The Amazon rainforest as a cloud machine: How thunderstorms and plant transpiration produce condensation nuclei

Two studies with the participation of Goethe University Frankfurt, Max Planck Institute for Chemistry, University of Helsinki, and Leibniz Institute for Tropospheric Research, and Brazilian partner institutions, shed light on new climate mechanism

Goethe University Frankfurt

 

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Heavy showers occur over the rainforest again and again.

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Credit: Philip Holzbeck, MPI for Chemistry, Germany

FRANKFURT/MAINZ/HELSINKI/LEIPZIG. Who hasn’t enjoyed the aromatic scent in the air when walking through the woods on a summer’s day? Partly responsible for this typical smell are terpenes, a group of substances found in tree resins and essential oils. The primary and most abundant molecule is isoprene. Plants worldwide are estimated to release 500 to 600 million tons of isoprene into the surrounding atmosphere each year, accounting for about half the total emissions of gaseous organic compounds from plants. “The Amazon rainforest alone is responsible for over a quarter of these emissions,” explains atmospheric researcher Professor Joachim Curtius from Goethe University Frankfurt.

So far, it was thought that the isoprene in the Amazon basin degrades rapidly and does not reach higher atmospheric layers. This is because hydroxyl radicals form in the atmosphere close to the ground during the day when the sun shines. They are highly reactive and destroy the isoprene molecules within hours. “However, we have now established that this is only partly true,” says Curtius. “There are still considerable amounts of isoprene in the rainforest at night, and a substantial proportion of these molecules can be transported to higher atmospheric layers.”

Thunderstorms act like vacuum cleaners

Responsible for this are tropical thunderstorms that brew over the rainforest at night. They pull the isoprene up like a vacuum cleaner and transport it to an altitude of between 8 and 15 kilometers. As soon as the sun rises, hydroxyl radicals form, which react with the isoprene. But at the extremely low temperatures that prevail at these high altitudes, the rainforest molecules are transformed into compounds different from those near the ground. They bind with nitrogen oxides produced by lightning during the thunderstorm. Many of these molecules can then cluster to form aerosol particles of just a few nanometers. These particles, in turn, grow over time and then serve as condensation nuclei for water vapor – they thus play an important role in cloud formation in the tropics.

“We were able to shed light on these processes with the help of research flights that started two hours before sunrise and then continued through the day,” explains Professor Jos Lelieveld. He is director at the Max Planck Institute for Chemistry in Mainz and also head of the CAFE-Brazil research project (Chemistry of the Atmosphere: Field Experiment in Brazil), in which an international research team was collecting data on the chemical processes in the atmosphere over the Amazon rainforest. “We were able to detect considerable amounts of isoprene in the air flowing out of the thunderstorms at high altitude, from which new aerosol particles rapidly formed after several chemical reactions.”

Possible influence on the cloud formation over the ocean

Curtius and Lelieveld are not only partners in CAFE-Brazil but also involved in the CLOUD consortium, in which over 20 research groups study climate-relevant chemical processes in the atmosphere. They reproduce the conditions that prevail at this altitude in the aerosol and cloud experiment chamber at CERN in Geneva. With the help of this simulation chamber, they analyze in detail which reactions are triggered by sunlight. “In this way, we were able to determine exactly the rate at which the aerosol particles form from the isoprene products,” explains atmospheric researcher Dr. Xu-Cheng He, who is in charge of the isoprene experiments. “Interestingly, it emerged that even extremely small amounts of sulfuric acid and iodine oxoacids commonly present in the atmosphere are sufficient to accelerate the formation of the aerosol particles by a factor of 100. These molecules may, therefore, jointly influence marine cloud formation – a critically uncertain process in climate projections.”

 

Sulfuric acid forms in the atmosphere from various sulfurous substances. It can result, above all, from the reaction of sulfur dioxide with hydroxyl radicals. Within the CLOUD experiment, the Frankfurt research group was responsible for measuring the extremely low concentrations of sulfuric acid, and the Mainz team measured the hydroxy radicals.

The winds that prevail at high altitudes above the Amazon rainforest can transport the particles that form from isoprene up to thousands of kilometers away from the sources. This means they may influence cloud formation at great distances. As clouds, depending on their type and height, both shield solar radiation and prevent heat from being radiated into space, they play a crucial role in the climate. The researchers, therefore, expect that their findings will contribute to improving climate models.

It also follows from the CAFE-Brazil project results that continued deforestation of the Amazon rainforest could affect the climate in two respects. “On the one hand, greenhouse gases are released because the forest no longer stores carbon dioxide,” says Curtius. “On the other hand, clearing the forest impacts both the water cycle and isoprene emissions, further propelling climate change.”

Background Information:

CAFE-Brazil: Research in and high above the Amazon rainforest (5th Dec. 2024)
https://aktuelles.uni-frankfurt.de/news-in-brief/research-in-and-high-above-the-amazon-rainforest/
https://www.mpic.de/5299698/cafe-brazil-kampagne

Ocean sunshade: How clouds influence climate change (Forschung Frankfurt 2.2021)
https://www.goethe-university-frankfurt.de/118615101.pdf

Publications:

Joachim Curtius et al.: Isoprene nitrates drive new particle formation in Amazon’s upper troposphere. Nature (2024), DOI: https://doi.org/10.1038/s41586-024-08192-4

Jiali Shen et al.: New particle formation from isoprene in the upper troposphere. Nature (2024), DOI:  https://doi.org/10.1038/s41586-024-08196-0

roject’s research aircraft shortly after take-off.

Credit

Dirk Dienhart, MPI for Chemistry

The Rio Negro in the Amazon basin as seen from the research aircraft.

Credit

Linda Ort, MPI for Chemistry, Germany

Clouds over the Amazon basin, taken during a research flight.

The instruments and measurement data are checked on board the research aircraft by scientists Gabriela Unfer (left) and Zaneta Hamryszczak.

Credit

Philip Holzbeck, MPI for Chemistry, Germany

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Journal

Nature

DOI

10.1038/s41586-024-08192-4 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Isoprene nitrates drive new particle formation in Amazon’s upper troposphere

Article Publication Date

4-Dec-2024

Rainforest emissions linked with new particle formation at high altitudes

Recent research has identified that isoprene, a naturally occurring organic compound emitted by vegetation, significantly contributes to the formation of new particles in the upper troposphere. These findings enhance our understanding of atmospheric process

University of Helsinki

 

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With experiments performed in the CLOUD chamber at CERN, researchers aimed to determine whether isoprene oxygenated organic molecules could form new particles under upper-tropospheric conditions. Xu-Cheng He, Jiali Shen and Katrianne Lehtipalo in CERN.

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Credit: Xu-Cheng He

Why are there so many newly formed aerosol particles in the upper troposphere over tropical regions such as the Amazon? Tropical forests play an important role in global climate regulation; however, the high concentrations of new particles above these areas have puzzled atmospheric scientists for the past 20 years.

An international study, led by researchers at the University of Helsinki, shows that the answer may be isoprene. Isoprene is the most abundant non-methane hydrocarbon emitted into the atmosphere, primarily by vegetation.

The study, just published in Nature, investigated the formation of new particles from isoprene in the upper troposphere. The troposphere is the lowest layer of the atmosphere, spanning from ground level to an altitude of 18 km at the equator. With experiments performed in the CLOUD chamber at CERN, researchers aimed to determine whether isoprene oxygenated organic molecules (IP-OOM), which are compounds that form when isoprene is oxidized in the atmosphere, could form new particles under upper-tropospheric conditions such as temperatures below -30°C.

They also explored how factors, such as temperature, the presence of trace acids, and nitrogen oxides, affect this process.

Isoprene can drive rapid particle formation

The researchers found that isoprene oxygenated organic molecules can rapidly form new particles under upper-tropospheric conditions. Previously, isoprene was thought to have negligible ability to form particles; however, this study showed that isoprene can drive rapid particle formation under certain conditions.

“Our key finding is that the presence of extremely low concentrations of sulphuric acid or iodine oxoacids dramatically enhances particle formation, accelerating it up to 100 times faster compared to when only isoprene oxygenated organics are present. These findings can explain the high particle number concentrations observed at high altitudes over tropical regions such as the Amazon”, explains Jiali Shen, postdoctoral researcher at the Institute for Atmospheric and Earth System Research (INAR), University of Helsinki.

Increasing understanding of cloud formation and climate

Aerosol particles are important for the climate because they scatter and absorb incoming solar radiation and seed cloud droplets by acting as cloud condensation nuclei. These newly published findings could have significant implications for our understanding of cloud formation and climate.

“This research connects the abundant isoprene emissions from tropical rainforests to particle formation in the upper troposphere, highlighting a new aspect of the interaction between forests and the atmosphere. These results may lead to improvements in atmospheric chemistry and climate models, potentially enhancing our ability to predict climate change and its impacts”, says Xu-Cheng He, one of the lead investigators in the study.

“This study underscores the complex interactions between forests, the atmosphere, and climate. This demonstrates how emissions from trees can have far-reaching effects on cloud formation and potentially on the global climate. This type of fundamental research is crucial for improving our understanding of climate processes and our ability to predict and mitigate climate change”, says Professor Katrianne Lehtipalo from the University of Helsinki.

Schematic of new particle formation from isoprene in the upper troposphere. Isoprene emitted by forests is efficiently transported to the upper troposphere at night via deep convective clouds. During daylight, the oxidation products of isoprene drive the formation of high particle number concentrations, which subsequently influence cloud formation and climate.

Credit

Xu-Cheng He

Journal

Nature

DOI

10.1038/s41586-024-08196-0 

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

New particle formation from isoprene under upper-tropospheric conditions

Article Publication Date

4-Dec-2024

 OUTLAW PALM OIL

After decades of plantation agriculture, coconut palms dominate over half of Pacific atoll forests

University of California - Santa Barbara

 

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Seabirds like these red-footed boobies do not nest in coconut palms, so the reduction of broadleaf forests would deprive the atoll of the nutrients from their droppings.

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Credit: Kydd Pollock, The Nature Conservancy

(Santa Barbara, Calif.) — Coconut palms are king throughout the tropics, serving as the foundation for human lives and cultures across the Pacific Ocean for centuries. However, 200 years of planting by colonial interests transformed the palm from the revered “Tree of Life” to a cash crop monoculture grown on Pacific atolls for a singular purpose — production of coconut oil (copra) for export around the world.

Despite wide interest in the global footprint of palm crops, the distribution of coconut palms across tropical Pacific atolls has received little attention. Until now. Published in Environmental Research Letters, research from UC Santa Barbara and The Nature Conservancy provides the first comprehensive map of the vast footprint of coconut palm agriculture across nearly every Pacific atoll.

“Coconut oil used to be essential to atoll economies, but today most coconut palm plantations are abandoned and overgrown,” said lead author Michael Burnett, a doctoral student in UCSB’s Department of Ecology, Evolution, and Marine Biology. “With the growing climate threats facing Pacific atolls, it's critical to figure out where these abandoned plantations are using up critical land and water resources, and where there may be opportunities to restore the native forests to the benefit of islands and islanders.”

Coconut palms now represent over half of the tree cover on these low islands, confining formerly widespread native broadleaf trees to small fractions of their natural range. “That’s a problem,” Burnett said, “because replacement of broadleaf forests with coconut monocrops has been linked to groundwater depletion, declining seabird populations, and adverse impacts on adjacent coral reefs. Understanding the present extent of coconut plantations is crucial for confronting sustainability challenges facing communities across the Pacific’s 266 atolls.”

This loss of unique ecosystems on Pacific atolls is staggering. It even exceeds the rate of deforestation due to oil palm production, at least in relative terms, in other parts of the world. For instance, 10.8% of Borneo’s land area had been converted to oil palm monocrops by 2015. Meanwhile, coconut palms presently cover 58.3% of the mapped atolls’ total forested area and 24.1% of their total land area.

What’s more, 51.2% of these coconut canopies occur in monocultures indicative of plantation agriculture and drastic ecological changes. Despite the abandonment of many plantations in recent decades, the authors found that coconut palms still surpass native broadleaf trees in terms of canopy area. Yet, forest conversion on Pacific atolls has scarcely received a fraction of the scholarly attention devoted to mapping oil palm-driven forest conversion.

“As the world comes to terms with tradeoffs associated with converting primary forest to croplands, we should not ignore atoll forests and the opportunity to recover these dynamic, resilient systems,” said Alex Wegmann, lead scientist for The Nature Conservancy’s Island Resilience Strategy and an author on the paper. “There is increasing evidence atolls play an important role in ocean health as nodes of biological connectivity and as nutrient concentrators — restoring and protecting atoll ecosystems should be an ‘ocean health’ priority.”

Fortunately, coconut palm plantations have untapped potential for ecosystem restoration, resource conservation, and climate resilience. The paper’s vegetation maps are a first step in helping Pacific atoll communities visualize the state of their forests and evaluate the potential best uses—for coconut production, broadleaf forest restoration, or any path in between.

“Coconuts and coconut trees are deeply woven into the lives and livelihoods of Pacific peoples and communities, symbolizing resilience, and sustenance” said Elizabeth Terk, Micronesia conservation director for The Nature Conservancy. “However, restoring abandoned copra plantations on atolls to native forests offer invaluable ecological benefits, such as biodiversity recovery and climate resilience. Striking a balance between cultural heritage and environmental stewardship is essential for a sustainable future. Mapping the extent of copra plantations on atolls is a crucial step for informed decision-making. Helping to provide a clearer picture of land use, enabling us to balance economic needs with ecological restoration and climate adaption efforts.”

Ecosystem management projects, including the conversion of abandoned coconut plantations to native forests and the restoration of seabird colonies, have shown great promise on atolls. Yet these are invariably multi-year endeavors, and such efforts must be pursued with urgency by local stakeholders to achieve resilience in the face of accelerating climate impacts.

“These maps,” said Burnett, “are part of a growing body of science exploring the numerous opportunities for conservation and resilience on atolls. We hope they will help atoll communities chart their own futures in an era of global change.”

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Journal

Environmental Research Letters

 

How did humans and dogs become friends? Connections in the Americas began 12,000 years ago

A University of Arizona-led study sheds light on how long humans in the Americas have had relationships with the ancestors of today's dogs – and asks an "existential question": What is a dog?

University of Arizona

 

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François Lanoë, an assistant research professor in the U of A School of Anthropology, after helping unearth this 8,100-year-old canine jawbone in interior Alaska in June 2023. The bone, along with a 12,000-year-old leg bone discovered at a nearby site, are some of the earliest evidence that ancient dogs and wolves formed close relationships with people in the Americas.

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Credit: Courtesy of Zach Smith

"Dog is man's best friend" may be an ancient cliché, but when that friendship began is a longstanding question among scientists.

A new study led by a University of Arizona researcher is one step closer to an answer on how Indigenous people in the Americas interacted with early dogs and wolves.

The study, published today in the journal Science Advances and based on archaeological remains from Alaska, shows that people and the ancestors of today's dogs began forming close relationships as early as 12,000 years ago – about 2,000 years earlier than previously recorded in the Americas.

"We now have evidence that canids and people had close relationships earlier than we knew they did in the Americas," said lead study author François Lanoë, an assistant research professor in the U of A School of Anthropology in the College of Social and Behavioral Sciences.

"People like me who are interested in the peopling of the Americas are very interested in knowing if those first Americans came with dogs," Lanoë added. "Until you find those animals in archaeological sites, we can speculate about it, but it's hard to prove one way or another. So, this is a significant contribution."

Lanoë and his colleagues unearthed a tibia, or lower-leg bone, of an adult canine in 2018 at a longstanding archeological site in Alaska called Swan Point, about 70 miles southeast of Fairbanks. Radiocarbon dating showed that the canine was alive about 12,000 years ago, near the end of the Ice Age.

Another excavation by the researchers in June 2023 – of an 8,100-year-old canine jawbone at a nearby site called Hollembaek Hill, south of Delta Junction – also shows signs of possible domestication.

The smoking gun? A belly of fish

Chemical analyses of both bones found substantial contributions from salmon proteins, meaning the canine had regularly eaten the fish. This was not typical of canines in the area during that time, as they hunted land animals almost exclusively. The most likely explanation for salmon showing up in the animal's diet? Dependence on humans.

"This is the smoking gun because they're not really going after salmon in the wild," said study co-author Ben Potter, an archaeologist with the University of Alaska Fairbanks.

The researchers are confident that the Swan Point canine helps establish the earliest known close relationships between humans and canines in the Americas. But it's too early to say whether the discovery is the earliest domesticated dog in the Americas.

That is why the study is valuable, Potter said: "It asks the existential question, what is a dog?"

The Swan Point and Hollembaek Hill specimens may be too old to be genetically related to other known, more recent dog populations, Lanoë said.

"Behaviorally, they seem to be like dogs, as they ate salmon provided by people," Lanoë said, "but genetically, they're not related to anything we know."

He noted that they could have been tamed wolves rather than fully domesticated dogs.

'We still had our companions'

The study represents another chapter in a longstanding partnership with tribal communities in Alaska's Tanana Valley, where archaeologists have worked since the 1930s, said study co-author Josh Reuther, an archaeologist with the University of Alaska Museum of the North.

Researchers regularly present their plans to the Healy Lake Village Council, which represents the Mendas Cha'ag people indigenous to the area, before undertaking studies, including this one. The council also authorized the genetic testing of the study's new specimens.

Evelynn Combs, a Healy Lake member, grew up in the Tanana Valley, exploring dig sites as a kid and taking in what she learned from archaeologists. She's known Lanoë, Potter and Reuther since she was a teenager. Now an archaeologist herself, Combs works for the tribe's cultural preservation office.

"It is little – but it is profound – to get the proper permission and to respect those who live on that land," Combs said.

Healy Lake members, Combs said, have long considered their dogs to be mystic companions. Today, nearly every resident in her village, she said, is closely bonded to one dog. Combs spent her childhood exploring her village alongside Rosebud, a Labrador retriever mix.

"I really like the idea that, in the record, however long ago, it is a repeatable cultural experience that I have this relationship and this level of love with my dog," she said. "I know that throughout history, these relationships have always been present. I really love that we can look at the record and see that thousands of years ago, we still had our companions."

Researchers unearthed this 8,100-year-old canine jawbone in interior Alaska in June 2023. The bone, along with a 12,000-year-old leg bone discovered at a nearby site, are the earliest evidence that ancestors of today's dogs formed close relationships with people in the Americas.

Credit

Courtesy of Zach Smith

The jawbone and the leg bone, seen here in a composite scan, both showed substantial contributions from salmon proteins in lab testing, leading researchers to conclude that humans had fed the fish to the dogs.

Credit

François Lanoë/University of Arizona School of Anthropology

Researchers unearthed the jawbone at a site called Hollembaek Hill, south of Delta Junction, a region where archaeologists have long done research in partnership with local tribes.

Credit

Courtesy of Joshua Reuther

Journal

Science Advances

DOI

10.1126/sciadv.ads1335 

 

Not red in tooth and claw: Teaching evolution with conflict reduction practices increases acceptance

Highly religious Christian students accepted evolution more when it was taught with conflict reduction practices

PLOS

 

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Illustration of study design for exploring the impact of conflict reducing evolution education practices on student acceptance of evolution.

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Credit: Aini et al., 2024, PLOS ONE, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

Students in biology classes accepted the theory of evolution more often when it was taught with conflict-reducing practices, including an emphasis on religious compatibility and autonomy, according to a study published December 4, 2024 in the open-access journal PLOS ONE by Rahmi Ourota Aini and Elizabeth Barnes from Middle Tennessee State University, U.S., and colleagues.

Evolution is of the foundation of biology, but currently half of the United States population rejects the idea of human evolution. One of the most important factors in the acceptance of evolution is perceived conflict between evolution and a student’s religious beliefs.

The authors of this study surveyed 6,719 college biology students in 55 courses and 14 states. In addition to assessing religiosity, they asked the students for their experiences of an instructor teaching evolution with conflict-reducing practices. For example, instructors could offer compatibility between evolution and religion, offering examples of religious leaders who accept evolution or scientists who are religious. Instructors could also reduce conflict by emphasizing the autonomy of the students—noting that it is their choice whether to accept evolution or not.

Highly religious Christian students were more likely to accept evolution when instructors emphasized the compatibility of evolution and religion. However, all students, regardless of whether they were religious or not, were more likely to accept human evolution when instructors emphasized that it was their choice to do so.

While the instructors and classes were self-selected for the study, the results suggest that conflict resolution strategies like emphasizing compatibility between religion and evolution and a student’s autonomy can increase students’ acceptance of evolution.

The authors add: “This study reinforces a growing number of research studies showing that conflict between religion and evolution is often unnecessary. College instructors can play an important role in bridging the divide. By adopting practices that reduce perceived conflict, our findings suggest that more students and the broader public can come to embrace evolution, the cornerstone of the biological sciences.”

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In your coverage please use this URL to provide access to the freely available article in PLOS ONE: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0313490

Citation: Aini RQ, Supriya K, Dunlop H, Edwards B, Maas S, Roberts J, et al. (2024) Conflict reducing practices in evolution education are associated with increases in evolution acceptance in a large naturalistic study. PLoS ONE 19(12): e0313490. https://doi.org/10.1371/journal.pone.0313490

Author Countries: U.S.

Funding: This study is funded by National Science Foundation #1818659. The funders had role in data collection.

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Journal

PLOS ONE

DOI

10.1371/journal.pone.0313490 

Method of Research

Survey

Subject of Research

Not applicable

Article Title

Conflict reducing practices in evolution education are associated with increases in evolution acceptance in a large naturalistic study

Article Publication Date

4-Dec-2024

 

Male African elephants develop distinct personality traits as they age

Wild males show consistent individual differences in aggression, dominance and friendly behavior

PLOS

 

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A lower ranking male gives a ‘trunk-to-mouth’ salute to an older, higher-ranking individual. This greeting behavior is a very important ritual that serves to reinforce relationships between bonded individuals.

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Credit: O’Connell & Rodwell, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

Male African elephants have distinct personality traits, but also adapt their behavior to suit the social context, according to a study publishing December 4, 2024, in the open-access journal PLOS ONE by Caitlin O’Connell-Rodwell at Stanford University and Harvard University Center for the Environment, Jodie L. Berezin of Utopia Scientific, U.S., and colleagues.

Many animals show consistent individual differences in behavior, sometimes described as ‘personality’ or ‘temperament’. Elephants are highly intelligent and have rich social lives, and previous research has shown that captive elephants display distinct personality types. In the wild, females spend their entire lives in their family groups, but males disperse when they reach adulthood to join looser, all-male societies governed by dominance hierarchies.

To expand our understanding of personality traits in wild elephants, researchers observed the behavior of 34 male African savannah elephants (Loxodonta africana) in Etosha National Park in Namibia between 2007 and 2011. They identified five types of behavior that were consistently different between individuals, including aggression and dominance behaviors, friendly social interactions, and self-comforting. However, the elephant’s behavior was also influenced by the social context. When younger males were present, other males were more likely to perform friendly and dominance behaviors.

In contrast, when a socially influential male was present, the other males performed fewer friendly social interactions. The most dominant and socially influential male elephants in the society performed aggressive and friendly social behaviours equally frequently. Younger males were more similar in temperament than older males, suggesting that their unique personalities develop as they age.

The study is the first to show that adult male elephants display distinct personality traits in the wild. Although they showed consistency over time, male elephants were also flexible, adjusting their behavior depending on the social context. The results also suggest that the most socially successful male elephants are those that strike a balance between aggression and friendliness, and that having mixed age groups within male elephant populations was extremely important to their wellbeing. A deeper understanding of wild elephant behavior could inform better conservation decision-making and improve the management of captive elephants, the authors say.

The authors add: “Male elephants display five distinct character traits (affiliative, aggressive, dominant, anxious, and calm) consistently across time and context, and are also distinct from each other in how they display these five character-traits.”

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In your coverage please use this URL to provide access to the freely available article in PLOS ONE: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0311780

Citation: O’Connell-Rodwell CE, Berezin JL, Kinzley C, Freeman PT, Sandri MN, Kieschnick D, et al. (2024) Consistency and flexibility of character in free-ranging male African elephants across time, age, and social contexts. PLoS ONE 19(12): e0311780. https://doi.org/10.1371/journal.pone.0311780

Author Countries: U.S.

Funding: Field work for this research was funded by Utopia Scientific Donor Volunteers and anonymous donors (support to CEO, JLB, CK, PTF, MNS, TCR). Specific individual support was provided by the Stanford University Vice Provost Office for Undergraduate Education Faculty and Student Grants (grants to CEO, PTF), the Smith College Horner Fund Endowment (grant to JLB), as well as the Oakland Zoo Conservation Fund (grant to CK and zoo volunteers). The Elephant Sanctuary provided salary support for the analysis of data related to this study (to MNS), as well as currently providing financial support for field work and sanctuary interns (to CEO and sanctuary employees). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Journal

PLOS ONE

DOI

10.1371/journal.pone.0311780 

Method of Research

Observational study

Subject of Research

Animals

Article Title

Consistency and flexibility of character in free-ranging male African elephants across time, age, and social contexts

Article Publication Date

4-Dec-2024

Study reveals mammoth as key food source for ancient Americans

University of Alaska Fairbanks

 

image: 

An artist’s reconstruction of Clovis life 13,000 years ago shows the Anzick-1 infant with his mother consuming mammoth meat near a hearth. Another individual crafts tools, including dart projectile points and atlatls. A mammoth butchery area is visible nearby. The scene is inspired by the La Prele mammoth site in Wyoming and set against the Montana landscape where the Anzick burial was discovered. 

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Credit: Artist Eric Carlson created the scene in collaboration with archaeologists Ben Potter (UAF) and Jim Chatters (McMaster University).

Scientists have uncovered the first direct evidence that ancient Americans relied primarily on mammoth and other large animals for food. Their research sheds new light on both the rapid expansion of humans throughout the Americas and the extinction of large ice age mammals.

The study, featured on the Dec. 4 cover of the journal Science Advances, used stable isotope analysis to model the diet of the mother of an infant discovered at a 13,000-year-old Clovis burial site in Montana. Before this study, prehistoric diet was inferred by analyzing secondary evidence, such as stone tools or the preserved remains of prey animals. 

The findings support the hypothesis that Clovis people specialized in hunting large animals rather than primarily foraging for smaller animals and plants. 

The Clovis people inhabited North America around 13,000 years ago. During that time period, animals like mammoths lived across both northern Asia and the Americas. They migrated long distances, which made them a reliable fat- and protein-rich resource for highly mobile humans. 

“The focus on mammoths helps explain how Clovis people could spread throughout North America and into South America in just a few hundred years,” said co-lead author James Chatters of McMaster University.

“What's striking to me is that this confirms a lot of data from other sites. For example, the animal parts left at Clovis sites are dominated by megafauna, and the projectile points are large, affixed to darts, which were efficient distance weapons,” said co-lead author Ben Potter, an archaeology professor at the University of Alaska Fairbanks. 

Hunting mammoths provided a flexible way of life, Potter said. It allowed the Clovis people to move into new areas without having to rely on smaller, localized game, which could vary significantly from one region to the next. 

“This mobility aligns with what we see in Clovis technology and settlement patterns,” Potter said. “They were highly mobile. They transported resources like toolstone over hundreds of miles.”

Researchers were able to model the Clovis people’s diet by first analyzing isotopic data published during earlier studies by other researchers of the remains of Anzick-1, an 18-month-old Clovis child. By adjusting for nursing, they were able to estimate values for his mother’s diet. 

“Isotopes provide a chemical fingerprint of a consumer's diet and can be compared with those from potential diet items to estimate the proportional contribution of different diet items,” said Mat Wooller, an author on the study and director of the Alaska Stable Isotope facility at UAF.

The team compared the mother’s stable isotopic fingerprint to those from a wide variety of food sources from the same time period and region. They found that about 40% of her diet came from mammoth, with other large animals like elk and bison making up the rest. Small mammals, sometimes thought to have been an important food source, played a very minor role in her diet.

Finally, the scientists compared the mother’s diet to those of other omnivores and carnivores from the same time period, including American lions, bears and wolves. The mother’s diet was most similar to that of the scimitar cat, a mammoth specialist.

Findings also suggest that early humans may have contributed to the extinction of large ice age animals, especially as environmental changes reduced their habitats.

“If the climate is changing in a way that reduces the suitable habitat for some of these megafauna, then it makes them potentially more susceptible to human predation. These people were very effective hunters,” said Potter. 

“You had the combination of a highly sophisticated hunting culture — with skills honed over 10,000 years in Eurasia — meeting naïve populations of megafauna under environmental stress,” said Chatters.

An important aspect of this research, according to Potter and Chatters, is their outreach to Native Americans in Montana and Wyoming about their concerns and interest in this work. 

"It is important and ethical to consult with Indigenous peoples on questions relating to their heritage," they said. 

They worked with Shane Doyle, executive director of Yellowstone Peoples, who reached out to numerous tribal government representatives throughout Montana, Wyoming and Idaho. “The response has been one of appreciative consideration and inclusion,” said Doyle.

"I congratulate the team for their astounding discovery about the lifeways of Clovis-era Native people and thank them for being tribally inclusive and respectful throughout their research,” he said. “This study reshapes our understanding of how Indigenous people across America thrived by hunting one of the most dangerous and dominant animals of the day, the mammoth." 

Other authors of the paper include Stuart J. Fiedel, independent researcher; Juliet E. Morrow, University of Arkansas; and Christopher N. Jass, Royal Alberta Museum.

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Journal

Science Advances

DOI

10.1126/sciadv.adr3814 

Article Title

Mammoth featured heavily in Western Clovis diet

Article Publication Date

4-Dec-2024