping from the canopy and giant golden orb weaver spider webs strung between trees, and I think that was even better than the bathroom gecko.
A female giant golden orb weaver, with my hand for scale. The tiny, orange spider on her back is the male.
After departing Darwin, we headed to Cape Tribulation, where the Great Barrier Reef meets the Daintree Rainforest—believed to be the oldest rainforest on the planet. Some rainforests, Glass explained, exist because they’re near the equator. But the rainforests in Australia are remnants of ancient rainforests that developed when the continents were arranged very differently and Australia was considerably farther south. Australia’s climate has become more arid over time, but pockets of its ancient rainforests remain intact.
While we were on Cape Tribulation, we had the chance to snorkel on the Great Barrier Reef. It was overcast and very windy that day, and the small boat that took us out to the reef turned into a rollercoaster as it slid up and down waves. But windy or not, the reef was gorgeous. We saw sea turtles, a sea cucumber, a small shark, and fishes and corals in endless colors.
We also had the incredible opportunity to hike through the rainforest at night. Of all the amazing things we did, that may have been my favorite. There were huge crickets and spiders, thorny vines called wait-a-whiles (because you’ll be waiting a while if you get stuck on one), and flowering plants that looked like mushrooms. And partway along the boardwalk, Glass spotted a creature so unusual and elusive that he had never seen one before. This, he told us, was probably the rarest animal we’d seen on the whole trip. A velvet worm. It looked a bit like a caterpillar or a centipede at first glance, but velvet worms have an entire phylum all their own. (Caterpillars and centipedes share the Arthropoda phylum, along with all insects, spiders, crustaceans, and various others. Velvet worms are in the Onychophora phylum.) The ancestors of velvet worms are thought to represent a link between arthropods and segmented worms. They are ancient, unique, and rarely seen.
The velvet worm.
Just moments later, Glass announced another incredible find: a peppermint stick. I raced ahead to see it. Earlier that day, I’d seen signs about peppermint stick insects, which excrete a peppermint-scented liquid as a defense mechanism, and I’d been keeping my eyes peeled ever since. The creature had developed a sort of mythical status in my mind; I’d been fantasizing about seeing one but hadn’t actually expected to. But there it was, right in front of us, large and stick-like, its color a blue-green so bright that it almost seemed to glow.
A platypus in a river in Yungaburra.
In Yungaburra, our next-to-last stop, we saw enormous fig trees and gorgeous waterfalls. On our last morning, several of us left the motel around dawn and walked to a nearby trail along a river in search of the platypus and the tree kangaroo, an arboreal kangaroo species. We found both. It was a fitting almost-ending to our trip. Both platypuses and kangaroos seem so iconically Australian. The platypuses slipped in and out of the water, their dark bodies visible even in the low light. The tree kangaroo watched us silently from its perch above us and then slowly began to move elsewhere.
A tree kangaroo in Yungaburra.
Before long, it was time to go home. We spent a couple days in Cairns first, where I saw a shiny, emerald green beetle and a tree positively full of squawking lorikeets. Even in the city, there were bright and beautiful animals. In places like the ones we visited, it is easy to find awe and wonder and beauty everywhere you look. But there are endless treasures here, too, fascinating and beautiful sights that we walk past every day, like the way spiderwebs turn silver in the sunlight, or the gray catbird that eats bright red magnolia fruits in the courtyard in front of my dorm window, or the tiny, bluish purple flowers on the Al Buehler Trail, soft and fuzzy and damp when I brushed my face against them. Duke in Australia was an unforgettable adventure. It was also a reminder to step out of the human bubble and immerse myself in the worlds of other living things—whether here or across the globe.
We didn’t know we needed another way to rank the importance of Duke’s scientists, but the folks at research.com have gone ahead and developed one anyway. And in its second year of data, several Duke people come out in the top ten nationally and globally. So, okay, maybe we did need a new ranking system!
Duke Psychology and Neuroscience swept the U.S. medals in psychology: Terrie E. Moffitt Ph.D., first, Michael Tomasello, Ph.D. second, and Avshalom Caspi, Ph.D. third. Duke University’s psychology is overall ninth in the world, according to this ranking.
Moffitt, the Nannerl O. Keohane University Distinguished Professor of P&N, and Caspi, the Edward M. Arnett Distinguished Professor of P&N,are frequent co-authors on a lifelong psychology and health study of 1,000 people born in Dunedin, New Zealand. Moffitt ranks fourth in the world in psychology, with 207,903 citations of her 582 works. Caspi’s 159,598 citations of 507 papers were good enough for 10th in the world.
Developmental psychologist Tomasello, the James F. Bonk Distinguished Professor of P&N, has focused his work on cognitive development, social cognition and language acquisition. He has 147,951 citations on an even 800 works, placing him second in the U.S. and ninth in the world.
Nobel laureate Robert Lefkowitz M.D., the chancellor’s distinguished professor of medicine, is ranked second in the nation and third in the world for Biology and Biochemistry with 198,000 citations of his 881 papers. The rankings reflect the importance of Lefkowitz’s discovery and characterization of the 7-transmembrane g-coupled protein receptor (GPCR), a fundamental signaling port on the surface of cells that is targeted by a third to a half of all prescription drugs.
Koenig
Psychiatry and Behavioral Sciences professor and Co-Director of Duke’s Center for Spirituality, Theology and Health, Harold G. Koenig M.D., was ranked seventh in the nation and 10th in the world for Social Sciences and Humanities for his work on spirituality and health. His 703 publications have earned 66,404 citations.
Many other Duke scholars finished in the top 100 worldwide in their respective fields, some even making a mark in multiple fields. Check it out.
Methodology: Research.com’s ranking of the best scholars by discipline relies on data consolidated from various sources including OpenAlex and CrossRef. The bibliometric data for estimating the citation-based metrics were collected on Dec. 21, 2022. Position in the ranking is based on a researcher’s D-index (Discipline H-index), which includes exclusively papers and citation metrics for an examined discipline.
And just to prevent some letters to the editor, we acknowledge that the H-index has its critics, including its inventor. We don’t make the rankings folks, we just share them.
Clockwise: Jonathan Shaw, Adam Kosinski, Natalie Farris, and Kavya Menke looking at bryophytes on a log.
On a bright Sunday afternoon in April, I did something I had never done before. I went for a walk in the woods specifically to look for mosses. No, that’s not strictly true — we were looking for bryophytes. I learned, among other things, that not everything I had always called moss was really moss at all. (The word bryophyte comes from ancient Greek components and literally means “moss plant.”)
A patch of moss on the Al Buehler Trail. Moss is one type of bryophyte; liverworts and hornworts are the two others.
The walk was organized by Wild Ones, an undergraduate nature club I’m involved with. Biology Professor Jonathan Shaw, Ph.D., and Blanka Aguero, data and collections manager in the Duke University Herbarium, volunteered to teach a group of undergraduates about mosses and other bryophytes on the Al Buehler Trail adjacent to the Duke golf course.
Jonathan Shaw and members of the Wild Ones holding moss. Mosses, liverworts, and hornworts together represent the bryophytes.
Bryophytes (which include mosses, liverworts, and hornworts) represent one of several large groups of terrestrial plants. Other groups include angiosperms (flowering plants), gymnosperms (cone-producing plants like conifers and ginkgos), pteridophytes (vascular, spore-producing plants including ferns and horsetails), and lycophytes (an ancient group with about 1200 surviving members). According to Shaw, bryophytes are “the second biggest group after the flowering plants, but the flowering plants are an order of magnitude more diverse.” Aguero says that North Carolina has 462 moss species, 211 liverworts, and 7 hornworts.
Zach Pracher (Wild Ones member) and Blanka Aguero looking at bryophytes on a log.
Unlike the other terrestrial plant groups, bryophytes are nonvascular, meaning they lack the water transport tissues that other plants use. Without vascular tissue and without lignin for support, bryophytes can’t grow very big because they have no way to efficiently move water from their base to the rest of the plant. Instead, they grow close to the ground and absorb water directly from the environment into their cells.
Despite their preference for damp habitats, bryophytes can live for a long time without water. Some plants (like cacti) survive droughts by storing water, but bryophytes have a different strategy. They go into a state of dormancy, or suspended animation, and simply wait. Then, when it next rains, “they go hog-wild, photosynthesizing again in minutes,” Shaw says.
So if bryophytes don’t rely on constant moisture to survive, why do they like it so wet? Water, as it turns out, isn’t just important for hydration. Bryophytes rely on it to reproduce as well.
“Mosses are the amphibia of the plant communities,” Shaw says. Just as many amphibians can live on land but must return to the water to reproduce, bryophyte sperm has to “swim” to an egg cell to fertilize it. Therefore, they need water in order to reproduce, but they don’t need much. It could be mist from a splashing waterfall or a puddle in the woods or rainwater trickling down a tree. It could even be dew.
Moss on a tree trunk. Bryophytes can grow in a wide range of habitats across the world.
The day was warm and sunny, but the ground was dotted with puddles from recent storms. Armed with small hand lenses, we set off down the trail, stopping periodically to scrutinize tree bark, fallen logs, and thick patches of moss on the forest floor.
You need not travel far to find bryophytes. Mosses and their cousins colonize all sorts of hidden nooks: damp logs, trailside divots, tree bark, riverbanks, forgotten corners of backyards. Compared to seed-producing plants, bryophytes tend to have larger geographic ranges, perhaps in part because spores disperse more easily and because bryophytes can survive dry spells. Shaw estimates that about 75% of the moss species found in North Carolina are also found in Europe, and some of them are found in Asia as well.
Atrichum moss viewed through a hand lens. Note the thin line down the middle of each leaf. That line is a midrib and is one feature that sets mosses apart from liverworts.
We learned that most mosses have a midrib in the middle of each leaf, whereas liverworts have no midrib.
“A liverwort,” Shaw explains helpfully, “is like a moss, but it’s a liverwort.”
Liverworts are relatively flat in comparison to mosses because their leaves are in two parallel rows, whereas mosses tend to have a more spiral shape, with leaves emerging from all sides of the stem. The flat appearance of liverworts explains why they are sometimes called scale mosses. Another feature to consider if you’re trying to distinguish mosses and liverworts is the presence of lobed leaves, or leaves with protuberances off the main leaf (think of maple or oak leaves, for example). Some liverworts (but not all) have lobed leaves, but no mosses do.
A liverwort (main image) and the same liverwort viewed through a hand lens (top right). Liverworts and mosses can look very similar, but a hand lens makes it easier to spot the differences between them. Note the relatively flat appearance of the liverwort leaves compared to moss leaves, which tend to grow in a spiral fashion around the stem.
Aguero and Shaw both point out that the features we use to visually distinguish bryophytes aren’t necessarily the same features that officially set mosses and liverworts apart. The main difference between mosses and liverworts involves differences between their sporophytes.
Frullania is a genus of liverworts that forms dark patches, like the spots on this tree. If you see patches like these, Aguero says, they are “invariably” Frullania liverworts.
“It’s not true that if you’ve seen one moss, you’ve seen them all,” Shaw says. They’re small, yes, but they are not all the same.
We looked at one particularly lush patch of moss in the Bryoandersonia genus, named after a Duke professor. If you’re trying to identify trees, Shaw says, you might start with features like whether the leaves are broad or narrow and whether the tree is shrubby or not. With mosses, on the other hand, one of the first questions to ask is whether it’s pleurocarpous or acrocarpous. Pleurocarpous mosses, such as the Bryoandersonia we looked at, tend to have highly branching stems and grow in sprawling patches. The stems of acrocarpous mosses, meanwhile, have little or no branching and grow mostly vertically, often forming tight clumps.
Kavya Menke (Wild Ones member) examining a thallose liverwort we found by a stream.
After learning about patches of Frullania liverworts on trees from Aguero, we examined a large clump of liverworts growing beside a stream. Unlike the other liverworts we’d seen, this was a type of thallose liverwort, set apart from so-called leafy liverworts by the presence of thallus (a ribbon-like structure) instead of leaves. We also had the chance to smell it. Interestingly, liverworts also have a distinctive smell, sharp and earthy. The scent can be so strong that you might sometimes smell liverworts before you see them.
A thallose liverwort in the genus Conocephalum. Thallose liverworts are characterized by thalli (plural of thallus) instead of leaves. The other liverworts we saw were leafy liverworts. Photo by Adam Kosinski.
According to Shaw, the term liverwort dates back to when botany and herbal medicine were considered largely the same. The so-called Doctrine of Signatures is the long-held idea that plants’ physical features reveal their medicinal uses. Thallose liverworts were thought to resemble livers and were used to treat ailments of the liver, hence the name. Similarly, the walnut looks rather like a brain and was used to treat mental illness, while the Dutchman’s breeches flower (the white flowers are said to resemble pants) was used for sexually transmitted diseases.
Aguero says that some liverworts do contain chemicals with antimicrobial properties, but she advises people not to eat liverworts.
Moss sporophytes, which release spores into the air. (Top right: close-up through hand lens.) The sporophytes are the only part of a bryophyte that are diploid (containing two sets of chromosomes instead of one). The trees in the background are also diploid; most plants (with the exception of bryophytes) are diploid during most of their life cycle. Photos by Adam Kosinski.
Near the end of our walk, we found something we’d been keeping an eye out for but hadn’t yet seen: moss sporophytes. Bryophytes have a unique life cycle. Most of the time when we see a plant or an animal, it is diploid, meaning each cell contains two full sets of chromosomes (one from each parent). Every human cell, for instance, contains 46 chromosomes—with the exception of female egg and male sperm cells, which contain only 23. Cells that have only one set of chromosomes (like human egg and sperm cells) are called haploid. Plants undergo alternation of generations, meaning that one phase in their life cycle is haploid and one is diploid. In the case of most plants, the dominant and most conspicuous part of the life cycle is the diploid phase, but bryophytes are different. The fuzzy green carpets of moss we see are made of haploid cells, while the diploid phase is short-lived and only appears during reproduction. In mosses, the diploid phase (also known as the sporophyte) resembles thin filaments emerging from the haploid bed of moss. These sporophytes release spores (the spores are haploid) that grow into the next generation of moss.
“I wish we could be like the moss spores and let the wind carry us,” said Kavya Menke, one of the undergraduates on the walk. “Cheaper than Uber.”
Clockwise: Wild Ones members Natalie Farris, Adam Kosinski, and Zach Pracher examining patches of Frullania, a liverwort genus.
Occasionally, I paused my own bryophyte observations to watch others watching bryophytes. I found myself wondering if people are similarly bemused when they see me standing in a swamp with binoculars or crouching down on the way to class to move an earthworm off the sidewalk. I am accustomed to the world of birding, and looking for creatures like dragonflies, snakes, and salamanders feels natural to me as well. But this was a delightful opportunity to enter a world in which I had little to no experience: the shady, damp world of the bryophytes.
Adam Kosinski taking a close look at a bryophyte specimen placed on a log.
If you make a habit of going on walks with birders, you may spend a lot of time waking up before dawn, craning your neck upward, and straining to hear the alleged differences between a dozen kinds of short chirps. If you go out looking for snakes, you might spend a warm afternoon flipping over sun-warmed boards and scanning rocks and other basking spots. Searching for salamanders will likely involve scrutinizing wet soil, leaf litter, and ponds in early spring, possibly on a dark and rainy night. But searching for bryophytes is an experience all its own.
For one thing, you can go at any time of day and be equally successful, seeing as bryophytes neither crawl nor slither nor fly. You can also feel free to move as slowly as you wish. Aguero compares bryologists to lichenologists: “Moss people and lichen people work together frequently,” she says. “We walk similarly slowly.”
Blanka Aguero discussing bryophytes with students. Photo by Adam Kosinski.
You could walk the same trail a hundred times and see it a hundred different ways. You could focus on birds or earthworms or snakes, wildflowers or changing leaves, clouds or trees or rocks. The next time you are in the mood to explore a new world, consider taking a walk — either somewhere new or a path you’ve walked a hundred times before — and turning your attention to the wonderful world of the bryophytes. Pet the moss. Feel its springiness and dampness and softness. Run your fingers lightly over the thin sporophyte stalks and notice how they tickle your palm. Smell the liverworts. See the dark patches of Frullania on a tree trunk. Bryophytes are nearly everywhere. Look for them. Look at them. See them.
Bryoandersonia moss viewed through a hand lens. Photo by Adam Kosinski.
Naturalist Tom Earnhardt on Black River in North Carolina. The forests around Black River are home to the oldest trees in eastern North America, 2,700-year-old bald cypresses. All photos courtesy of Tom Earnhardt.
There are many ways to think of North Carolina. It was the 12th U.S. state to enter the Union. It is bordered by Virginia, Tennessee, Georgia, and South Carolina. North Carolina’s capital city is Raleigh, and it has an estimated population of 10,698,973. These are all facts, but they tell only part of the story: the human side of it.
Naturalist Tom Earnhardt offers other ways to view North Carolina: the state contains the oldest forest in the eastern United States, with trees up to 2,700 years old. It has 17 river basins, and some of its rivers show evidence of fishing weirs used by indigenous tribes hundreds of years ago. And from the Atlantic coast in the east to the Appalachian mountains in the west, North Carolina is home to thousands of native plants, animals, and fungi. There are 3,000 species of moths alone in North Carolina, and “Every one is essential; not one is optional.”
“North Carolina,” Earnhardt says, “is still one of the most biodiverse and extraordinary places on the planet.”
A prothonotary warbler. Prothonotary warblers inhabit swamps and coastal rivers in North Carolina. They are one of only two warblers in America that nest in cavities.
Earnhardt is a naturalist, photographer, writer, and attorney. He wrote and produced the show “Exploring North Carolina,” a series of dozens of episodes about North Carolina’s biodiversity, geography, and history. Earnhardt recently visited Duke to speak at the Nasher Museum of Art.
One inspiration for his talk was the ongoing Nasher exhibit “Spirit in the Land,” an exploration of ecology, culture, and connection to the natural world. “Art in its many forms,” Earnhardt says, “tells a story of love, loss, and renewal.”
Black River in North Carolina.
Earnhardt has spent much of his career balancing caution and hope. We are facing environmental crises, including climate change and biodiversity loss. Earnhardt believes it’s important for people to know that, but he has put a lot of thought into how to get that message across. Earnhardt has learned that it can help to “tell it as though it was your best friend or brother who needed to hear an important story.” Science alone isn’t always enough. “To hear bad news of any kind is not easy,” Earnhardt says, “and people want to hear it from people they know, people they trust or can relate to.”
The stories he tells aren’t always easy to hear, but they are important. We need to know — whether on a local, state, national, or international scale — what exactly we stand to lose if we continue on a path of environmental destruction. Many species are becoming more scarce, Earnhardt says, “but we still have them.” They can’t be protected once they’re gone, but many of them are still here and can still be preserved. The goal for all of us should be to keep it that way.
North Carolina, Earnhardt says, is at “the epicenter of the temperate world.” The state has a range of climates and habitats. It marks the northernmost native range of the American alligator, while coniferous forests in the North Carolina mountains resemble boreal forests of the northern U.S. and Canada. North Carolina, according to Earnhardt, contains “whole ecosystems that other states only dream about.”
Eastern North Carolina is characterized by beaches, salt marshes, and other coastal ecosystems. Here you can find “wildflowers that grow in salty sand” and painted buntings, multicolored songbirds unlike any other in North America. On four occasions, he’s even seen manatees in North Carolina.
A male painted bunting, a summer resident on North Carolina’s barrier islands. Female painted buntings are bright green.
“Travelers from around the world vacation here and raise their families in the summer,” Earnhardt says—and he’s not talking about humans. Many shorebirds and sea turtles lay their eggs on North Carolina’s beaches. Human disturbance, including artificial lighting and crowded beaches, can put their babies in danger. Minimizing light pollution near beaches, especially during turtle nesting season, and staying away from nesting shorebirds can help.
A longleaf pine savanna in southeastern North Carolina.
Moving farther west, we can find savannas of grasses and pine trees. “You drive past this, and people go, ‘ho hum, a pine barren.’” To that Earnhardt says, “Look a little closer.”
White-fringed orchids, one of North Carolina’s 80 native orchid species. Earnhardt took this photo in the Green Swamp, a longleaf pine savanna nature preserve.
These pine barrens are home to some of North Carolina’s 80 species of orchid, like the white-fringed and yellow-fringed orchids. “Look at them from all angles,” Earnhardt urges, “because from up above it becomes a sunburst… for those who watch.”
A yellow-fringed orchid, viewed from the side.
Be one of those who watches.
A yellow-fringed orchid, viewed from above.
North Carolina rivers, forests, and swamps are also home to many wildlife species. Forests around Black River contain “huge buttresses of tupelo that hold the world together” and bald cypresses that have been alive for 2,700 years. The early years of these now-ancient cypress trees coincided with the fall of the Assyrian Empire and the establishment of the first emperor of Japan. Many centuries later, they are the oldest trees in eastern North America.
Cypress trees on Black River. Both tupelos and cypresses have buttresses at their bases to provide stability in the water.
They are also in danger. “If seas rise three feet,” Earnhardt says, “there will be enough pressure to flood these [trees]…. We could lose them.” But “they are worth saving.”
Still farther west are the Appalachian mountains, another biodiversity hotspot. North Carolina is home to 60 species of salamanders, many of which live in the mountains. The southern Appalachians and western North Carolina contain more salamander diversity than anywhere else on the planet. One species that lives here is the American hellbender, a two-foot-long denizen of mountainous streams.
Despite increasing human development, North Carolina is still rich in flora and fauna. “We have wild places,” Earnhardt says. North Carolina has more than 450 bird species, over 30 native pitcher plants, 20 freshwater turtles, and 38 snakes—“and they’re all good neighbors,” Earnhardt adds.
Venus flytraps in a longleaf pine savanna.
North Carolina has pink and yellow lady slippers and ten-foot-tall Turk’s Cap lilies; crayfish and thousands of mushrooms; native azaleas and insects that depend on them. It has Earnhardt’s “new favorite bird,” the swallow-tailed kite, and vultures, “the clean-up crew: not optional.” That’s a refrain throughout Earnhardt’s talk. “Nothing I’ve shown you tonight is optional,” he says.
“Both in banking and nature,” Earnhardt says, “when we make too many withdrawals and not enough deposits… there’s a deficit.” There are too many creatures we have already lost. The eastern cougar. The Carolina parakeet. The passenger pigeon. Too many more. There are still others that are threatened or endangered but not yet gone. “We humans tend to forget the failures and close calls,” Earnhardt says. While talking about biodiversity loss, he references a quote by biologist E.O. Wilson: “This is the folly our descendants are least likely to forgive us.”
A swallow-tailed kite. Earnhardt says that these kites, which spend their winters in South America, now nest along several rivers in southeastern North Carolina.
So what can be done? To preserve biodiversity, we have to consider entire ecosystems, not just one endangered animal at a time. “We are part of the natural world, part of links and chains and pyramids,” Earnhardt says, and humans too often forget that. Everything is connected.
He recalls visiting entomologist Bill Reynolds’s lab and noticing crickets hopping across the floor. “Don’t step on the transmission fluid!” Reynolds warned. He was referring to the crickets and to insects more broadly. Like transmission fluid in cars, insects are essential to making sure the systems they are part of run smoothly. Insects serve crucial roles in food webs, pollination, and decomposition. Studies show that they are declining at alarming rates.
“We are at a crossroads,” Earnhardt says. “Our transmission fluid is low, and we have made too many withdrawals from the bank of biodiversity.” Still, he emphasizes the importance of not giving up on wildlife conservation. Given a chance, nature can and will regenerate.
Tupelo tree buttresses on Tar River near Greenville, North Carolina.
Despite all our past and current failures, conservation also has remarkable success stories. The brown pelican is one North Carolina resident that almost went extinct but has since “come back in incredible numbers.” The bald eagle is another. Its population plummeted in the 20th century, largely due to the insecticide DDT as well as habitat loss and hunting. By 2007, though, after intensive conservation efforts, it had rebounded enough to be removed from the endangered species list. Until about 1980, Earnhardt had never seen a bald eagle in North Carolina. Today, Earnhardt says, “I see them in every county.”
A bald eagle that Earnhardt saw near the Raleigh-Durham airport. Bald eagles, once on the brink of extinction, can now be seen in every county in North Carolina.
“Everyone’s going to have to fly in the same direction,” to preserve North Carolina — not to mention the rest of the world — at its best and wildest, Earnhardt says. But individual actions can make a difference. He suggests planting native flowers like milkweed and coneflower, both of which are good food sources for pollinators. And if you choose to plant ornamentals like crepe myrtle, “Treat that as a piece of art in the yard and then plant the rest as native.”
Lady Bird Johnson, a former first lady and conservation advocate, once said that “Texas should look like Texas, and Mississippi like Mississippi.” Choosing native plants can be a powerful way to help native wildlife in your own yard. “If you plant it,” Earnhardt says, “they will come.”
One audience member asks, “How do you recommend that we recruit non-believers?” It’s a conundrum that Earnhardt has put a lot of thought into. “It takes time, and it takes patience,” he says. “Some of my best friends are not full believers, but I work on them every day.”
Geer Cemetary in Durham is one of many burial grounds in America that hold the remains of thousands of Black Americans from the 19th century. There are no records of the people buried there. The process of researching grounds like these as a form of reparations to descendent communities was pioneered by Michael Blakey in the African Burial Ground Project in Lower Manhattan, New York. He is currently the Director of the Institute for Historical Biology at the College of William and Mary.
On April 4, Blakey visited Duke as a guest of the Franklin Institute of Humanities, the Department of Classical Studies, the Department of International Comparative Studies, and Trinity College. In attendance to his lecture were students of Classical Studies 144: Principles of Archaeology with Alicia Jimenez, International Comparative Studies 283: Death, Burial, and Justice in the Americas with Adam Rosenblatt, and several graduate students by invitation (and me). His presence was clearly highly anticipated.
I initially approached Dr. Jimenez with my interest in bioarchaeology in January as I was planning my Program II application. She invited me to this seminar, and to lunch with Blakey and the graduate students beforehand. I came prepped with questions on osteopenia and hypertrophy, as well as a map of Brightleaf Square so I wouldn’t get lost (I still got lost) and a few dollars cash for parking (they only took card).
For those of you who have ever loved the detective fiction heroine Temperance Brennan, Blakey’s work is for you. He is co-chair of the Commission for the Ethical Treatment of Human Remains through the American Anthropological Association. He was claiming the title of bioanthropologist before it was cool. He wrote a guide for the profession called Engaging Descendant Communities, or, more lovingly, The Rubric. Blakey encourages allowing those descendant communities to guide scientists’ research on human remains. He calls us Homo reminiscens, because what makes us “human” may be our affinity for memorializing our dead as much as it may be our large brains (á la Homo sapiens). “Burial is human dignity,” Blakey announced during the seminar, “Dignity is what we do.”
“Ethical code is not law. It is our greatest responsibility.”
Michael Blakey
After all, science has historically been used to justify the unjust. Bioarchaeology is a famous contributor to the field; the pseudoscience of phrenology was upheld until well into the 20th century, and was originally used as “scientific proof” that people of African descent were lesser than Europeans. It was also cited as a justification for displacing Native Americans from their lands.
During lunch, I was struck by Blakey’s cadence. He had a deep, slow voice and spoke with intention. He ordered the giant pretzel. I never asked my questions; instead, I was swept away by the group’s discussion on ethics–a topic I had no open Safari tabs on. I asked instead why a scientist would choose to guide themselves entirely by a non-expert opinion rather than scientific inquiry; would that not hinder discovery?
The scientific method, as you may recall, starts with asking a question. Rather than gracefully including descendent communities after the paper has been written, Blakey urges scientists to only pursue questions about remains that the descendants wish to answer. The science of death should never be self-serving, he noted. There is no purpose to publishing a paper if it is not in the service of the community that provided the subject. A critical reader may notice that The Rubric is not called The Gospel or The Constitution. Rather than a rule of law, it is a guideline. That’s because ethics is based on the respect of self, of craft, and of others. “Ethical code is not law,” Blakey reminds scientists. “It is our greatest responsibility.”
Geer Cemetary has been the subject of Duke research for years now, from a Story+ program to class field trips. Members of ICS, CLST, and FHHI have been in cooperation with Friends of Geer Cemetary to answer such questions about burial conditions–the attempt at dignity granted to Black residents of Durham by their descendants.
Edit: a previous version of this article had incorrectly stated that the Department of African and African American Studies sponsored Michael Blakey’s lecture.
I recently had the pleasure of attending Professor Janet Malek’s lecture: Only Mostly Dead? The Evolving Ethical Evaluation of Death by Neurologic Criteria, a lecture sponsored by the Trent Center for Bioethics, Humanities & History of Medicine.
Dr. Malek is an associate professor in the Duke Initiative for Science & Society, and at the Baylor College of Medicine Center for Medical Ethics and Health Policy.
Janet Malek Ph.D.
We don’t often talk about death. On the surface, it seems like it would be a straight-forward concept. You’re either dead, or you’re not dead. Right? It turns out that clinically defining death is not so simple.
Popular media has some grasp on the ambiguity of the definition of death. Remember this scene from the popular movie, The Princess Bride? Suspecting that the protagonist is dead, his friends bring him to a miracle-worker and have the following conversation.
Miracle Max: “Whoo-hoo-hoo, look who knows so much. It just so happens that your friend here is only MOSTLY dead. There’s a big difference between mostly dead and all dead. Mostly dead is slightly alive. With all dead, well, with all dead there’s usually only one thing you can do.
Inigo Montoya: What’s that?
Miracle Max: Go through his clothes and look for loose change.
In real life, death used to be determined by cardiopulmonary criteria – when the heart and lungs stop working. In recent decades the idea that death can be determined using neurologic criteria – when the brain stops working – has gained acceptance. As neuroscience and technology has evolved, so too have our definitions. Now that we know more about how the brain works, we know that there may be some brain activity even after a person has met the criteria for death by neurologic criteria (DNC). This leads to philosophically rich and practically relevant questions of ethics – for example, when do we stop providing life-sustaining care? In the field of bioethics and beyond, there is high demand for discussion on this topic.
There has been controversy over defining death since the 1650’s — when a woman named Anne Greene woke up after being hanged. It wasn’t until the 1980’s that a consensus definition of death was first identified. Here is a brief history:
1950s
Widespread availability of ventilators led to the identification of a state described as death of the neurological system.
1960s
Advances in organ transplantation foster discussion on the ethics of defining death.
A committee at Harvard Medical School examined the definition of Brain Death. They created a definition of “Irreversible Coma,” which focused on loss of neurological function.
1980s
The 1980 Uniform Determination of Death Act (UDDA) provided a legal basis for clinically determining death as: an individual who has sustained either 1) irreversible cessation of circulatory and respiratory functions OR 2) irreversible cessation of functions of the entire brain.
1981: President’s Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research report. Findings are centered on questions of functioning of the organism as a whole and the brain’s role in coordinating it.
1990s-2000s
Clinicians arrive at general agreement that a patient in a state of coma or unresponsiveness, without brainstem reflexes and who fails an apnea test is dead by neurologic criteria. Largely it is accepted that “brain death is death” but there is not complete consensus.
2010-late
2013: Case of Jahi McMath. A 13-year old girl was declared “brain dead” in California, and a death certificate was issued. However, the family fought to have her maintained on life support. They moved to New Jersey, the only state which recognized objections to brain death, and the “brain dead” declaration was reversed. Jahi lived there for 4 years before passing away. This famous case caused people to reconsider the concept of brain death.
2020s:
Recent innovations in heart transplantation technology will likely challenge the acceptance of the Dead Donor Rule (DDR) which requires that an individual is clinically declared dead before vital organs are removed for transplantation.
2021: Assembly of the Determination of Death Committee, tasked with updating the Uniform Determination of Death Act (UDDA). Duke faculty (and founding director of Science & Society) Nita Farahany, is involved with this process.
What ethical issues and practical questions challenging Death by Neurologic Criteria (DNC) today? Dr. Malek shared the following case.
Following a tragic car accident, Ms. Jones, a 20-year-old college student, was brought to the hospital, having suffered significant anoxic brain injury. The medical team determined that she met criteria for DNC. However, her family refused to allow for further testing. Several days passed. Ms. Jones was maintained on life support, during which she did not show signs of improvement. After several difficult conversations, the family consented for assessment and Ms. Jones was declared dead — using the criteria associated with DNC.
What is the proper amount of time to continue life-sustaining treatment if a physician suspects the patient will never recover?
Although this may sound like an uncommon occurrence, nearly half of neurologists have been asked to continue neurologic support for patients that may meet criteria for DNC.
Obligating life support for patients suspected of meeting DNC, either through the family’s refusal for testing or by direct request, would likely result in ethical harms such as violation of the dignity of decedent, unjustly using scarce resources, or causing moral distress in caregivers.
However, it may be permissible to maintain life support in these situations. Dr. Malek says that we do not yet have a good ethical framework for this. Reasonable accommodations that are in line with professional guidelines probably have minimal impact, and might provide some psychosocial benefits to families.
Is consent required to test for DNC? Should it be?
These are extremely difficult questions, and there is continuing controversy over what the correct answers should be. Dr. Malek advises medical experts to work with healthcare administrators to develop clear institutional policies.
Post by Victoria Wilson, 2023 MA student in Bioethics & Science Policy
Black-capped chickadees have an incredible ability to remember where they’ve cached food in their environments. They are also small, fast, and able to fly.
So how exactly can a neuroscientist interested in their memories conduct studies on their brains? Dmitriy Aronov, Ph.D., a neuroscientist at the Zuckerman Mind Brain Behavior Institute at Columbia University, visited Duke recently to talk about chickadee memory and the practicalities of studying wild birds in a lab.
Black-capped chickadees, like many other bird species, often store food in hiding places like tree crevices. This behavior is called caching, and the ability to hide food in dozens of places and then relocate it later represents an impressive feat of memory. “The bird doesn’t get to experience this event happening over and over again,” Aronov says. It must instantly form a memory while caching the food, a process that relies on episodic memory. Episodic memory involves recalling specific experiences from the past, and black-capped chickadees are “champions of episodic memory.”
They have to remember not just the location of cached food but also other features of each hiding place, and they often have only moments to memorize all that information before moving on. According to Aronov, individual birds are known to cache up to 5,000 food items per day! But how do they do it?
Chickadees, like humans, rely on the brain’s hippocampus to form episodic memories, and the hippocampus is considerably bigger in food-caching birds than in birds of similar size that aren’t known to cache food. Aronov and his team wanted to investigate how neural activity represents the formation and retrieval of episodic memories in black-capped chickadees.
Step one: find a creative way to study food-caching in a laboratory setting. Marissa Applegate, a graduate student in Aronov’s lab, helped design a caching arena “optimized for chickadee ergonomics,” Aronov says. The arenas included crevices covered by opaque flaps that the chickadees could open with their toes or beaks and cache food in. The chickadees didn’t need any special training to cache food in the arena, Aronov says. They naturally explore crevices and cache surplus food inside.
Once a flap closed over a piece of cached food (sunflower seeds), the bird could no longer see inside—but the floor of each crevice was transparent, and a camera aimed at the arena from below allowed scientists to see exactly where birds were caching seeds. Meanwhile, a microdrive attached to the birds’ tiny heads and connected to a cable enabled live monitoring of their brain activity, down to the scale of individual neurons.
An artistic rendering of one of the cache sites in an arena. “Arenas in my lab have between 64 and 128 of these sites,” Aronov says. Drawing by Julia Kuhl.
Through a series of experiments, Aronov and his team discovered that “the act of caching has a profound effect on hippocampal activity,” with some neurons becoming more active during caching and others being suppressed. About 35% percent of neurons that are active during caching are consistently either enhanced or suppressed during caching—regardless of which site a bird is visiting. But the remaining 65% of variance is site-specific: “every cache is represented by a unique pattern of this excess activity in the hippocampus,” a pattern that holds true even when two sites are just five centimeters apart—close enough for a bird to reach from one to another.
Chickadees could hide food in any of the sites for retrieval at a future time. The delay period between the caching phase (when chickadees could store surplus food in the cache sites) and the retrieval phase (when chickadees were placed back in the arena and allowed to retrieve food they had cached earlier) ranged from a few minutes to an hour. When a bird returned to a cache to retrieve food, the same barcode-like pattern of neural activity reappeared in its brain. That pattern “represents a particular experience in a bird’s life” that is then “reactivated” at a later time.
Aronov said that in addition to caching and retrieving food, birds often “check” caching sites, both before and after storing food in them. Of course, as soon as a bird opens one of the flaps, it can see whether or not there’s food inside. Therefore, measuring a bird’s brain activity after it has lifted a flap makes it impossible to tell whether any changes in brain activity when it checks a site are due to memory or just vision. So the researchers looked specifically at neural activity when the bird first touched a flap—before it had time to open it and see what was inside. That brain activity, as it turns out, starts changing hundreds of milliseconds before the bird can actually see the food, a finding that provides strong evidence for memory.
What about when the chickadees checked empty caches? Were they making a memory error, or were they intentionally checking an empty site—even knowing it was empty—for their own mysterious reasons? On a trial-by-trial basis, it’s impossible to know, but “statistically, we have to invoke memory in order to explain their behavior,” he said.
A single moment of caching, Aronov says, is enough to create a new, lasting, and site-specific pattern. The implications of that are amazing. Chickadees can store thousands of moments across thousands of locations and then retrieve those memories at will whenever they need extra food.
It’s still unclear how the retrieval process works. From Aronov’s study, we know that chickadees can reactivate site-specific brain activity patterns when they see one of their caches (even when they haven’t yet seen what’s inside). But let’s say a chickadee has stored a seed in the bark of a particular tree. Does it need to see that tree in order to remember its cache site there? Or can it be going about its business on the other side of the forest, suddenly decide that it’s hungry for a seed, and then visualize the location of its nearest cache without actually being there? Scientists aren’t sure.
Duke biology professor Paul Manos, Ph.D., looking at peat moss with Wild Ones members Gurnoor and Dhruv.
The Wild Ones club recently visited the Duke Forest with biology professor Paul Manos, Ph.D., and herpetology professor Ron Grunwald, Ph.D., to look for salamander eggs and other early spring delights.
It was warm and sunny, and wildflowers sprouted up alongside the trail, but most of the trees were still bare. “It’s kind of nice to look in a forest without any leaves,” says Manos. “They get in the way a lot.” We examined winged elm and shagbark hickory at the trailhead, then windflower and bluets right beside the path. Many early spring wildflowers take advantage of the higher levels of sunlight that reach the forest floor before trees develop leaves.
A shagbark hickory tree in the Duke Forest. “Shagbark” refers to the peeling strips on the trunk. The word “hickory,” meanwhile, comes from an Algonquin word for both the tree and a food made from pounded hickory nuts.
Manos was delighted to find a patch of sphagnum moss beside the trail. He says sphagnum, also known as peat moss, is usually found in higher latitudes, like the United Kingdom and Canada, where it grows in huge fields known as moorlands or quaking bogs.
When we reached a small pond, Grunwald swept a long-handled net through the water and leaf litter and pulled out a gelatinous glob that promptly became a highlight of my week/month/year: spotted salamander eggs. I don’t know what the rest of you spent your childhoods doing, but I spent a good portion of mine looking for frog eggs (and sometimes finding them) and wanting to find salamander eggs (and never finding them). But here they were, in front of me, tinted green with algae and glinting in the sunlight and close enough to touch.
Bluets are members of the coffee family, which Manos says is “known for having a lot of chemical diversity.” Many of the members of that family grow in the tropics, but some, like this bluet, live in more temperate regions.
This strikes me as an appropriate retort to many unrelated things. Calculus test? Yeah, okay, but I saw salamander eggs. The grosbeaks that Wild Ones went looking for two weeks ago are still thwarting me? Yes, and I still haven’t gotten over it. However: salamander eggs.
Sphagnum moss. It is wonderfully moist and spongy. Photo by Lydia Cox, one of the student leaders of Wild Ones.
The egg mass was less firm and less slimy than I expected. It felt remarkably similar to jelly. “This gel,” Manos says, “apparently doesn’t allow oxygen to move through it very well,” but the developing spotted salamander larvae need oxygen. The solution is ingenious: a partnership with green algae. A species of algae grows on the egg masses and penetrates individual eggs, and eggs with more algae grow and develop faster.
The algae are photosynthetic, creating carbon and oxygen products from carbon dioxide gas and sunlight. That process likely provides supplemental oxygen to the salamander embryos, and one study found that the salamanders also absorb carbon produced by the algae’s photosynthesis.
Herpetology professor Ron Grunwald with spotted salamander eggs.
That carbon fixation is the first known example of carbon transfer from algae to a vertebrate host, though similar partnerships have been found in invertebrates, and the authors of the study speculate that similar processes may be occurring in other amphibians as well.
The particular species of algae that grows on spotted salamander eggs is in the Oophila, which according to Manos means “egg lover.” The partnership, however, is temporary. “It’s a very short-lived, ephemeral story,” Manos says.
“This is the best day of my life,” says Michelle, a Wild Ones member, while holding spotted salamander eggs. Comments from other students included “This feels weird,” “That is a sublime experience,” and “Nature’s fidget.”
In addition to the spotted salamander eggs, Grunwald also found a marbled salamander larva. Marbled salamanders and spotted salamanders are in the same genus, but they have different approaches to breeding. Marbled salamanders, Grunwald explains, lay their eggs in the fall “where they think a pond is going to be” instead of waiting for ephemeral pools to develop in spring. How do they decide where to lay eggs if the pond isn’t even there yet? Scientists aren’t sure, but salamanders “live in a chemical world,” Grunwald says, relying on taste and chemical signals.
Spotted salamander eggs and a marbled salamander larva, temporarily held in a plastic bag for viewing purposes. Photo by Adam Kosinski, Wild Ones co-president.
Since marbled salamanders laid their eggs last fall, their larvae have had time to hatch and start developing, though they aren’t yet adults. Spotted salamanders, meanwhile, don’t breed until spring—when the ponds actually exist—so their eggs haven’t yet hatched. For the larvae of both species, developing in small, temporary ponds helps protect them from large predators like fish.
Both marbled and spotted salamanders are in a genus sometimes called mole salamanders because they live underground when they’re not breeding. “There’s an entire city underground here of burrows and holes and crevices,” Grunwald says, a “whole porous network of spaces.” The mole salamanders can shelter underground, but they can’t travel far without coming back to the surface. “It’s not a highway,” Grunwald says.
I would like to know what it is like to be a mole salamander, navigating by taste and smell and spending much of the year in small spaces underground.
Sam, a Wild Ones member, releasing the eggs back into the pond.
Before we left the forest, we went searching for lycophytes, an ancient lineage of plants that first evolved hundreds of millions of years ago. “In the Carboniferous Period 350 million years ago, these guys ruled,” Manos says. The lycophytes we saw in the Duke Forest were tiny, bright green sprigs in a small stream, but their ancestors were trees. Those ancient lycophyte trees are “responsible for all of the coal that we use,” says Manos. “The transformation of their organic material via millions of years of heat and pressure to metamorphic carbonized rock is the definition of coal.”
Quillwort, a modern-day descendant of ancient trees.
The lycophytes in the stream are members of the Isoetes genus, also known as quillworts. They look and feel much like grasses, but they are only distant relatives of true grasses. Grasses are flowering plants, while quillworts are lycophytes. Flowering plants and lycophytes diverged hundreds of millions of years ago. Lycophytes use spores to reproduce and have a life cycle similar to ferns. Even their leaves are anatomically and evolutionarily different from the leaves of flowering plants; lycophytes use “their own approach to making leaves,” according to Manos.
The Wild Ones, a student organization focused on enjoying and learning about nature, recently went to Flat River Waterfowl Compound to look for birds and my personal nemesis.
I have a nemesis (a bird that defies my searching). Actually, Ihaveseveral, but I have been preoccupied with this particular nemesis for months.
I have seen an evening grosbeak exactly once, in a zoo, which emphatically does not count. For years, I have been fixated on-and-off (mostly on) with the possibility of seeing one in the wild.
They have thick, conical beaks. The males are sunset-colored. (But good luck finding one at sunset, even though the first recorded sighting supposedly happened at twilight, hence their name.) I daydream about flocks of them descending on my bird feeders at home or wandering onto Duke’s campus. That hasn’t happened yet (unless it has happened while I have not been watching, an excruciating possibility I will simply have to live with).
Evening grosbeaks usually live in Canada and the northern U.S., but they are known to irrupt into areas farther south. Irruptions often occur in response to lower supplies of seeds and cones in a bird’s typical range, making it possible to predict bird irruptions, at least if you’re the famous finch forecaster. (Fun fact: “irrupt” literally means “break into,” whereas “erupt” means “break out.”)
Breaking news: The grosbeaks are in Durham, and they have been since December. I will wait while you perform any necessary reactions, including screaming, jumping up and down in delight, charging outside because you simply have to go find them right now, or telling me I must be mistaken.
I am not mistaken. There is a flock of evening grosbeaks overwintering at Flat River Impoundment, 11.8 miles from Duke University. I know this because I get hourly rare bird alerts by email, and I have been receiving emails about evening grosbeaks nearly every day for almost three months. Put another way, evening grosbeaks have been actively and no doubt intentionally taunting me for weeks on end.
Adam Kosinski, Wild Ones co-president, with binoculars.
Wild Ones, a student organization I’m involved with, had been thinking of organizing a birding trip. For reasons I will not even attempt to deny, I suggested Flat River Waterfowl Impoundment. Last Sunday, seven undergraduates drove there, armed with field guides and binoculars and visions of evening grosbeaks bursting into sight (okay, maybe that was just me).
Flat River Waterfowl Impoundment. Photo by Adam Kosinski.
The morning was chilly but sunny. Flat River is a gorgeous, swampy place full of small ponds and stretches of long grass edged with trees. As soon as we got there, we were serenaded with birdsong: the high, musical trill of pine warblers, the haunting coo of mourning doves, lilting Carolina wren songs, and squeaky-dog-toy brown-headed nuthatch calls.
Photo by Adam Kosinski.
It wasn’t long before people got to experience the frustrating side of birding. We were admiring a sparrow in a ditch, trying to guess its identity. Someone pulled out a field guide and flipped through the sparrow section only to turn back to the bird and find it gone. Birds can fly. But fortunately, we’d collectively noticed enough field marks to feel reasonably confident identifying it as a swamp sparrow.
A white-throated sparrow, one of several that was feeding on the buds of this tree. Note the white throat and yellow lores. Photo by Lydia Cox, Wild Ones member. (We are not related, if you’re wondering.)
We found two other sparrow species later: song sparrows and white-throated sparrows. Sparrows tend to be small, brownish, and streaky, but certain features can help distinguish some of the common species around here. I’m personally not very familiar with the swamp sparrow, but it has a rusty cap and gray face. The song sparrow has brown stripes on its head, extensive streaking on its underside, and a dark spot on its breast. The white-throated sparrow has striking black-and-white stripes on the top of its head, yellow lores on its face (the spot in front of the eye), and yes, a white throat. (Just don’t rely too much on bird names for identification. Red-bellied woodpeckers definitely have red heads but usually only have red bellies if you’re rather imaginative, but beware—they’re still red-bellied, not red-headed woodpeckers. Meanwhile, there are dozens of warblers with yellow on them, but only one of them is a yellow warbler. Nashville warblers only pass through Nashville during migration, and American robins aren’t robins at all.)
A Cooper’s hawk with prey between its talons. Note the gray wings, the red barring on the bird’s underside, the dark bands on its tail, and the red eye. Photo by Lydia Cox.
We saw Carolina chickadees flitting through trees, an Eastern phoebe doing its characteristic tail-wagging, and a Cooper’s hawk feeding on prey. Then, thrillingly, we spotted a bald eagle soaring through the sky. The bald eagle, America’s national bird since 1782, was in danger of extinction for years, largely due to the insecticide DDT, which made their eggs so thin that even being incubated by their parents could make them crack. However, the bald eagle was removed from the endangered species list in 2007, and populations have continued to increase.
A bald eagle in flight. Photo by Lydia Cox.
Not long after the eagle sighting, we saw another flying raptor: an osprey. In fact, it must have been a good day for raptors because by the end of our trip we had recorded one osprey, two Cooper’s hawks, three bald eagles, and two red-tailed hawks.
We also saw a lot of birders—perhaps two dozen others, maybe more, not counting our own group. Each time we passed a group going in the opposite direction, I asked them if they’d found the grosbeaks.
A bald eagle nest. Photo taken with my phone through my binoculars, a technique that is slowly teaching me a modicum of patience.
I think everyone I asked had seen them, and they were all eager to point us in the right direction. Birders like to use landmarks like “by the eagles’ nest” and “the fifth pine on the right” and “past the crossbills.” We found the eagles’ nest, with help from some of the local birders. We think we found the fifth pine on the right, but there were a lot of pines there, so we’re not sure.
We did not find the red crossbills, another irruptive bird species overwintering here this year. (Crossbills are aptly named. The tips of their mandibles really do cross, which helps them access seeds inside cones.)
Red crossbills, another irruptive bird species, have also been overwintering at Flat River Waterfowl Impoundment, but Wild Ones did not see them. “Red Crossbills (Male)” by Elaine R. Wilson, www.naturespicsonline.com is licensed under CC BY-SA 3.0.
We found the spot where the evening grosbeaks had most recently been seen — just twenty minutes before we got there, according to the people we were talking to. We waited. We scrutinized the pine trees. We watched red-tailed hawks and bald eagles circle high above us. We admired the eagles’ nest, a huge collection of sticks high in a pine tree.
Adam Kosinski and Abby Saks, making sure there were no birds hiding underwater. (They were actually looking at interesting water creatures like crayfish and tadpoles.)
Would you like to guess what we did not find? My nemesis. Because the evening grosbeaks have devious minds and clearly flew all the way to Durham with the sole intent of hiding from me, dodging me, flying away as soon as I approached, and flying back again as soon as I was gone. (No, really. Other people reported them at Flat River that same day, both before and after our trip there.)
From left: Ethan Rehder, Barron Brothers, Sophie Cox, Gurnoor Majhail (Wild Ones co-president), and Lydia Cox. Photo by Adam Kosinski.
Birding can be intensely frustrating. It can plant images in your mind that will haunt you and taunt you for the rest of your life. Like, for instance, the tiny blue bird I caught a brief glimpse of in the trees one early morning in Yellowstone. For years, I wondered if it could have been a cerulean warbler, but cerulean warblers don’t live in the western U.S. Or let’s talk about the green bird—yes, I swear it was green; no, I can’t prove it—that came to my bird feeders several years ago and never came back. Not while I was watching, anyway. The only thing I can think of for that one is a female painted bunting, but painted buntings aren’t usually in upstate South Carolina. (If my local volunteer eBird reviewer in South Carolina ever happens to read this, I promise I won’t report either of those mystery sightings to eBird.) Or, of course, the evening grosbeaks that flew away twenty minutes before we arrived.
Birding can also be thrilling, meditative, and by all accounts wonderful. Yes, that little blue bird in Yellowstone and the maybe-green one in my backyard are branded in my memory, as are countless more moments of maybe and almost and what if? I will never know what they were. I will probably never get over it.
But there are other moments that stick in my mind just as clearly. The bald eagle soaring above us on this Wild Ones trip. The black-capped chickadee that landed on my finger years ago while my brother and I rested our hands on a bird feeder and waited to see what would happen. My first glimpse of a black-throated blue warbler (I am so proud of whoever named that bird species), chasing an equally tiny Carolina chickadee in my backyard.
The Cape May warbler I saw with a close friend in a small field covered in purple wildflowers. The first time I heard the loud, ringing Teacher-teacher-teacher! song of the ovenbird. A blackpoll warbler, the first I’d ever seen, in a grove of trees in a swampy field that only birders seem to find reason to visit.
The moment two Carolina wrens took food from my hand for the first time. Prothonotary warblers (another nemesis bird) practically dripping from the trees on a rainy, buggy hike along a boardwalk. The downy woodpecker that landed on my gloved hand, apparently too impatient to wait for me to finish what I was doing with the suet feeder, and pecked at the suet with that sharp beak, her black tongue flicking in and out, her talons clinging to me with a trust that brought tears to my eyes.
Birding can change you. It can make your world come alive in a whole new way. It can make traveling somewhere new feel all the more magical — a new soundscape, new flashes of colors and patterns, a new set of beings that make a place what it is. In the same way, birding can make home feel all the more like home. Even when I can’t name all the birds that are making noise in my yard, there is a familiarity to their collective symphony, a comforting sense of “You are here.” I encourage you to watch and listen to birds, too, to join the quasi-cult that birding can be, to trek through somewhere wet and dark when the sky is just beginning to lighten—or to simply step outside, wherever you are, and listen and watch and wait right here and right now. You don’t even need to know their names (though once you start, good luck stopping). And you certainly don’t need a nemesis bird. In fact, your birding experience will be calmer without one. But that might not be up to you, in the end. Nemesis birds have minds of their own.
