Imagine driving down a narrow dirt road, then turning between pine trees onto an even narrower track that ends in a grassy field. Open the gate at the edge of the field and you see a grove of ten-foot high Ginkgo biloba trees. A dozen of the ginkgos are enclosed in personalized plastic greenhouses. Nearby stand fat, frosty, metal tanks of liquid carbon dioxide, which, warmed and turned to gas, is then vented through a complex array of tubes and dials to the air inside each greenhouse.
This ginkgo grove, located at the Smithsonian Environmental Research Center in Edgewater, Maryland, is part of an experiment called Fossil Atmospheres. It’s designed to test how the concentration of carbon dioxide affects the growth of these so-called “living fossils.” Why are we doing this? We want to use fossil ginkgo leaves to figure out how much carbon dioxide was in the atmosphere during periods of globally warm climate millions of years ago. This, in turn, should help us understand the relationship between carbon dioxide and climate. But we need your help.
Here’s how it works. Almost all plants make their food through photosynthesis – the process that uses solar energy to convert carbon dioxide and water to sugars used for growth. Carbon dioxide enters leaves through microscopic pores called stomata, but plants can’t help but lose precious water vapor through the same holes. Virtually every plant has to balance the benefit of rapid uptake of carbon dioxide, which allows faster growth, with the danger of wilting from rapid loss of water. This balance requires just the right number of stomata.
Our prediction? Higher concentrations of carbon dioxide will cause leaves to develop fewer of the tiny pores. What we want to know is how few stomata ginkgo plants make when they grow in air containing a lot of carbon dioxide.
Back to our little ginkgo grove. Except for the high carbon dioxide levels, our ginkgos are growing out in the wild. The greenhouses are open at the top, exposing the trees to cold, wind, rain, harsh sunshine, heat and humidity. They even have to suffer being munched on by insects, though lucky for them few species are interested in eating their leaves. Growing the trees outdoors is important for our experiment, because we want to compare the leaves of our trees to fossils from millions of years ago, and those ancient trees also had to survive the elements. However, this does leave the whole experimental apparatus exposed to the elements. We paid the price for this last winter when a cold front with strong winds destroyed much of the ductwork we had built to deliver the CO2 to the greenhouses. Nobody said this was going to be easy!
There are a total of 15 trees in our experiment. Six trees are growing at 400 parts per million (ppm) of carbon dioxide - the amount in the atmosphere today. (It was only 280 ppm in 1820!) Three trees are growing at 600 ppm, which is the concentration carbon dioxide might reach by the year 2100 if the rate of emissions from human activities isn’t curtailed. Three trees are growing at 800 ppm and three more at 1000 ppm, conditions designed to mimic the distant past when the climate was so warm there were no polar ice caps.
When the daylight wanes in November and December, and the temperatures start to freeze here in Maryland, ginkgos drop their leaves in spectacular fashion. Over a span of a couple of weeks they turn a lovely yellow color. Then, almost overnight, all the leaves fall, creating beautiful aprons of yellow on the ground. In the spring, the trees sprout fresh new green leaves. These new leaves have integrated the atmospheric conditions that the tree experienced the previous year. This is the second year of the Fossil Atmospheres experiment, and we will need to run the experiment for several more years to come. It will take time for the ginkgo trees to become accustomed to their new carbon dioxide levels. We expect this year’s leaves will have fewer stomata than last year’s, with the smallest numbers on the plants growing at the highest levels of carbon dioxide.
If we can work out the relationship between concentration of carbon dioxide and the number of stomata on the experimental ginkgo leaves, we could reverse the relationship and use the number of stomata on a fossil leaf to calculate the amount of carbon dioxide in the air when that leaf was alive. This is precisely what we are doing. In addition to counting the number of stomatal pores in a small rectangle of the same size on each leaf, we also count the number of regular cells so that we can calculate a simple ratio called stomatal index (# stomata/# regular cells + # stomata). Stomatal index seems to respond more reliably to carbon dioxide levels than simple stomatal number. If we can characterize the relationship between carbon dioxide and stomatal index accurately, we should be able to pick up a fossil ginkgo leaf and know the composition of the air in which it grew.
One of the most exciting things about ginkgos is that they fossilize exceptionally well. Some of our fossils, millions of years old, can literally be lifted off the rock with our fingertips and held up to the light to see their veins. The cellular structure of the leaves is also well preserved. This faithful preservation means we can take a 60 million year old ginkgo leaf and count the cells in the same way we would on a leaf from one of our experimental trees. The abundance of well-preserved ginkgo fossils can provide a detailed record of how carbon dioxide in the atmosphere has changed with changing climate over millions of years.
This is where you as a citizen scientist can play a part in our research. We have thousands of microscope images of the surfaces of ginkgo leaves, where you can see the cells of each leaf in exquisite detail. We need to know how many of each different type of cell are present on each leaf to calculate the stomatal index. Having lots of people collect this data from each image is a great advantage to the research team because it means we can complete the project in a reasonable amount of time. More importantly, sometimes we debate how to properly count the cells, and having many opinions will help us come to a consensus on the right answer. Debate can be healthy!
We hope that joining the project will be beneficial for you as citizen scientists too. You are collecting the primary data, which means you’re participating in actual Smithsonian research. You can get a sense of how the scientific process really works, and we will keep you updated with results as the project progresses. We will be watching everyone’s progress, and actively communicating with contributors to answer any questions about data collection or the science behind the project. It will be like having your very own personal scientists!
Ginkgo biloba, or the ‘maidenhair tree’, is the last surviving species of an ancient lineage that first appeared before the dinosaurs, survived three major mass extinction events, and looks virtually the same now as it did in the ancient forests of the Cretaceous, 80 million years ago. Now we hope to use this ultimate survivor to help answer an important question about the future - as we humans add carbon dioxide to the atmosphere, how warm will the planet get? This question can be answered if we can reconstruct past changes in carbon dioxide and climate. The past will help give us the knowledge we need to anticipate the future!
Rich Barclay is the lead scientist on the Fossil Atmospheres experiment and Laura Soul is coordinating the citizen science effort. Both are at the Smithsonian’s National Museum of Natural History in Washington, D.C.
Join the project at: https://www.zooniverse.org/projects/laurasoul/fossil-atmospheres
The botanical specimens housed in the U.S. National Herbarium (USNH) at the National Museum of Natural History have been assembled over the course of several centuries and the collection continues to grow today. Currently, the herbarium contains over 5 million plant specimens and serves as an encyclopedia of the Earth’s flora. These specimens are irreplaceable sources of information regarding the diversity of species and the habitats they come from. They play a critical role in taxonomy, systematics, anatomy, morphology, ethnobiology, paleobiology, and conservation biology. The specimens can be used to discover and confirm the identity of a species new to science. They provide locality data for conservation assessments. They can document the effects of climate change on flowering phenology. They also provide material for DNA analysis and conservation genetics.
For world history buffs, these specimens provide a peek into the past, not only into the expeditions in which the plant was collected, but every so often they document major social events. The clues are usually found on annotation labels attached to the herbarium sheet. Most often these annotation labels tell us of the changing understanding of which species you’re holding. But every now and then you get a glimpse into history.
Take for instance USNH specimen 2318036 pictured above. The preserved plant attached to the sheet is a species in the bellflower family (Campanulaceae) named Cyananthus spathulifolius (which has now been renamed Cyananthus macrocalyx subspecies spathulifolius). The collection label, which details the collection event, tells us that it was collected on July 27, 1936, from the rocky hillslopes of Tibet at 14,000 feet by the English/Scottish team of explorers, Frank Ludlow and George Sherriff. The sheet has a stamp telling us that it currently resides in the U.S. National Herbarium. The collection label indicates that it was previously held in the herbarium of the British Museum (“Ex Herbario Musei Britannici”).
The annotation label on this sheet makes this specimen unique. Annotation labels are attached to specimens at a later date with new or additional information about the specimen. The label on this specimen reads “Sheet damaged by enemy action at British Museum (Natural History) on 10 September 1940.” During World War II, German forces targeted London, and London’s Natural History Museum was badly damaged when 28 bombs landed on or near the museum during the month of September 1940. British scientists did their best to prepare for war by protecting the museum’s specimens. Earlier, after war was declared, collections from a number of research departments such as geology and entomology were removed from the museum and sent to private homes in the countryside. Sadly, many botanical specimens and books that hadn’t been moved yet were either harmed or destroyed when two bombs went through the roof of the botany department.
The bellflower specimen collected by Ludlow & Sherriff was damaged but survived. In 1954, the specimen was sent to the U.S. National Herbarium as part of an exchange of specimens with the Natural History Museum of London. Museums and herbaria around the world are steeped in a history of sharing and collaboration, and they have a long history of collection exchange. By moving specimens around the world, exchanges allow herbaria to expand the geographic and taxonomic ranges of their collections. Duplicate specimens, those collected from the same plant or population by the same collector at the same time, are often used in exchanges. By sending duplicates to a number of herbaria, the specimen and the valuable data associated with it are insured against loss or damage that may occur at one particular location.
The Natural History Museum of London wasn’t the only institution to suffer greatly during World War II. The herbarium of the Botanical Museum Berlin-Dahlem in Germany, which at the time housed 4 million specimens, was destroyed in a bombing raid in March 1943. While approximately 500,000 specimens were saved (the collections of German botanist Carl Willdenow were safe-guarded in a bank vault), the majority perished. A similar fate befell the herbarium of the Philippine National Museum in Manila, which was burned down a day before the liberation of Manila in 1946. Fortunately, before the war began, duplicates of historic Philippine plant specimens had been sent on exchange to the U.S. National Herbarium and other American herbaria.
More recent examples of museum damage and the loss of specimens and artifacts include the destruction and looting of museums in the Middle East after the political uprisings of 2010 and the destruction of Gabon’s National Herbarium by arsonists during post-election riots in 2016. Natural disasters have destroyed natural history collections as well, such as the devastating San Francisco earthquake on the California Academy of Sciences in 1906 and Hurricane Katrina’s flooding of the herbarium of the Gulf Coast Research Laboratory in Ocean Springs, Mississippi in 2005.
Man-made and natural disasters aren’t the only way specimens might meet an unfortunate fate. While the exchange and loan of botanical specimens may be considered a safe-guard, sending material through the mail carries an inherent risk. During transport, fragile specimens may get lost or suffer damage. A worst case scenario took place recently when type specimens dating back to the mid-1800s were destroyed while in transit from the French National Museum of Natural History in Paris to Queensland's herbarium in Brisbane, Australia.
As a conservation biologist, I value specimens for the data written on the labels. I use the data to assess the conservation status of the world’s flora. Irreplaceable plant specimens may represent the last bit of evidence that a species now extinct had existed on Earth. For example, my colleagues and I recently completed a conservation assessment of 263 endemic plant species from the Lesser Antilles. Two montane species that we assessed, a false pimpernel (Lindernia brucei) and a brushholly (Xylosma serrata) are both known only from single volcanic sites on the islands of St Vincent and Montserrat, respectively. Neither species has been recollected since the most recent volcanic eruptions of 1979 and 1995 on these islands. With the only known populations of these two species destroyed by volcanic flow, both the false pimpernel and the brushholly may now be extinct. What little we know about these plants is preserved on a few herbarium sheets.
The U.S. National Herbarium is preserving its rich specimen data by digitizing its entire collections. Working its way through 5 million specimens, the digitizing team has recently imaged and databased its one millionth specimen. Digitization benefits museum scientists by creating a detailed inventory of plants and records at each herbarium. Researchers can access specimens from all over the world right from their desks without the underlying risk of mailing specimens.
While digitized records of specimens are a great way to preserve data, the specimens themselves are still necessary to researchers. Only the specimen, and not a digitized photograph, provides material for DNA analysis, pollen for taxonomic and pollination studies, and leaves for chemical analysis. Moreover, online data may not be permanent, as online servers are vulnerable to computer viruses or hacking and data could be intentionally or accidentally removed or deleted. Digitizing the records of our herbarium specimens is important for expanding our scientific reach, but safely securing museum specimens is essential for current and future botanical research.
On April 22, 1970, millions of people heard the call to protect our planet from industrial pollution, deforestation, and other destructive effects of increasing human pressure on Earth’s natural resources. Huge public demonstrations of environmental awareness and activism marked the first Earth day celebration across the U.S. Before the end of the year, the Environmental Protection Agency was established and the Clean Air, Clean Water, and Endangered Species Acts passed. By 1990, Earth Day was observed by 200 million people on all seven continents, united in a global mission for a healthier planet. Last year, on Earth Day in 2016, the U.S. and more than 100 other nations signed the Paris Agreement in a landmark move to lower greenhouse gas emissions and reduce climate change risks and impacts around the world.
On Earth Day in 2017, scientists will come together as never before to raise environmental awareness and foster better stewardship of our rapidly changing planet. In support of science as an essential evidence-based voice in the public interest, activities on Earth Day will include a March for Science on the National Mall in Washington, D.C. A few steps away, the Smithsonian Conservation Commons will present the first Earth Optimism Summit--a “master class in saving the planet” that will gather conservation scientists and supporters to share success, inspire hope, and motivate action.
These events will convene communities that see the human hand in forces that shape Earth’s future and offer solutions informed by knowledge and understanding of those forces. Yet, outside these communities, many people still fail to recognize the relevance of environmental issues to human health and well-being. Why should we care about a warmer global average temperature, while thousands of people are getting sick from Zika virus, yellow fever, and other infectious diseases? And why should we care about Zika virus, yellow fever, or other infectious diseases if they don’t occur where we live?
We are now living in a highly connected world. Human health threats anywhere can have impacts everywhere. However, we can only be as healthy as the global ecosystem in which we live and on which we depend. This is the main message of Planetary Health--an evolving discipline of enormous scope, where human health is inseparable from the state of Earth systems. By integrating natural and social sciences in a broader conceptualization of public health, Planetary Health requires a new community of practice and common source of knowledge about human causes and effects of global environmental change. Communicating across scholarly and professional boundaries is an important step to this approach, and one of the major challenges to its development.
On April 4, we published an invited commentary in the Journal of the American Medical Association (JAMA) about Congenital Zika Syndrome. We argued that the pan-epidemic spread of Zika virus and other zoonotic viruses such as Ebola, yellow fever, and avian influenza, are related to industrialization, urbanization, globalization, and other broad-scale human impacts on the environment. With Zika virus, for example, global warming from greenhouse gas emissions can extend the geographic range of mosquitos and the pathogens they carry. People infected with these pathogens can spread them widely and quickly in densely populated urban areas and via global air travel – which can take a virus anywhere in the world within 24 hours. Among people who lack adequate health care, sanitation, or food supplies, diseases can occur and spread unchecked. In the Age of Humans – the “Anthropocene” epoch of human-induced changes to the global ecosystem – we see an increased risk for more pan-epidemics in the 21st century that could be addressed through a holistic framework of Planetary Health.
While Planetary Health is not a novel concept, its economic linkages, policy-focused aims, and whole-planet approach are promising for addressing human health challenges in a rapidly changing global environment. To broaden our thinking in connecting the health of the planet with our own, we are bringing together a wide variety of researchers, educators, and other professionals in a Planetary Health seminar at the Smithsonian’s National Museum of Natural History (NMNH). From February until June 2017, we aim to increase communication across organizations and institutions through a monthly series of focused panel discussions on a specific topic of Planetary Health such as pollution, globalization, biodiversity, oceans, and climate, and explore the possibilities of this growing field. We will present our findings from the course at the inaugural Planetary Health/GeoHealth annual meeting at Harvard Medical School in Cambridge, MA on April 29-30 in order to help fuel this community and strengthen its networks.
Planetary health is human health. We invite you to join us in celebrating Earth Day as not only a call to protect our planet, but also ourselves – and the future we share.
Did you know that the Smithsonian’s National Museum of Natural History has over 33,000 egg clutches (groups of eggs laid at the same time) in its bird egg collection? That’s more than 109,000 individual egg specimens! It is a hidden gem that rivals the fanciest Easter basket imaginable. The eggs vary in size, shape, color, and pattern and reflect the diversity of life on this planet. So, how did the collection start? And why do we have so many bird eggs?
The Smithsonian played an important role in the development of oology (the collection and study of bird eggs) as a science in the United States and supported the first eggers. Now, the term “egger” might conjure up images of teens in the night throwing eggs at a house, but I assure you it is used to describe contributors to one of science’s unique resources, museum bird egg collections.
Formally known as oologists, eggers collected bird eggs and started their own private collections in what was originally a European pastime in the 1830s. This activity migrated to the States in the mid-1800s and collecting hit its heyday around the turn of the twentieth century.
Famous eggers during this time included John James Audubon, President Franklin Delano Roosevelt, and Edward Avery McIlhenny, son of Tabasco sauce inventor, Edmund McIlhenny.
As oology’s popularity increased in the early 1900s, two groups of eggers emerged: hobbyists and oologists. While hobbyists collected for just that reason, a hobby, oologists followed strict protocol for marking and documenting their eggs as scientific specimens and published their findings. They even set up a vast trading network in the new publication “The Oologist.”
In the end, Congress passed the Migratory Bird Treaty Act in 1918 which made it illegal for just anyone to collect bird eggs or keep them without a federal permit. So, most of the vast collections were deposited in museums like the Smithsonian’s National Museum of Natural History.
Even though egg collecting is not as prevalent as it once was, the importance of the collection has not diminished. The attention to detail and superb record keeping of the early eggers proved to be very useful to scientists. In particular, they were pivotal in banning the use of DDT (Dichlorodiphenyltrichloroethane) which bolstered bald eagle, peregrine falcon, and brown pelican populations, helped farmers understand lighting for the best egg development, and contributed to countless climate change studies.
Oologists’ records and NMNH’s bird egg collection have and continue to "egg on" groundbreaking scientific research.
I see and work with this legacy every day. And, now, you can experience it for yourself. A spectacular selection of our bird eggs is on view in Objects of Wonder through 2019.
With Thanksgiving almost here, many people are looking forward to turkey, stuffing, cranberry sauce, pumpkin pie…But as a scientist who studies what people ate in the deep past - the real paleo diet – I’m bracing myself for the inevitable questions from people who want to know what’s on the menu that qualifies. If, like me, you enjoy the friendly debunking of baseless nutritional lore, here are some conversation starters for this holiday weekend.
First, some context. I study the evolution of our ancestral diets, particularly focused on the earliest meat-eating. To do that, I look at fossils of animal bones from sites with evidence that early humans and ancient carnivores had eaten them. Early humans leave butchery marks from the stone knives they used to slice meat off of bones and the rounded stones they used to bash open the bones to get at the fat- and calorie-rich marrow; carnivores leave gnawing damage and marks from their teeth. I look at these marks to find out who ate what; who got the juiciest parts of the animals? Did the early humans get there first, perhaps even hunting the herbivores, or did the carnivores munch to their satisfaction and the early humans came in afterwards and get the leftover scraps?
But back to today… one of the main tenets of the modern paleo diet movement is that we (modern humans) haven’t had enough time to evolve the capacity to efficiently and effectively digest certain foods. The focus is usually wheat (or similar grains), but can also include dairy and legumes. To that I say hogwash! There’s good archaeological evidence from residues of a wild relative of sorghum on the edges of stone tools from Mozambique that people have been processing and eating grains for over 100,000 years; plant remains from a site in Israel indicate that people sowed, harvested, and ground wheat, barley, and oats for 23,000 years. Modern populations with high-starch diets have more copies of a gene called AMY1 that causes the production of more salivary amylase (the enzyme in saliva that helps break down starch) than populations with low-starch diets. There’s even recent evidence of similar mutation in domestic dogs facilitating starch digestion dating back between 5,000-7,000 years ago - handy for a species hanging around with humans who were eating more and more starchy foods.
And digesting dairy? That’s one of my favorite examples of fast, recent human evolution. About a third of people on the planet today can digest lactose (milk sugar) after the age of weaning due to persistence of the production of the lactase enzyme. More than 6,500 years ago? Basically none. How do we know? DNA from ancient skeletons. In a geological blink of an eye, at least three independent mutations for lactase persistence arose in populations of people who were domesticating dairy animals in Africa, the Middle East, and Europe (which we know from the archaeological record of the animal fossils and 7,500-8,000 year old pottery in eastern Europe used for making dairy products like yogurt, cheese, or butter). These mutations were strongly selected for; after all, when farmers brought domesticated plants to different environments and their crops sometimes failed in these new habitats, being able to drink a clean source of protein and fat-filled fluid would have come in very handy - and could have meant the difference between surviving and, well... not.
So when you sit down to eat your Thanksgiving meal and one of your dinner companions starts to chew the fat about how the things on the table wouldn’t have been on the paleo diet, now you have a little more to talk about.