Computerized, rolling DNA motors move molecular robotics to next level

"I love the idea of using something that's innate in all of us to engineer new forms of technology," says Emory graduate student Selma Piranej, shown with a cell phone microscope set up to observe the rolling DNA-based motors.
 

By Carol Clark

Chemists integrated computer functions into rolling DNA-based motors, opening a new realm of possibilities for miniature, molecular robots. Nature Nanotechnology published the development, the first DNA-based motors that combine computational power with the ability to burn fuel and move in an intentional direction. 

“One of our big innovations, beyond getting the DNA motors to perform logic computations, is finding a way to convert that information into a simple output signal — motion or no motion,” says Selma Piranej, an Emory University PhD candidate in chemistry, and first author of the paper. “This signal can be read by anyone holding a cell phone equipped with an inexpensive magnifying attachment.”

“Selma’s breakthrough removes major roadblocks that stood in the way of making DNA computers useful and practical for a range of biomedical applications,” says Khalid Salaita, senior author of the paper and an Emory professor of chemistry at Emory University. Salaita is also on the faculty of the Wallace H. Coulter Department of Biomedical Engineering, a joint program of Georgia Tech and Emory. 

The motors can sense chemical information in their environment, process that information, and then respond accordingly, mimicking some basic properties of living cells. 

“Previous DNA computers did not have directed motion built in,” Salaita says. “But to get more sophisticated operations, you need to combine both computation and directed motion. Our DNA computers are essentially autonomous robots with sensing capabilities that determine whether they move or not.” 

The motors can be programmed to respond to a specific pathogen or DNA sequence, making them a potential technology for medical testing and diagnostics. Another key advance is that each motor can operate independently, under different programs, while deployed as a group. That opens the door for a single massive array of the micron-sized motors to carry out a variety of tasks and perform motor-to-motor communication. 

“The ability for the DNA motors to communicate with one another is a step towards producing the kind of complex, collective action generated by swarms of ants or bacteria,” Salaita says. “It could even lead to emergent properties.” 

The high speed of the rolling DNA-based motor allows a simple smart phone microscope to capture its motion through video.
 

DNA nanotechnology takes advantage of the natural affinity for the DNA bases A, G, C and T to pair up with one another. By moving around the sequence of letters on synthetic strands of DNA, scientists can get the strands to bind together in ways that create different shapes and even build functioning machines. 

The Salaita lab, a leader in biophysics and nanotechnology, developed the first rolling DNA-based motor in 2015. The device was 1,000 times faster than any other synthetic motor, fast-tracking the burgeoning field of molecular robotics. Its high speed allows a simple smart phone microscope to capture its motion through video. 

The motor’s “chassis” is a micron-sized glass sphere. Hundreds of DNA strands, or “legs” are allowed to bind to the sphere. These DNA legs are placed on a glass slide coated with the reactant RNA, the motor’s fuel. The DNA legs are drawn to the RNA, but as soon as they set foot on it they erase it through the activity of an enzyme that is bound to the DNA and destroys only RNA. As the legs bind and then release from the substrate, they keep guiding the sphere along. 

When Piranej joined the Salaita lab in 2018, she began working on a project to take the rolling motors to the next level by building in computer programming logic. 

“It’s a major goal in the biomedical field to take advantage of DNA for computation,” Piranej says. “I love the idea of using something that’s innate in all of us to engineer new forms of technology.” 

DNA is like a biological computer chip, storing vast amounts of information. The basic units of operation for DNA computation are short strands of synthetic DNA. Researchers can change the “program” of DNA by tweaking the sequences of AGTC on the strands. 

“Unlike a hard, silicon chip, DNA-based computers and motors can function in water and other liquid environments,” Salaita says. “And one of the big challenges in fabricating silicon computer chips is trying to pack more data into an ever-smaller footprint. DNA offers the potential to run many processing operations in parallel in a very small space. The density of operations you could run might even go to infinity.” 

Synthetic DNA is also biocompatible and cheap to make. “You can replicate DNA using enzymes, copying and pasting it as many times as you want,” Salaita says. “It’s virtually free.” 

Limitations remain, however, in the nascent field of DNA computation. A key hurdle is making the output of the computations easily readable. Current techniques heavily rely on tagging DNA with fluorescent molecules and then measuring the intensity of emitted light at different wavelengths. This process requires expensive, cumbersome equipment. It also limits the signals that can be read to those present in the electromagnetic spectrum. 

"Developing devices for biomedical applications is especially rewarding because it's a chance to make a big impact in people's lives," says Piranej, shown during a trip to San Franciso.

Although trained as a chemist, Piranej began learning the basics of computer science and diving into bioengineering literature to try to overcome this hurdle. She came up with the idea of using a well-known reaction in bioengineering to perform the computation and pairing it with the motion of the rolling motors. 

The reaction, known as toehold-mediated strand displacement, occurs on duplex DNA — two complementary strands. The strands are tightly hugging one another except for one loose, floppy end of a strand, known as the toe hold. The rolling motor can be programmed by coating it with duplex DNA that is complementary to a DNA target — a sequence of interest. When the molecular motor encounters the DNA target as it rolls along its RNA track, the DNA target binds to the toe hold of the duplex DNA, strips it apart, and anchors the motor into place. The computer read out becomes simply “motion” or “no motion.” 

“When I first saw this concept work during an experiment, I made this really loud, excited sound,” Piranej recalls. “One of my colleagues came over and asked, ‘Are you okay?’ Nothing compares to seeing your idea come to life like that. That’s a great moment.” 

These two basic logic gates of “motion” or “no motion” can be strung together to build more complicated operations, mimicking how regular computer programs build on the logic gates of “zero” or “one.” 

Piranej took the project even further by finding a way to pack many different computer operations together and still easily read the output. She simply varied the size and materials of the microscopic spheres that form the chassis for the DNA-based rolling motors. For instance, the spheres can range from three to five microns in diameter and be made of either silica or polystyrene. Each alteration provides slightly different optical properties that can be distinguished through a cell phone microscope.

The Salaita lab is working to establish a collaboration with scientists at the Atlanta Center for Microsystems Engineered Point-of-Care Technologies, an NIH-funded center established by Emory and Georgia Tech. They are exploring the potential for the use of the DNA-computing technology for home diagnostics of COVID-19 and other disease biomarkers. 

“Developing devices for biomedical applications is especially rewarding because it’s a chance to make a big impact in people’s lives,” Piranej says. “The challenges of this project have made it more fun for me,” she adds. 

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Monarch butterflies increasingly plagued by parasites, study shows

"Our findings suggest that tens of millions of eastern monarch butterflies are getting sick and dying each year from these parasites," says Emory evolutionary biologist Jaap de Roode, senior author of the study.

By Carol Clark

Monarch butterflies, one of the most iconic insects of North America, are increasingly plagued by a debilitating parasite, a major new analysis shows. The Journal of Animal Ecology published the findings, led by scientists at Emory University. 

The analysis drew from 50 years of data on the infection rate of wild monarch butterflies by the protozoan Ophryocystis elektrosirrha, or O.E. The results showed that the O.E. infection rate increased from less than one percent of the eastern monarch population in 1968 to as much as 10 percent today. 

“We’re seeing a significant change in a wildlife population with a parasitism rate steadily rising from almost non-existent to as high as 10 percent,” says Ania Majewska, first author of the paper and a post-doctoral fellow in Emory’s Department of Biology. “It’s a signal that something is not right in the environment and that we need to pay attention.” 

 

The O.E. parasite invades the gut of the monarch caterpillars. If the adult butterfly leaves the pupal stage with a severe parasitic infection, it begins oozing fluids from its body and dies. Even if the butterflies survive, as in case of a lighter infection, they do not fly well or live as long as uninfected ones. 

The rise in parasitism, the researchers warn, may endanger the mass migration of the monarchs, one of the most spectacular displays in the animal kingdom, involving hundreds of millions of butterflies. Each fall, the western monarch population flies hundreds of miles down the Pacific Coast to spend the winter in California. Meanwhile, on the other side of the Rocky Mountains, eastern monarchs fly from as far north as the U.S.-Canadian border to overwinter in Central Mexico, covering as much as 3,000 miles. 

“Our findings suggest that tens of millions of eastern monarch butterflies are getting sick and dying each year from these parasites,” says Jaap de Roode, Emory professor of biology and senior author of the study. “If the infection rates keep going up, fewer and fewer monarchs will be able to survive to migrate to their overwintering sites.” 

One contributor to the rise in the parasitism rate is the increased density of monarchs in places where they lay their eggs, the study finds. The researchers posit that the increased density may be due to many factors, including the loss of wildlife habitat; the widespread planting of exotic, non-native species of milkweed; and by people raising monarchs in large numbers in confined spaces.

Co-authors of the paper are Sonia Altizer and Andrew Davis of the University of Georgia Odum School of Ecology. 

"Monarchs are incredible animals," says Ania Majewska, first author of the study, shown in the Monarch Butterfly Biosphere Reserve in Mexico.

Majewska began studying monarchs eight years ago while a graduate student at the University of Georgia. She joined the De Roode lab at Emory in 2019, funded by the NIH program Fellowships in Research and Science Teaching. 

“Monarchs are incredible animals,” she says. “Each one is only as heavy as a paperclip but they can fly so far and they are incredibly resilient.” 

The Monarch Butterfly Biosphere Reserve in Mexico, where the eastern monarchs overwinter in pine and fir forests, is a World Heritage Site and an important generator of tourism income. “The trees can become so heavy with monarchs that sometimes branches break off and fall,” Majewska says. “When sunlight hits the clusters the monarchs explode like confetti. It’s a magical sight.” 

The butterflies arrive in large numbers in Mexico near the Day of the Dead, when families gather around the gravesites of their loved ones. For traditional cultures in the region, monarchs have come to represent the souls of ancestors returning to visit for the celebrations. 

In addition to the monarch migration’s natural beauty, economic and cultural significance, it plays an ecological role, as the butterflies pollinate plants and provide food for wasps, ants and other invertebrate predators. 

Birds, however, tend to avoid the monarchs, as the butterfly’s striking coloration of orange, black and white is a warning sign that it may be poisonous to them. 

Monarchs overwintering on a tree in Mexico. (Photo by Jaap de Roode)

When monarchs leave their overwintering sites in the spring, they fly north and lay their eggs. Their caterpillars feed on any of dozens of species of milkweed plants, including some species that contain high levels of cardenolides. These chemicals do not harm the caterpillars, but make them toxic to some predators even after they emerge as adults from their chrysalises. 

In 2010, Jaap de Roode discovered that monarchs also use cardenolides as a kind of drug. Experiments in his lab showed that a female infected with the O.E. parasite prefers to lay her eggs on a toxic species of milkweed, rather than a non-toxic species. Uninfected female monarchs, however, showed no preference. While cardenolides do not cure the caterpillars of parasites, they can lessen the severity of an infection. 

For the current paper, the researchers wanted to investigate the O.E. infection rate in monarch populations over time. They accessed multiple available data sets, which were mostly for the eastern monarchs. The data included samples going back to 1968 collected by the late Lincoln Brower, an entomologist who specialized in monarchs, and by other researchers through the decades. 

The results showed the rise in the parasitism rate remained low in the eastern monarch population for several decades before shooting up beginning in the 2000s, then making a slight dip in recent years.

Monarchs caterpillars feed exclusively on milkweed plants. (Photo by Jaap de Roode)

Among the factors that may be contributing to the increased monarch density associated with the rise in parasitism, the researchers note, is the loss of natural habitat and agricultural practices that have reduced the places where milkweed is found. Milkweed used to proliferate amid crops in the Midwest, for instance, but farmers increasingly use genetically engineered herbicide-resistant crops. That allows them to spray their fields to eradicate weeds. 

Since milkweed is the sole source of food for monarch caterpillars, and fewer of the plants are available, the female monarchs must cluster more densely to lay their eggs and the butterfly “nurseries” become more crowded with caterpillars. 

“One thing that the COVID-19 pandemic taught us is that social distancing can help reduce the spread of an infectious disease,” de Roode says. “The same holds true for monarchs and the O.E. parasite.” 

Around the year 2000, the researchers note, conservation groups began planting exotic species of milkweed to try to support the monarch population, which has been declining. Ironically, this conservation effort may have fueled more parasitism. “The exotic species of milkweed tend to have more cardenolides than native species,” Majewska explains, “so infected female monarchs may be seeking the exotic species out, adding to the density problem.” 

The researchers further hypothesize that people raising monarch caterpillars in large numbers — to support conservation efforts or for commercial purposes — may be keeping them in crowded conditions that foster the spread of the parasite. 

“Ultimately, a continuing rise in the monarch’s parasitic infection rate could cause the species to suffer significantly,” Majewska says. “If tens of millions of them are dying annually from parasitic infections, then an extreme weather event during the winter in Mexico might reduce the population to a level that could be dangerous for their genetic diversity.” 

“Parasitism is often overlooked in conservation efforts,” de Roode adds, “but our findings show how parasites can have a massive impact on wildlife.” 

The research was supported by the National Institutes of Health and the National Science Foundation.

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Heartland virus identified in lone star ticks in Georgia

The lone star tick, named for the distinctive white spot on its back, is the most common tick in Georgia.  Emory researchers detected Heartland virus in three different specimen samples of lone star ticks collected in central Georgia. (CDC/James Gathany)

By Carol Clark

Heartland virus is circulating in lone star ticks in Georgia, scientists at Emory University have found, confirming active transmission of the virus within the state. The journal Emerging Infectious Diseases published the findings, which include a genetic analysis of the virus samples, isolated from ticks collected in central Georgia. 

The research adds new evidence for how the tick-borne Heartland virus, first identified in Missouri in 2009, may evolve and spread geographically and from one organism to another. 

“Heartland is an emerging infectious disease that is not well understood,” says Gonzalo Vazquez-Prokopec, associate professor in Emory’s Department of Environmental Sciences and senior author of the study. “We’re trying to get ahead of this virus by learning everything that we can about it before it potentially becomes a bigger problem.” 

Vazquez-Prokopec is a leading expert in vector-borne diseases — infections transmitted from one organism to another by the bite of a vector, such as a tick or mosquito. 

Yamila Romer, a former post-doctoral fellow in the Vazquez-Prokopec lab, is first author of the new paper. Co-author Anne Piantadosi, assistant professor in Emory School of Medicine’s Department of Pathology and Laboratory Medicine, conducted the genetic analyses. 

"Ticks are both fascinating and terrifying," says study co-author Steph Bellman, shown in the field with a vial of ticks. "They represent a large threat to human health that a lot of people may not realize." Bellman is an MD/Phd student in Emory's School of Medicine and Rollins School of Public Health.

The study detected Heartland virus in three different specimen samples of lone star ticks — collected in different locations and at different times — and including both the nymph and adult stages of the ticks.

The genetic analysis of the three viral samples showed that their genomes are similar to one another, but much different from the genomes of Heartland virus samples from outside the state. “These results suggest that the virus may be evolving very rapidly in different geographic locations, or that it may be circulating primarily in isolated areas and not dispersing quickly between those areas,” Vazquez-Prokopec says. 

The Heartland virus was discovered in 2009 in northwest Missouri after two local men were hospitalized with high fevers, diarrhea, muscle pains, low counts of white blood cells and platelets, and other symptoms similar to known tick-borne diseases. Researchers soon realized the men were infected with a novel virus, which was christened Heartland, and later traced to lone star ticks. Further studies found antibodies to the virus in blood samples from deer and some other wild mammals. 

The Centers for Disease Control and Prevention currently recognizes 18 tick-borne diseases in the United States, many of them newly emerging. One of the most well-known tick-borne illnesses is Lyme disease, caused by a bacterium, which in recent decades has grown into the most common vector-borne disease in the country. The black-legged tick, also known as the deer tick, is the vector for transmission of the bacteria that causes Lyme disease and the white-footed mouse is the primary reservoir for the bacterium. The tick larvae can become infected when they feed on the blood of the mice and other small mammals and birds that may be harboring the bacterium. The infected larvae grow into nymphs and adult ticks that can then move into other hosts, including deer and humans. 

While the complex transmission cycle for Lyme disease is well characterized, many questions remain about how the Heartland virus moves among different species. 

The researchers used flags of white flannel to collect the tick specimens.

Since it was first discovered in 2009, more than 50 cases of Heartland virus have been identified in people from 11 states in the Midwest and Southeast, according to the Centers for Disease Control and Prevention. Many of the identified cases were severe enough to require hospitalization and a few individuals with co-morbidities have died. The actual disease burden is believed to be higher, however, since Heartland virus is still not well known and tests are rarely ordered for it. 

A retroactive analysis uncovered a single confirmed human infection of Heartland virus in Georgia, in a Baldwin County resident who died with what was then an unidentified illness in 2005. The human case prompted analysis of serum samples collected in past years from white-tailed deer in central Georgia. The results showed that deer from that area have been exposed to the Heartland virus since at least 2001. 

To better assess the risk for human disease in the area, Vazquez-Prokopec wanted to learn whether lone star ticks are currently carrying Heartland virus in central Georgia. 

Members of the field research team collected ticks from the rural landscape near the Piedmont National Wildlife Refuge. Even during the hot Georgia summers, team members wore long shirts and long pants tucked into long socks, with the top of the socks sealed with duct tape. They further protected themselves with bug spray and by conducting visual checks for ticks on themselves before and after leaving the field. 

The lone star tick, named for a distinctive white spot on its back, is the most common tick in Georgia and is widely distributed in wooded areas across the Southeast, Eastern and Midwest United States. They are tiny, about the size of a sesame seed in the nymph stage, and barely a quarter-of-an-inch in diameter as adults. 

“Lone star ticks are so small that you may not feel them on you or even notice if you’ve been bitten by one,” says Steph Bellman, a co-author of the study. Bellman is an MD/PhD student in Emory’s School of Medicine and Rollins School of Public Health, focused on environmental health. 

A vial of ticks collected in the field.

The team used “flagging” as a collection technique. A flag of white flannel on a pole is swished in a figure-eight motion through the underbrush. “Every so often, you lay the flag down and use a pair of tweezers to remove any ticks that you find on it and put them into a vial,” Bellman explains. 

Through this painstaking method, the team collected nearly 10,000 specimens from sites in Georgia’s Putnam County and Jones County, both adjacent to Baldwin County. Specimens were separated into groups, each containing either five adults or 25 nymphs, then crushed and put into a solution to test for the presence of the Heartland virus. 

The results suggested that about one out of every 2,000 of the collected specimens carried the Heartland virus. One adult and one nymph sample collected on the same date tested positive from a site in Putnam County, a private property used for hunting. A second sample of adult ticks, collected on a different date from a stretch of woods along a highway in Jones County, also tested positive. 

The researchers are now expanding the scope of the work. They will collect ticks across Georgia for testing and conduct spatial analyses with the aim of understanding factors that may raise the risk for Heartland virus. 

“We want to start filling in the huge gaps in knowledge of the transmission cycle for Heartland virus,” Vazquez-Prokopec says. “We need to better understand the key actors that transmit the virus and any environmental factors that may help it to persist within different habitats.” 

Climate change is fueling warmer and shorter winters, increasing opportunities for some species of ticks to breed more frequently and to expand their ranges. Land-use changes are also strongly associated with tick-borne diseases, as more human habitats encroach on wooded areas and the loss of natural habitat forces wildlife to live in denser populations. 

“Ticks are both fascinating and terrifying,” Bellman says. “We don’t have effective ways to control them and they are a vector for many nasty diseases. They represent a large threat to human health that a lot of people may not realize.” 

The Asian longhorned tick is an invasive species that has been found in Georgia and 16 other states. (CDC/James Gathany)

The Prokopec Lab is also investigating the arrival of the Asian longhorned tick (Haemaphysalis longicornis) in Georgia, funded by a seed grant from the U.S. Department of Agriculture. 

Long established in China, Japan, Russia and parts of the Pacific, the Asian longhorned tick was first detected in the United States in 2018, in New Jersey. The tick has since spread to 17 states, including Georgia, where it was found on a farm in Pickens County in 2021. 

The Asian longhorned tick reproduces asexually and a single female can generate as many as 100,000 eggs, rapidly producing massive amounts of offspring that feed on livestock. So many ticks can be covering a single sheep or cow that the loss of blood physically weakens or, in extreme cases, kills the animal. 

The Asian longhorned tick also carries bacterial and viral pathogens that can infect humans, including severe fever with thrombocytopenia syndrome virus (SFTSV), also known as Dabie bandavirus. Human cases of SFTS, a hemorrhagic fever, emerged in China in 2011 and have since been identified in other parts of Asia. 

“We are investigating not only the potential agricultural impact of the Asian longhorned tick in Georgia, but the potential for this invasive tick to spread SFTS and other diseases to people,” Vazquez-Prokopec says. 

Of particular concern is the fact that the Heartland virus shares genomic similarities with SFTSV, he adds. 

“We will be gathering data to help support tick surveillance efforts by public health officials in Georgia,” Vazquez-Prokopec says. “Tick-borne diseases are a real and growing threat and the best way to deal with them is not to panic, but to do the science needed to learn everything we can about them.”  

Additional co-authors of the current paper include Uriel Kitron, professor in Emory’s Department of Environmental Sciences; Oscar Kirstein, an Emory post-doctoral fellow in the Prokopec Lab; Daniel Mead and Kalya Adcock, from the University of Georgia; and Zhuorn Wei, a former Emory research assistant. 

Funding for the work was provided by a grant from the Emory University Research Council.

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Atlanta Science Fest celebrates the wonders all around us

A celebration of science once again takes metro Atlanta by storm with the return of the Atlanta Science Festival, ongoing through March 26. More than 100 activities, planned throughout the city, invite families to experience the thrills of discovery, from nature walks to expert talks and hands-on STEM learning opportunities. 

“The festival offers ways for people of all ages to learn something new and to spark a new interest,” says Meisa Salaita, the executive co-director of Science ATL, the non-profit organization that produces the Atlanta Science Festival. “You may not realize that your child has a secret knack for chemistry, or that you enjoy birdwatching, until getting immersed in it.” 

The Atlanta Science Festival, now in its ninth year, was co-founded by Emory, Georgia Tech and the Metro Atlanta Chamber.

Read more about events featuring the Emory community.

Data-driven study digs into the state of U.S. farm livelihoods

"Farmers are fundamental to our survival, their work is risky and difficult, and ensuring their quality of life is necessary for U.S. agriculture to persist," says Emily Burchfield, Emory assistant professor of environmental sciences and lead author of the study.

By Carol Clark

U.S. agricultural systems are world leaders in the production of food, fuel and fiber. This high level of production enables U.S. consumers to spend an average of only 8.6 percent of their disposable income on food, a percentage that has been trending downward since 1960. Growing evidence, however, shows that many hidden costs of cheap food may be passed on through factors such as reduced nutritional content, environmental degradation and the diminishing livelihoods of U.S. farm operators. 

A major new study led by Emory University digs deeper into the question of why, despite the extraordinary productivity of U.S. agriculture, U.S. farm operators are systematically losing money. The journal Frontiers of Sustainable Food Systems published the analysis, which drew from publicly available data from the U.S. Department of Agriculture, the U.S. Bureau of Economic Analysis and other sources. 

“It’s not that agriculture as a sector is not profitable,” says Emily Burchfield, assistant professor in Emory’s Department of Environmental Sciences and lead author of the study. “It’s that, despite hard work and significant financial risk, many of the people who operate U.S. farms are not able to make a decent living at it.” 

Rising input costs, shrinking production values, commodity specialization and challenges to land access all appear to be connected to declining farm operator livelihoods, the study concludes. 

“We’ve shown in a quantitative, systematic way the extent to which these trends are happening and, in many cases, how they appear to be worsening,” Burchfield says. 

An online data repository

“People who work in the agricultural space already know that it is difficult to make a living as a farmer,” she adds. “In this paper, we’ve cleaned and merged tremendous amounts of data from multiple sources to bring key information together into one place. This allows us to tell a more complete and clear story about how and why this is happening at a national scale.” 

The researchers deposited the cleaned and merged data into a free, online repository (https://github.com/blschum/US-Farming-Data-Narrative) so that other agricultural stakeholders can easily access it. They hope that their “one-stop,” centralized data hub on farmer livelihoods will serve as an educational tool and inspire more research into the topic. 

The USDA reported in 2020 that the average funds generated by farm operators to meet living expenses and debt obligations, after accounting for production expenses, have been negative for nine out of the last 10 years. In 2017, for instance, median net-cash farm income was $1,035 in the red per farm household in the country. 

Paying to farm

In many regions of the United States, the authors write, farm operators actually have to pay to engage in the labor- and time-intensive act of operating a farm. 

“What we were really surprised to find in the data is that the low, or negative, median farm operator income applies even when you factor in government subsidies,” Burchfield says. “Given that the federal government is subsidizing farming with billions of dollars annually, it raises the question of how we might do so more effectively. How are we going to convince folks to continue growing our food if they are locked into a system where they can’t make money?” 

Burchfield’s research combines spatial-temporal, social and environmental data to understand the future of food security in the United States, including the consequences of a changing climate. 

Co-authors of the current paper include: Britta Schumacher, a former Emory research assistant in Burchfield’s lab; Andrea Rissing, an Emory post-doctoral fellow in the lab; and Kaitlyn Spangler, a post-doctoral fellow at Penn State. 

Relying on off-farm income

Understanding how much income individual farms are losing on average is complicated by farm households often having a family member bringing in income through a non-farm occupation, Burchfield notes. In 2019, the USDA reported that on-farm production contributes to less than 25 percent of farm household income, on average, with the remaining 75 percent earned off-farm. This suggests that many farmers rely on off-farm income to stay afloat. 

“Farming is one of the hardest jobs on the planet,” Burchfield says, “and it’s going to get even harder due to climate change. The combination of more gradual shifts in average climate conditions, and the increased prevalence of extreme weather events, presents a serious challenge to farmers.” 

These ongoing challenges, the authors argue, require an urgent rethinking of how federal subsidies can play a role in encouraging and supporting new, adaptive approaches to agriculture. 

U.S. farm operations currently cover approximately 900 million cultivated acres, more than half of the nation’s land area. And three crops — corn, soy and wheat — are cultivated exclusively on more than two thirds of agricultural acres. 

“A lack of crop diversification can make farming increasingly brittle and less adaptable,” Burchfield says. “Climate change, meanwhile, makes the need for innovation and adaptation more crucial and inevitable.” 

The paper also highlights the lack of diversification among farm operators. Statistically, the “average” U.S. farmer is a 58-year-old white male. Those not identifying as white currently operate about 7 percent of farmland representing just 5 percent of operations. Only 1.4 percent of operators identify as Black, and these operators are heavily concentrated in the Southeast. And, on average, white operators receive twice as much from federal subsidy programs ($14,000 per farm) as Black operators ($6,400 per farm). 

A call for diversity of people, plants and practices

“We need better data to track the persistent inequities at the intersection of race, class and livelihoods in the agriculture space,” Burchfield says. 

She recommends finding ways to support the diversity of people, plants and practices in the national farm landscape to help address the growing issues of agricultural sustainability and climate change. “Small-scale experimentation and the emergence of grassroots alternatives along with technical innovations are all needed in order to better weather the challenges,” she says. 

Burchfield also cites the need for the availability of more fine-scale data on the livelihoods of farmers that goes beyond yields and acreage to cover issues such as access to health insurance. “Farmers are fundamental to our survival, their work is risky and difficult, and ensuring their quality of life is necessary for U.S. agriculture to persist,” she says. 

As Burchfield and her co-authors conclude: “Measuring and monitoring agricultural progress using only metrics of production, efficiency and revenue masks the lived realities of the humans operating our farms.” 

The research was supported in part by the U.S. Department of Agriculture and the National Science Foundation.

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