Insights into bee biology could ease US rules for organic honey
The spots on a leopard, the stripes on a zebra, and the mask on a raccoon are all types of coloration in mammal fur, referred to as pelage. Scientists have struggled for a long time to understand how these colorations evolved. A team of researchers recently discovered how to reconstruct the colors of ancient mammal fur using cell structures that contain the chemical pigment melanin, known as melanosomes. They hope to use this understanding of ancient mammal pelage to determine how they lived and what their environments were like.
To decipher the color of ancient mammal fur, the researchers constructed a statistical computer model to predict their fur colors based on the shape of their melanosomes. First, they needed to understand how the shapes of melanosomes control fur color in modern mammals. To measure the length and width of the modern melanosomes, the scientists used a beam of electrons like a flashlight to map them in great detail, a technique called scanning electron microscopy.
They measured the length and width of 2,615 melanosomes from the fur of 116 different living mammal species, including a Red Panda, a German Shepard, and one or more species of most types in the mammalian classification. Then they recorded the wavelengths of light reflected off each melanosome using a microspectrophotometer. These wavelengths represented the exact color of hair from each melanosome they measured. This means they now had a quantitative measurement of the color of each hair to compare with its corresponding melanosome length and width.
When they examined their data, the researchers found that spherical melanosomes produced brighter fur colors, like reds and oranges, while elongated melanosomes produced darker fur colors, like browns and grays. The researchers plotted the microspectrophotometric measurements for each melanosome as a graph showing how much light it absorbed across each possible wavelength, creating reflectance curves. Based on these data, the researchers used computer software to create a statistical model that could predict reflectance curves, and therefore color, from melanosome shape alone.
Once the researchers created a model, they needed to find fossilized mammal melanosomes to predict their fur color. Mammal fossils are rare, and pieces of cells are only preserved in the most immaculate fossil deposits. In fact, these researchers only found 6 fossils of this caliber, from Mesozoic rocks deposited around 250 million years ago, soon after mammals evolved.
The fossils came from 2 world-renowned deposits in Northeastern China, the Yanliao and Jehol biotas. They selected 5 previously studied fossils from these locations, including 1 specimen of Megaconus mammaliaformis, 1 specimen of Vilevolodon diplomylos, 2 specimens from the group Docodonta, and 1 specimen from the group Eutheria. All of these animals were small, rodent-like mammals. The researchers also discovered a new species of tree-dwelling mammal, Arboroharamiya fuscus.
The scientists used scanning electron microscopy to measure a total of 2,159 fossilized melanosomes to refine their color predictions. The fossilized melanosomes were all slightly elongated spheres and had far fewer differences in shape than in modern mammals. The researchers used their model to predict reflectance curves based on the shapes of the fossil melanosomes to determine the ancient mammals’ colors. They found that all the extinct mammals they examined likely had dark brown fur without any color patterns.
Based on these findings, the researchers suggested that most, if not all, early mammals were nocturnal, like many dark-colored mammals today. They suggested that this nocturnal lifestyle probably helped them survive the meteorite impact that wiped out the dinosaurs 100 million years later. While dinosaurs were unable to survive in the post-impact wasteland, these smaller, dark-colored mammals were more resilient and thrived in the aftermath. As mammals filled the ecological roles left by the dinosaurs, they evolved new color patterns, some based solely on camouflage, and others on new factors, like sexual selection and visual communication.
The researchers concluded that their model can predict fossilized mammal colors and help determine how these ancient animals lived. Notably, their data suggest that mammals likely stayed small and nocturnal throughout the Mesozoic until the dinosaurs were gone. Future researchers could use similar methods to uncover exactly how mammals evolved the colors we see today. For example, studying mammals closer to the impact event could reveal if it took a long time to develop diverse fur patterns, or if they began before the dinosaurs’ demise. Ultimately, similar studies could help determine whether the extinction of dinosaurs was necessary for the rise of mammals.
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Authors: María-Luisa Chas-Amil, Catedrática de Economía Aplicada, Universidade de Santiago de Compostela and Julia María Touza, Professor of Environmental Economics, University of York

As the flames advanced towards the village of Bédar, in the Almería province of Andalusia, the mayor gave a desperate order to ring the church bells to warn residents. It was not enough. The July 9 Los Gallardos fire, which claimed 13 lives and burnt 7,000 hectares, was Spain’s third deadliest on record.
Most of the victims were retired foreigners living in isolated homes, who died trapped in their vehicles or fleeing on foot along dead-end paths in a landscape dominated by scrubland and rugged terrain, most of which is difficult to access.
High temperatures and extremely dry weather turn scrub, grasslands and bushes into highly flammable fuel. This, combined with complex terrain that makes fire spread faster and unpredictably, poses an enormous challenge for firefighting efforts.
Andalusian legislation requires local emergency plans for forest fires in high-risk areas, and self-protection plans for detached buildings and housing estates. However, there is a widespread problem with compliance and implementation of these measures.
The disaster in Los Gallardos shows that this problem will only get worse, unless we take decisive and effective action that goes beyond the current dominant paradigm of simply extinguishing and resisting fire.
Where, when and how fires occur is changing. Highly destructive fires are on the rise, housing is expanding into the urban-forest interface. This exposes more homes to fire, and the the risk is increasing most quickly in scrubland and grassland areas, which are not typically associated with fire risk.
This is a major problem for communities that do not know how to respond to a risk they have not often been exposed to. We therefore need to urgently rethink how fire risk is managed.
It is unsustainable to respond only after a disaster has happened. What we need are strategies based on preparedness, mitigation and adaptation. The following eight points are particularly important in achieving this.
1. Manage social vulnerability
Wildfires exacerbate the existing social vulnerabilities that affect people’s ability to anticipate, cope with, withstand and recover from them. In high-risk areas the population may consist of elderly people, people living alone in isolated homes, with financial constraints, or who do not know the local area well.
Fires also pose a risk to local economies. Businesses – including those that provide public services and infrastructure – can be vulnerable for a range of reasons, including flammable facilities, their location, or disruptions to supply chains, essential services and staff mobility.
Targeted planning can identify and address all of these vulnerabilities.
2. Adopt nature-based solutions
Nature-based solutions have not been fully integrated into fire risk management, even though they are widely recognised as essential parts of climate change adaptation and nature restoration.
Nature-based solutions include controlled grazing, the creation of less flammable habitats, green firebreaks, and the restoration of water networks to increase ambient humidity and create areas that slow the spread of fire. These measures also bring many additional benefits for the local population and economy.
3. Create (and update) emergency, self-protection and training plans
Local authorities must draw up emergency plans that the public can access. Isolated dwellings and housing estates must have their own coordinated plans. The plans should include fire hydrants and water supply points, accessible warning systems, access and evacuation routes, and protocols for vulnerable people.
But plans alone are not enough without training. There is also a need for ongoing programmes, tailored to each community, that train people to safely maintain their homes and surroundings, familiarise them with meeting points and shelter areas, and teach them to distinguish between lockdown and evacuation.
Drills are essential. Evacuation is not the same as fleeing, and emergency response must be planned and practised.
4. Promote collective action
Risk reduction is most effective when it is community-based, as this increases overall collective resilience. This means public authorities, community organisations, and the public and private sector must all work alongside one another.
The public should also be actively involved in the design of emergency plans. This builds legitimacy, improves the capacity to respond to fires, and fosters trust and a sense of shared responsibility for preventing fires.
5. Promote integrated and coordinated governance
Fire risk management cannot be the sole responsibility of forestry or firefighting services – it needs an integrated system. All agencies that act in the area must take fire risk into account when making decisions.
In practice, this means avoiding new construction and establishing specific building regulations in high-risk areas, creating buffer zones between different land uses, and promoting uses that help to maintain fire-resilient landscapes.
6. Incentivise risk management
Economic tools and behavioural insights can be leveraged to make self-protection measures and land management the easiest and most rewarding options. This includes nudges: interventions that are designed to encourage but not force people to make certain decisions.
One example of this is payments for environmental services, which financially incentivise land management practices that reduce wildfire risk.
The role of insurance is also evolving in the face of natural and climate-related risks. Instruments are being designed based on a proactive model that incentivises individual and collective risk-reduction behaviour.
7. Improve monitoring and advance warning systems
Up-to-date information on a fire’s development is essential. Real-time monitoring systems, sensors, satellite imagery, predictive models of fire behaviour and alert applications providing detailed information can all improve response capabilities and enable safer evacuations. Integrating these tools into local management plans is a necessary investment.
8. Encourage public and private investment in long-term preparedness
Investments in prevention and preparedness provide significant returns. Growing requirements – both regulatory and voluntary – for the private sector to disclose information on nature-related risks and dependencies are generating new demand for investment products (carbon and biodiversity credits, habitat banks, environmental impact bonds, and so on).
This growing private investment must now be channelled towards measures that strengthen both people’s and the landscape’s wildfire resilience. This is to supplement, not replace public investment.
The Los Gallardos blaze serves as a reminder that we need to fundamentally change the way we understand and manage fire risk. Investment in preparedness and coordinated planning between public authorities, the private sector and the general public could be the key to ensuring that, should the alarm bells ring again, the population is ready to respond.
This article is republished from The Conversation under a Creative Commons license. Original article.
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Have you ever wondered how researchers use artificial intelligence (AI) in environmental science? Certain AI computer models can learn from scientific data and operate without manual programming, in a process called machine learning. Machine learning models can identify patterns in environmental datasets and help scientists assess public health risks linked to environmental conditions.
One well-known public health risk is the rise in antibiotic-resistant bacteria. These bacteria carry genes called antibiotic resistance genes that protect them from antibiotic medicines. As the number of these genes increases, the medicines become less effective, and diseases spread faster.
Agricultural soils are the largest reservoirs of antibiotic resistance genes, because manure from livestock like cows and pigs often contains leftover antibiotics fed to them. When used as fertilizer, this manure transfers antibiotics into the agricultural soil, where bacteria develop antibiotic resistance genes.
To better understand how antibiotic-resistant bacteria will affect global health in the future, scientists want to develop faster ways to detect antibiotic resistance genes. However, current methods of detection are slow and fail to predict future trends. To address this problem, a group of scientists from Algeria used machine learning models to predict the prevalence of antibiotic resistance genes in soil microbes under future climate scenarios, and to identify the key environmental drivers and high-risk areas.
The team compiled existing microbial data from 3 public databases: the National Center for Biotechnology Information’s Sequence Read Archive, the Metagenomic Rapid Annotations using Subsystems Technology database, and the Joint Genome Institute’s Integrated Microbial Genomes & Microbiomes database. Their final dataset contained about 2,000 agricultural soil samples from 67 countries across 6 continents. These samples represented a wide range of soil characteristics, climate conditions, and different types of antibiotic resistance genes.
They integrated the microbial dataset with climate data, including global temperature and precipitation measurements from WorldClim, and land use data, including crop types, irrigation systems, and livestock density from the European Space Agency Climate Change Initiative Land Cover maps. The researchers also included data on future climate projections for 2050 and 2070 from the World Climate Research Programme based on low, medium, and high global greenhouse gas emission scenarios.
After preparing the datasets, the team set up 6 machine learning models that differ in terms of their data size, model complexity, analytical speed, and customization. These models included Light Gradient Boosting Machine (LightGBM), eXtreme Gradient Boosting (XGBoost), Random Forest (RF), Support Vector Machine (SVM), Deep Neural Network (DNN), and Logistic Regression (LR).
They ran each model using different combinations of variables from their datasets, including soil properties, microbial community metrics, climate variables, and land use characteristics. To validate the models, the team separated the full dataset into 10 random subsets. They trained the models on 9 of the subsets, then recorded the result of the 10th subset. Each model repeated this process 10 times in a different order so that each subset was evaluated once in the results, using a technique known as stratified 10-fold cross-validation. The researchers scored each model on 5 performance metrics, including precision, sensitivity, and predictive power. Based on these results, they determined that LightGBM was the most accurate model.
They found that the LightGBM model identified soil temperature as the strongest environmental predictor of antibiotic resistance genes. At soil temperatures above 18°C (about 64°F), the number of antibiotic resistance genes increased dramatically. The model also identified soil acidity, organic carbon content, moisture, and annual precipitation as influential variables, accounting for 71% of the increase in antibiotic resistance genes under future climate scenarios. Likewise, the LightGBM model predicted that the number of high-risk areas would increase by 35% under the high-emissions scenario, with South Asia, Sub-Saharan Africa, and Mediterranean Europe as the most vulnerable regions.
Based on the LightGBM model output, the team concluded that soil conditions will change to favor antibiotic resistance genes under all future climate scenarios. They also suggested that LightGBM is a fast and effective model for environmental predictions that could be used to assess other climate change risks such as natural disasters. They recommended that future researchers explore how to apply machine learning methods to early warning systems and utilize machine learning results in environmental management decisions.
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If you’ve ever swum in the ocean and been touched by seaweed, there’s a good chance it was Sargassum! This free-floating seaweed can have population explosions in coastal waters, degrading water quality, ecosystems, fisheries, and tourism. However, despite its drawbacks, scientists think that Sargassum could be useful for extracting valuable metals, known as rare earth elements (REEs).
REEs are classified by their average masses and atomic weights. Light REEs include cerium, praseodymium, and neodymium, middle REEs include gadolinium, terbium, and dysprosium, and heavy REEs include erbium, thulium, and ytterbium. These metals are used in magnets, electronic motors, wind turbines, spacecraft, and more. Our current methods of extracting REEs, open-pit mining and chemical processing, are invasive, causing habitat loss and producing toxic waste. Additionally, REEs are difficult to import due to restricted access worldwide. But what if these metals could be extracted using natural methods?
Scientists from Woods Hole and UCLA recently tested whether Sargassum could accumulate REEs, creating a sustainable solution to these problems. They harvested Sargassum at Waterfront Park in Woods Hole, rinsed the wet samples, and stored them in sterilized, filtered seawater, which they aerated with 12-hour cycles of light and dark to keep the Sargassum alive. They dried another set of samples in the sun under controlled outdoor conditions, stored them in sealed containers, and later rehydrated them in seawater for 3 hours before the experiments.
For each experiment, they added 5 grams (about 0.2 ounces) of Sargassum to solutions containing a mixture of 9 REEs – cerium, praseodymium, neodymium, gadolinium, terbium, dysprosium, erbium, thulium, and ytterbium – in concentrations totalling 0.1 micromolar (μM) REEs, 11μM REEs, 100 to 110μM REEs, and 575 to 600μM REEs. They performed each experiment 4 times: twice with fresh seaweed and twice with rehydrated seaweed.
The researchers removed 1 gram (about 0.04 ounces) of seaweed from each solution after 1, 3, and 7 days, and dissolved it in acid to release the REEs it had absorbed. They analyzed the concentrations of REEs in each seaweed sample and the leftover solutions using 2 different plasma-based methods. They used these REE concentrations to calculate the ratio of REEs in the Sargassum versus in the solution, known as the bioconcentration factor, to determine how effectively the seaweed absorbed REEs.
They found that after 7 days at lower REE concentrations (0.1μM), the fresh seaweed had bioconcentration factors of over 1,000. At higher REE concentrations (11μM), their bioconcentration factors ranged from about 400 to 700. However, these levels of REEs were eventually toxic to the fresh Sargassum, so they died after 2 weeks. In addition, the higher REE concentrations of 100 to 600μM were immediately toxic to the fresh Sargassum, which died within 1 day in solution.
The researchers determined that once the seaweed died, it could no longer actively take up REEs into its tissues but could only accumulate them on its surface or adsorb them. Adsorption can be thought of as a powdered donut – when the surface is covered with powdered sugar, no more powder fits on the donut. Similarly, there was a limit to how many REEs could stick to the Sargassum. Due to this limit, the fresh seaweed samples had bioconcentration factors below 250 in the highest REE concentrations. In contrast, the rehydrated Sargassum consumed less REEs at lower concentrations, but didn’t experience toxicity and continued to accumulate REEs at higher concentrations.
Finally, the team compared Sargassum to a common industrial method of accumulating REEs, known as activated carbon. REEs bond easily to activated carbon because of its abundant surface area and high porosity. Both materials accumulated a similar amount of REEs in solutions of 0.1μM REEs. However, at 575 to 600μM REEs, Sargassum accumulated about twice as many REEs as activated carbon, especially the heavier REEs.
The researchers concluded that Sargassum is a natural hyper-accumulator, meaning it successfully concentrates REEs. However, they recommended that future researchers test whether Sargassum performs the same in the natural environment as it does in the lab. If so, Sargassum could be used to accumulate REEs from wastewater, like mine drainage, or other water sources with higher concentrations of REEs. Regardless, they suggested that using Sargassum to obtain REEs could simultaneously expand global access to these metals and mitigate toxic blooms.
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Nitrogen is an essential building block of proteins, amino acids, and DNA. Without nitrogen, cells can’t function or reproduce. Nitrogen is abundant in the atmosphere as dinitrogen gas, but plants and animals can’t access atmospheric nitrogen. Instead, we rely on biologically available forms like ammonia and nitrate.
Specialized microbes can transform atmospheric nitrogen into ammonia via a process called biological nitrogen fixation. Nitrogen-fixing soil bacteria have a unique protein complex, the nitrogenase complex, that facilitates this nitrogen transformation. The nitrogenase complex is activated by a group of genes known as nif genes.
Legume plants like peanuts, peas, and beans have nitrogen-fixing bacteria in the soil zone around their roots, called the rhizosphere. The symbiotic relationship between nitrogen-fixing soil bacteria and legume plants supplies most of the biologically available nitrogen to life on Earth.
Bacteria attached to plant roots “feed” nitrogen to plants through the soil, and in turn receive organic acids for energy from plants performing photosynthesis. Source: Wikimedia Commons
However, one piece of the puzzle remains unexplored: the role of soil viruses in these nitrogen transformations, referred to as the nitrogen cycle. Viruses are microscopic particles made up of genetic material and proteins, but they can’t reproduce without a host cell. Scientists consider viruses to be biological entities that are halfway between living and non-living.
To reproduce, viruses contact a host cell and inject their genetic material into it. The virus’s genetic material takes over the host cell’s genome and forces the cell to produce proteins that assemble into new viruses. As new viruses are created, they can incorporate genes from the host cell into their own genetic material. Genes that are transferred from a host cell to a virus are known as auxiliary metabolic genes (AMGs). Viruses can carry AMGs and pass them to other hosts or use them to increase their own ecological fitness.
Scientists from China, Spain, and the Czech Republic set out to investigate whether viruses from legume roots could increase local soil nitrogen fixation by expressing nif AMGs or by transferring nif genes to other bacteria. First, they determined the global distribution of viral nitrogen-fixing genes by analyzing about 8.6 million viral genomes from the Integrated Microbial Genomes/Virus database. They looked for the DNA sequences of known nitrogen-fixing genes and the locations where the viruses were sampled. They found that only 0.003% of the viruses in the database had at least 1 nitrogen-fixing gene, but they clustered in the same locations as nitrogen-fixing bacteria.
The team also found 3 types of viruses that most commonly carried nitrogen-fixing genes: Kyanoviridae, Nudiviridae, and Bronfenbrennervirinae. Kyanoviridae viruses carried a nif gene called nifU. The researchers used a computer program called DRAM-v to confirm that nifU was a fully functional gene and a real tool that viruses could use.
Next, the team collected soil samples from a cowpea field in Nanjing, China, to test whether the cowpea roots influenced the abundance of viruses using nitrogen-fixing genes. They collected soil from the cowpea rhizospheres and soil away from the plants. They analyzed both viral and bacterial RNA in the soil samples to identify active genes, using a sequencing process called metatranscriptomics. They found that the viral nifU gene was actively expressed in the cowpea rhizosphere samples more than in the non-crop soil. Although about 96% of nifU genes were being expressed by bacteria, viruses contributed about 4%.
The researchers then assessed whether rhizospheric viruses changed the amount of nitrogen being fixed in these soils. They set up small, enclosed containers of sterile soil and added either bacteria or a mixture of bacteria and viruses extracted from the cowpea rhizospheres. They found that soil with viruses had higher total nitrogen (36 milligrams per kilogram, or mg/kg) than soil without viruses (17 mg/kg).
Finally, they adjusted the air in each container to have a different form of dinitrogen gas. Atoms of the same element that have different atomic masses are known as isotopes. Nitrogen has 2 stable isotopes: lighter nitrogen-14 and heavier nitrogen-15. Bacteria or viruses that fix nitrogen at natural isotope abundances will take up nitrogen-14. But scientists can track who in the population fixes nitrogen by adding nitrogen-15 to the air, a process called nitrogen-15 stable isotope probing. Nitrogen-fixers will incorporate the heavy nitrogen-15 into their biomass over time and increase their weight, allowing researchers to separate and identify them.
The team grew the bacteria and viruses with nitrogen-15 for 35 days, then used stable isotope probing to separate the nitrogen fixers. They detected viral nifU AMGs among the heavier biomass, confirming that rhizospheric viruses were fixing nitrogen.
The team concluded that rhizospheric viruses and the viral nifU AMG can increase nitrogen fixation in cowpea soils. The team suggested that although viruses with nitrogen-fixing genes are rare, they can influence the soil nitrogen cycle. They recommended that future researchers further test the contribution of viral nifU genes to plant nitrogen fixation with controlled infection experiments.
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In March 2021, the carcasses of at least 260 marine organisms from 81 species, including large animals called megafauna, washed ashore in South Africa. Scientists questioned whether this event was the result of an extreme temperature drop that can happen when deep, cold water rises to the surface along coastlines. Scientists refer to these rapid cooling events as coastal upwelling.
Climate change is making oceans warmer, but it’s also making coastal upwelling stronger, with unknown consequences for marine megafauna. Scientists recently studied 2 boundary currents that are rapidly warming and creating strong upwelling near the edges of sharks’ geographic ranges: the Agulhas Current in southern Africa and the East Australian Current in eastern Australia. They wanted to determine whether climate-driven changes in upwelling zones are making cold-shock events more frequent and intense, and how these events are pushing sharks beyond their temperature limits.
First, the researchers analyzed sea surface temperature data from satellites to see if rapid cooling from upwelling caused the mass marine die-off in 2021. They also obtained hourly temperature recordings from temperature loggers to measure subsurface temperature changes during the event. They found that during the March 2021 event, sea surface temperatures along the coast dropped by up to 7°C (12°F) in less than 48 hours, from 24°C (75°F) to below 17°C (63°F). Subsurface temperatures dropped faster, by more than 9°C (16°F) in 24 hours, from 21°C (70°F) to 12°C (54°F).
Bullsharks experience physiological stress at temperatures below 19°C (66°F), which is near their lower thermal limit, when migrating through rapid cooling zones. Therefore, the researchers deduced that during the 2021 cold-shock event, the sharks were exposed to temperatures several degrees below their thermal limit, possibly more than 5°C (or 10°F) colder.
The researchers also tagged 66 bull sharks with acoustic and satellite transmitters – including 41 at the Agulhas Current in South Africa and 25 at the East Australian Current in eastern Australia – to determine how they responded near their lower thermal limits in these zones. The acoustic tags record when sharks pass underwater receivers, providing information on their movements, locations, and water depths at those specific locations. In contrast, satellite tags continuously record the water temperatures and depths the sharks experience over time.
The researchers used these data to compare sharks living in warm subtropical waters with those living in cooler waters at the edge of their temperature range. The researchers found that low temperatures that persisted for long periods prevented the sharks and other megafauna from physiologically recovering. They saw that some sharks try to swim to shallower depths and look for warmer water, but cooling sometimes happened faster than they could respond.
The researchers also obtained wind records from the South African Weather Service to determine if upwelling-favorable winds happened before the 2021 event. They reported strong easterly winds pushing cold water on the surface along the coastline immediately before the event occurred. Because the cooling, strong winds, and animal deaths happened at the same time and place, the researchers inferred that upwelling was the main reason for the die-off.
Finally, the researchers examined 41 years of sea surface temperature data and used mathematical models to compute changes in the frequency and intensity of these events. Their analysis showed that rapid cooling events linked to upwelling can last a lot longer than the usual 1 to 3 days. For example, the March 2021 event lasted for 7 days.
They found that these events have increased in both frequency and intensity in the past decades, and produce more extreme temperature drops than typically happen within 24 hours. Their results suggested that the 2021 die-off was part of an increasing trend, where warming oceans allow species to move into different areas, but intense upwelling can suddenly expose them to fatal cold events. This pattern is what scientists call a climate bait-and-switch.
The researchers concluded that climate change is making coastal upwelling stronger, which can push marine megafauna beyond their thermal limits, even when initial warming appears to be beneficial. Their findings highlight an understudied aspect of climate change in the context of how temperature and upwelling cause shifts in species survival. They concluded their findings could help predict how marine ecosystems respond to future changing ocean conditions.
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For millennia, farming in Switzerland did not reduce plant diversity but helped increase it, researchers have shown in a detailed reconstruction covering the past 7000 years. Only recent decades paint a different picture.

The fall of the Roman Empire and major plague outbreaks: These events not only affected people but also reduced plant diversity on the Swiss Plateau, as human land use temporarily declined. Researchers led by Dr. Fabian Rey and Professor Oliver Heiri at the University of Basel report 1.
Their analyses are based on sediment deposits in three Swiss lakes: Moossee near Bern, Burgäschisee near Herzogenbuchsee, and Hüttwilersee in Thurgau. The researchers extracted sediment cores from these lakes and then analyzed the material deposited in the sediments over the course of millennia. This allowed them to infer and date variations in both plant diversity and agricultural land use in the areas surrounding the lakes.
“This is an exceptionally comprehensive and precisely dated dataset,” says Oliver Heiri. “It allows us to reconstruct changes in plant diversity around the lakes over the past 7000 years at a time resolution comparable to long-term ecosystem studies in modern ecology – and for a period long before modern ecology existed.”
Since the Neolithic period, plant diversity increased with increasing agricultural activity. “You might think that human impact must be bad for plant diversity, because that’s what we see today,” says Fabian Rey. “But agriculture back then made the landscape more diverse.” Before early agricultural activities, the Swiss Plateau was largely covered by forest and was therefore a relatively uniform ecosystem.
“As agriculture expanded, a mosaic of habitats emerged over time,” says Rey. Fields, pastures, hedgerows, and later orchards of tall fruit trees alternated across relatively small areas. This provided varied conditions for plants adapted to those specific environments.
However, there were also recurring periods when plant diversity declined sharply: For example, during the Migration Period following the fall of the Roman Empire, or when plague outbreaks claimed many lives in the Middle Ages. “In times when people were less able to continue farming, the forest grew back and plant diversity declined at the landscape level,” explains Heiri.
More agriculture, more biodiversity: However, this parallel trend lasted only until around World War II. Over the past 80 years, plant diversity has declined sharply. The research team attributes this to the intensification of agriculture since then.
Instead of a fragmented mosaic of habitats, large, uniform areas have emerged that are easier to farm using heavy machinery. The increasing use of fertilizers and pesticides also caused many specialized plant species to retreat.
“However, our data also show that plant diversity has recovered from earlier declines when people returned to farming practices that included varied landscapes,” says Rey. This suggests that the trend of the past 80 years could also be reversed if farming practices change again.
The data for the study are based on more than a decade of analyses of sediment cores, conducted in close collaboration with researchers from the University of Bern and the Department of Archaeology of Canton Thurgau. To collect the data, Fabian Rey extracted pollen samples from every centimeter of the cores, which he chemically processed, prepared, and analyzed under a microscope. For each sample, he identified 500 pollen grains, enabling him to determine the diversity of plants around the lake.
The intensity of agricultural use during each period was determined based on the presence of specific pollen in the samples – including both cultivated plants and species that thrive on farmland – as well as a comparison with archaeological and historical data.
The scientists dated the layers using the 14C method, a technique for determining the age of organic material. The sediment cores date back approximately 7000 years, to the Neolithic period.
 
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In the dense and biodiverse expanse of the Brazilian Amazon, the interplay between human activity and ecological systems has long shaped the epidemiology of vector-borne diseases. Recent research delves into how the agrarian economy and socioenvironmental contexts are critical determinants of disease co-occurrence patterns in this pivotal region. This investigation illuminates the complex network of factors influencing vector-borne illnesses, shedding light on how environmental modifications and economic activities intertwine to affect human health.
Vector-borne diseases, illnesses transmitted by organisms such as mosquitoes, ticks, and other arthropods, represent a significant burden in tropical regions worldwide. The Amazon Basin, renowned for its vast tropical rainforest and intricate ecosystems, harbors multiple pathogens that cause diseases like malaria, dengue, Chagas disease, and leishmaniasis. However, it has been increasingly evident that these diseases do not occur in isolation but rather exhibit notable patterns of co-occurrence that hinge on intertwined environmental and socioeconomic factors.
The study conducted by Barbosa, Lana, Dal’Asta, and colleagues offers a groundbreaking analysis by mapping disease co-occurrence in relation to various agrarian economic practices and socioenvironmental variables across the Brazilian Amazon. By integrating epidemiological data with land use, climatic, and demographic information, the researchers constructed a multifaceted framework to explore how agricultural modalities and human livelihood strategies modulate disease dynamics.
One of the most compelling insights emerging from this research is the pivotal role agrarian economies play in shaping vector habitats and human-vector interactions. Agricultural activities, ranging from subsistence farming to extensive cattle ranching, transform the landscape in ways that can either amplify or mitigate vector proliferation. For instance, deforestation and land clearing for agriculture often create breeding grounds for mosquitoes by generating stagnant water pools, while simultaneously disrupting natural predator populations that help control vector species.
Moreover, the socioeconomic context of rural communities—encompassing aspects such as housing quality, access to healthcare, education levels, and income—profoundly influences vulnerability to vector-borne diseases. Poor infrastructure and limited resources hinder effective disease prevention and treatment, escalating the risk of infection and complicating public health responses. The researchers underscore that social inequities intersect with environmental changes to intensify disease co-occurrence, reinforcing the notion that health outcomes in the Amazon cannot be disentangled from broader societal patterns.
Importantly, the co-occurrence of multiple vector-borne diseases in the same geographic and demographic spaces introduces unique challenges for surveillance, diagnosis, and management. Overlapping symptomatology and co-infection potential complicate clinical decision-making, while co-transmission by shared or distinct vector species demands integrated vector control strategies. The study’s nuanced approach highlights how tailored interventions must consider the local agrarian economies and socioenvironmental backdrops to effectively disrupt transmission cycles.
The analysis further integrates spatial-temporal modeling techniques to detect hotspots of disease co-occurrence. These mathematical and computational models, employing advanced geostatistical methods, reveal dynamic patterns aligning with seasonal changes, land-use shifts, and population movements. Such data-driven insights facilitate the prioritization of resources toward areas most susceptible to simultaneous outbreaks, providing a robust tool for public health planning.
Beyond pointing out correlations, the researchers propose mechanisms by which agrarian economies precipitate ecological alterations favoring vector adaptation. For example, cattle ranching often promotes water storage and drainage systems, which inadvertently become breeding sites for vector mosquitoes, while crop cultivation could affect microclimate conditions conducive to vector survival. These ecological cascades underscore the need for interdisciplinary research, combining epidemiology, ecology, economics, and social sciences.
The Brazilian Amazon, a hotspot of both biodiversity and infectious diseases, thus exemplifies the intricate feedback loops between human economic activity and ecosystem health. As the global climate shifts and land-use change accelerates, understanding the socioenvironmental determinants of disease distribution assumes critical importance. This research not only advances scientific comprehension but also has major policy implications—highlighting sustainable agricultural practices and socioeconomic improvements as dual levers to reduce the burden of vector-borne diseases.
The possibility of co-infections and their synergistic effects on morbidity is another hallmark finding. Patients living in agrarian settings characterized by poverty and environmental degradation often face exposure to multiple pathogens simultaneously. The immune system’s response to co-infection may alter disease severity and treatment outcomes, posing a public health conundrum that demands integrated diagnostic approaches and targeted therapies.
Encouragingly, the research paves the way for community-based participatory strategies that align disease control with livelihood enhancement. Recognizing local knowledge and integrating agricultural best practices with vector management can potentiate sustainable interventions. For example, modifying irrigation practices to minimize stagnant water or improving housing conditions can substantially reduce vector habitats while supporting agricultural productivity.
Sustainability emerges as a key theme, emphasizing that controlling vector-borne disease co-occurrence transcends medical interventions. Policies fostering economic diversification, education, and infrastructure development are integral to disrupting the pervasive cycles of infection. The researchers advocate for cross-sector collaboration encompassing health agencies, agricultural planners, environmental managers, and local stakeholders to forge resilient systems adaptable to evolving ecological and social landscapes.
As Brazil grapples with competing pressures of economic development and environmental conservation, this research underscores the necessity of nuanced approaches that balance agrarian growth with health. It reveals that unchecked agrarian expansion without attention to socioenvironmental variables could exacerbate disease risks, indicating a path toward integrated, eco-health oriented policy frameworks.
The study also calls attention to the potential impact of climate variability, which synergizes with agrarian and socioenvironmental factors to influence vector ecology. Changes in precipitation, temperature, and seasonality may alter the geographic range and population dynamics of vectors, further complicating disease control. This underscores the urgency for adaptive monitoring systems that incorporate climatic data to anticipate and mitigate emerging threats.
In conclusion, this pioneering research presents an intricate tapestry of how agrarian economies and socioenvironmental contexts shape vector-borne disease co-occurrence in the Brazilian Amazon. By weaving together ecological, economic, and social threads, it provides a powerful lens through which to understand and address infectious disease challenges in one of the world’s most complex biomes. The implications reach far beyond the Amazon, offering global lessons in navigating the nexus of agriculture, environment, and health in a rapidly changing world.
Subject of Research: Vector-borne disease co-occurrence influenced by agrarian economy and socioenvironmental contexts in the Brazilian Amazon
Article Title: Vector-borne disease co-occurrence is shaped by agrarian economy and socioenvironmental contexts in the Brazilian Amazon
Article References:
Barbosa, M., Lana, R.M., Dal’Asta, A.P. et al. Vector-borne disease co-occurrence is shaped by agrarian economy and socioenvironmental contexts in the Brazilian Amazon. Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-03619-4
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