Wednesday, January 10, 2024

More than 900 chemicals, many found in consumer products and the environment, display breast-cancer causing traits

New study advances understanding of how endocrine disrupting chemicals influence breast cancer risk

SILENT SPRING INSTITUTE

With tens of thousands of synthetic chemicals on the market, and new ones in development all the time, knowing which ones might be harmful is a challenge both for the federal agencies that regulate them and the companies that use them in products. Now scientists have found a quick way to predict if a chemical is likely to cause breast cancer based on whether the chemical harbors specific traits.

“This new study provides a roadmap for regulators and manufacturers to quickly flag chemicals that could contribute to breast cancer in order to prevent their use in consumer products and find safer alternatives,” says lead author Dr. Jennifer Kay, a research scientist at Silent Spring Institute.

Breast cancer remains the most commonly diagnosed cancer in the United States. Recent data show rates increasing in young women, a trend that can’t be explained by genetics. “We need new tools to identify environmental exposures that could be contributing to this trend so we can develop prevention strategies and reduce the burden of the disease,” says Kay.

Hormone signals

Kay and her colleagues searched through multiple international and U.S. government databases to identify chemicals that have been found to cause mammary tumors in animals. The databases were from the International Agency for Cancer Research (IARC), the National Toxicology Program, the U.S. Environmental Protection Agency (EPA), and the National Cancer Institute, among others.

The researchers also looked at data from EPA’s ToxCast program to identify chemicals that alter the body’s hormones, or endocrine disruptors, in ways that could promote breast cancer. The team looked specifically for chemicals that activate the estrogen receptor—a receptor present in breast cells—as well as chemicals that cause cells to make more estrogen or progesterone, an established risk factor for breast cancer.

Reporting in Environmental Health Perspectives, the researchers identified a total of 921 chemicals that could promote the development of breast cancer. Ninety percent of the chemicals are ones that people are commonly exposed to in consumer products, food and drink, pesticides, medications, and workplaces.

A breakdown of the list revealed 278 chemicals that cause mammary tumors in animals. More than half of the chemicals cause cells to make more estrogen or progesterone, and about a third activate the estrogen receptor. “Breast cancer is a hormonal disease, so the fact that so many chemicals can alter estrogen and progesterone is concerning,” says Kay.

Since damage to DNA can also trigger cancer, the researchers searched additional databases and found 420 of the chemicals on their list both damage DNA and alter hormones, which could make them riskier. What’s more, the team’s analysis found that chemicals that cause mammary tumors in animals are more likely to have these DNA damaging and hormone-disrupting characteristics than ones that don’t.

“Historically, chemicals that cause mammary tumors in animals were seen as the best predictor of whether they might cause breast cancer in humans,” says co-author Ruthann Rudel, director of research at Silent Spring. “But animal studies are expensive and time consuming, which is why so many chemicals have not been tested. Our findings show that screening chemicals for these hormonal traits could be an effective strategy for flagging potential breast carcinogens.”

A roadmap for safety

Over the past decade, there has been growing evidence that environmental chemicals are important contributing factors in the development of cancer. A number of studies in people have found links between breast cancer and pesticides, hair dyes, and air pollution. Other studies suggest exposure to hormone-disrupting chemicals early in life, in the womb or during puberty, can alter breast development in ways that could increase the risk of cancer later on.

To observe those associations, however, scientists have to wait until hundreds or thousands of children and women have been exposed to a chemical and check, often many years later, to see who develops breast cancer. “It’s not feasible, nor is it ethical, to wait that long,” says Rudel. “And it’s another reason why we need better tools for predicting which chemicals are likely to lead to breast cancer so we can avoid those exposures.”

The Silent Spring study could have implications for how EPA assesses chemicals for safety. For instance, the chemicals identified in the study include more than 30 pesticides that EPA previously approved for use despite evidence linking the chemicals with mammary tumors.

This fall, EPA proposed a new strategic plan to ensure that pesticides are evaluated for their effects on hormones. The study authors hope their new comprehensive list of breast cancer-relevant chemicals, which includes hundreds of endocrine disruptors, will inform EPA’s plan and better protect the public from harmful exposures.

Additional co-authors of the new study include Megan Schwarzman at UC Berkeley and Julia Brody at Silent Spring Institute.

Funding for this project was provided by the California Breast Cancer Research Program (Grant #23QB-1881) and charitable donations to the Safer Chemicals Program at Silent Spring Institute.

Reference:

Kay, J.E., J.G. Brody, M. Schwarzman, R.A. Rudel. 2023. Application of the Key Characteristics framework to identify potential breast carcinogens using publicly available in vivo, in vitro, and in silico data. Environmental Health Perspectives. DOI: 10.1289/EHP13233

JOURNAL

Environmental Health Perspectives

DOI

10.1289/EHP13233

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Cells

ARTICLE TITLE

Application of the Key Characteristics framework to identify potential breast carcinogens using publicly available in vivo, in vitro, and in silico data

ARTICLE PUBLICATION DATE

10-Jan-2024

COI STATEMENT

Silent Spring Institute is a scientific research organization dedicated to studying environmental factors in women’s health. The institute is a 501(c)3 public charity funded by federal grants and contracts, foundation grants, and private donations, including from breast cancer organizations. Study funders had no role in study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication.

FOREVER CHEMICALS

PFAS flow equally between Arctic Ocean and Atlantic Ocean, study finds

Peer-Reviewed Publication

AMERICAN CHEMICAL SOCIETY

PFAS flow equally between Arctic Ocean and Atlantic Ocean, study finds — IMAGE:
PFAS COME AND GO BETWEEN THE ARCTIC AND ATLANTIC OCEANS AT ROUGHLY EQUAL RATES.
view more
CREDIT: ADAPTED FROM ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS 2024, DOI: 10.1021/ACS.ESTLETT.3C00835

The frigid Arctic Ocean is far removed from the places most people live, but even so, “forever chemicals” reach this remote landscape. Now, research in ACS’ Environmental Science & Technology Letters suggests that per- and polyfluoroalkyl substances (PFAS) won't stay there indefinitely. Instead, they are transported in a feedback loop, with the Arctic Ocean potentially exporting as many PFAS to the North Atlantic Ocean as it receives, circulating the compounds around the world.

To get to the Arctic Ocean, some PFAS hitch a ride in the air and fall onto the ocean’s surface, but others enter from adjacent oceans. The potential impact of these compounds on marine organisms depends on what PFAS are present and how much, which are ever-changing as water flows between the Arctic Ocean and the North Atlantic Ocean. These waterbodies are connected by the Fram Strait, which sits to the northeast of Greenland near the Svalbard archipelago. Warm water travels north on the eastern side of the strait, and cold water flows south along the western side, providing a dynamic gateway for PFAS transportation. So, Rainer Lohmann and colleagues wanted to track the movement of PFAS in this region and identify how water circulation influences the mix of contaminants in the Arctic Ocean.

The researchers deployed passive sampling systems, which took up PFAS into a sorbent-filled microporous membrane from water as it flowed past. They put the systems at three locations in the Fram Strait, and at four depths in each location. After a year, the team retrieved the systems and measured the collected PFAS using liquid chromatography-mass spectrometry. The researchers overserved that:

Ten PFAS were detected in at least one passive sampler, however, one substance detected in the area by previous research teams wasn’t among them.
Two compounds known as PFOA and PFOS, which are being phased out, were present at the highest levels. Newer, short-chain PFAS were also routinely present.
Surprisingly, several PFAS were found in water below 3,000 feet deep. The team suggests that these compounds could have gotten there by attaching to particles as they fell to the seafloor.

The team calculated the amounts of PFAS flowing in each direction through the Fram Strait. Their data showed that in one year around 123 tons traveled into the Arctic Ocean and about 110 tons moved into the Atlantic Ocean. According to the researchers, these values are the largest of any pollutant reported in the strait, demonstrating how significant the back-and-forth circulation of PFAS is in the Arctic Ocean.

The authors acknowledge funding from the University of Rhode Island Sources, Transport, Exposure and Effects of PFAS (STEEP) Superfund Center, and the Alfred Wegener Institute Long Term Ecological Research Hausgarten program.

The paper’s abstract will be available on Jan. 10 at 8 a.m. Eastern time here: http://pubs.acs.org/doi/abs/10.1021/acs.estlett.3c00835

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The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

To automatically receive news releases from the American Chemical Society, contact newsroom@acs.org.

Note: ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies.

JOURNAL

Environmental Science & Technology Letters

DOI

10.1021/acs.estlett.3c00835

ARTICLE TITLE

Passive Sampler Derived Profiles and Mass Flows of Perfluorinated Alkyl Substances (PFASs) across the Fram Strait in the North Atlantic

ARTICLE PUBLICATION DATE

10-Jan-2024

Nafion byproduct 2 found in blood of well users near Fayetteville, NC

Peer-Reviewed Publication

NORTH CAROLINA STATE UNIVERSITY

Researchers from the GenX Exposure Study detected PFAS originating from a fluorochemical manufacturing plant – including Nafion byproduct 2 and GenX – in nearby private wells in Bladen and Cumberland Counties, N.C. PFAS refers to a group of chemicals called per- and polyfluoroalkyl substances.

“These compounds were released to the environment through air and wastewater emissions from the facility,” says Nadine Kotlarz, research scholar in the department of biological sciences at North Carolina State University, member of NC State’s Center for Human Health and the Environment (CHHE), and corresponding author of the paper.

“Air released from the facility caused the contamination of groundwater and private wells,” Kotlarz says. “In order to study how exposure to these chemicals may affect human health, we need to know the exposure levels across impacted people.”

In February 2019, the researchers recruited 153 people from this region who used 84 private wells to participate in the GenX Exposure Study. The participants lived within six miles of the fluorochemical facility. The participants provided well water and blood samples and filled out questionnaires about their well-water consumption.

The water and blood samples were screened for nine PFAS produced by the facility, including GenX and Nafion byproduct 2.

The PFAS found most frequently and at the highest concentrations in the wells included several low molecular weight PFAS (PMPA, PEPA, GenX, PFO2HxA, PFMOAA). The median concentration of GenX in the wells was 107 nanograms per liter (ng/L), 10 times higher than the U.S. Environmental Protection Agency’s (EPA) drinking water health advisory level of 10 ng/L.

However, these PFAS were not frequently detected in the private well users’ blood, even though they drank the well water.

Nafion byproduct 2, a higher molecular weight PFAS with a longer half-life, was detected frequently in wells at lower concentrations (the median concentration was 14 ng/L) and detected in more than half of participants’ blood.

“With Nafion byproduct 2, we saw that higher well-water concentration and the longer a person lived at their home correlated with higher blood levels,” Kotlarz says. “Well-water consumption is having an impact on exposure, and we know that several other PFAS were present in the wells, but due to the short half-lives of some PFAS (like GenX) in the body, we didn’t find all of the well water PFAS in blood.

“Blood levels of a chemical across a population are often used to characterize exposure,” Kotlarz says. “Without blood levels, we will need to estimate exposure to PFAS such as GenX another way in order to study their potential health effects.”

The research appears in the Journal of Exposure Science and Environmental Epidemiology. The GenX Exposure Study is supported by research funding from the National Institute of Environmental Health Sciences (1R21ES029353), NC State’s CHHE (P30 ES025128), the Center for Environmental and Health Effects of PFAS (P42 ES0310095), and the NC Policy Collaboratory. James McCord and Mark Strynar from the EPA; David Collier and Suzanne Lea from East Carolina University; Theresa Guillette of the Oak Ridge Institute for Science and Education Research; and Claire Critchley, Michael Cuffney, Zachary Hopkins, Detlef Knappe and Jane Hoppin of NC State also contributed to the work.

-peake-

Note to editors: An abstract follows.

“Per- and polyfluoroalkyl ether acids in well water and blood serum from private well users residing by a fluorochemical facility near Fayetteville, North Carolina”

DOI: 10.1038/s41370-023-00626-x

Authors: Nadine Kotlarz, Claire Critchley, Michael Cuffney, Zachary R. Hopkins, Detlef R.U. Knappe, Jane A. Hoppin, North Carolina State University; Theresa Guillette, Oak Ridge Institute for Science and Education Research; David Collier, C. Suzanne Lea, East Carolina University; James McCord, Mark Strynar, U.S. Environmental Protection Agency
Published: Jan. 10, 2024 in the Journal of Exposure Science and Environmental Epidemiology

Abstract:
BACKGROUND: A fluorochemical facility near Fayetteville, North Carolina, emitted per- and polyfluoroalkyl ether acids (PFEAs), a subgroup of per- and polyfluoroalkyl substances (PFAS), to air.
OBJECTIVE: Analyze PFAS in private wells near the facility and in blood from well users to assess relationships between PFEA levels in water and serum.
METHODS: In 2019, we recruited private well users into the GenX Exposure Study and collected blood and well water samples. We targeted 26 PFAS (11 PFEAs) in water and 27 PFAS (9 PFEAs) in serum using liquid chromatography-mass spectrometry. We used regression modeling to explore relationships between water and serum PFAS. For the only PFEA detected frequently in water and serum, Nafion byproduct 2, we used generalized estimating equation (GEE) models to assess well water exposure metrics and then adjusted for covariates that may influence Nafion byproduct 2 serum concentrations.
RESULTS: We enrolled 153 participants ages 6 and older (median=56 years) using 84 private wells. Most wells (74%) had ≥6 detectable PFEAs; median ∑PFEAs was 842 ng/L (interquartile range=197-1,760 ng/L). Low molecular weight PFEAs (PMPA, HFPO-DA [GenX], PEPA, PFO2HxA) were frequently detected in well water, had the highest median concentrations, but were not detectable in serum. Nafion byproduct 2 was detected in 73% of wells (median=14 ng/L) and 56% of serum samples (median=0.2 ng/mL). Cumulative dose (well concentration × duration at address) was positively associated with Nafion byproduct 2 serum levels and explained the most variability (10%). In the adjusted model, cumulative dose was associated with higher Nafion byproduct 2 serum levels while time outside the home was associated with lower levels.
SIGNIFICANCE: Serum biomarkers were not good measures of long-term exposure to low molecular weight PFEAs in a private well population. For Nafion byproduct 2, well water exposure metrics were associated with serum levels, particularly when incorporating exposure duration.

JOURNAL

Journal of Exposure Science & Environmental Epidemiology

DOI

10.1038/s41370-023-00626-x

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Per- and polyfluoroalkyl ether acids in well water and blood serum from private well users residing by a fluorochemical facility near Fayetteville, North Carolina

ARTICLE PUBLICATION DATE

10-Jan-2024

Nine new snail species discovered in Papua New Guinea, a biodiversity hot spot at risk

Peer-Reviewed Publication

FLORIDA MUSEUM OF NATURAL HISTORY

Nine new species of carnivorous land snails have been found in the remote forests of Papua New Guinea, a biodiversity hot spot. A new study describes the species, which are so small that all nine could fit together on a U.S. nickel. They present a rare opportunity to study a group that in many other places is disappearing fast. Worldwide, mollusks account for more than 50% of all recorded extinctions since the year 1500, and many of these were land snails from Pacific islands.

The island of New Guinea accounts for less than 1% of Earth’s land area, but it contains roughly 5% of the planet’s biodiversity and the largest intact rainforests in Australasia. Wildlife thrives within this large swath of undeveloped land, but Papua New Guinea’s old-growth forests are also highly desirable to loggers and are likely to become a conservation battleground in the future.

“These new species of snails were found in areas that still have native vegetation and still appear to be doing well, but they could easily become endangered if things change,” said John Slapcinsky, lead author of the paper and manager of the Florida Museum’s invertebrate zoology collection.

To reach Papua New Guinea's isolated forests, researchers had to travel on foot over steep mountains, sometimes using fallen trees to cross crevices that were more than 100 feet deep. There are few roads in the country, which historically posed a challenge to scientists interested in researching the region but has also shielded native plants and animals from human disturbance and habitat destruction.

Slapcinsky took nine trips to Papua New Guinea between 2002 and 2012, each time staying for at least a month to comb through the soil and fallen leaves. He ultimately collected more than 19,000 snails from over 200 sites.

Only 31% of the snail species he surveyed had been previously documented, a sign of Papua New Guinea’s high biodiversity and low levels of sampling. But the snails are also exceptionally hard to find because of their small size, pickiness about their habitats and limited distribution. Nearly all of them are restricted to a single island or mountain.

The newly named snails have tightly coiled, Frisbee-shaped shells in various shades of brown and tan, some with attractive gold or brown flamelike bands. One of the new species, Torresiropa paterivolans, was named for its resemblance to flying saucers (in Latin, “patera” means “saucer,” and “volans” means “flying”).

All nine species have dagger-shaped teeth on their radula, which is characteristic of predatory snails. Just what they’re eating, Slapcinsky said, is a mystery, since the snails did not eat anything under observation. Still, the shape of the teeth, combined with the fact that other species in the same family — Rhytididae — are predators, suggests that these newly discovered snails do eat meat.

There is not yet enough data to know the conservation status of the new species, but it is a promising sign that their habitat has not yet been dramatically altered by human activity.

Slapcinsky contrasted this with the Hawaiian Islands, where native snails are at imminent risk of extinction. He works with a team at the Bishop Museum in Honolulu that collaborates with the state and federal government on captive breeding programs for native snail colonies, many of which harbor the last members of their species. They also provide native snails for fenced-in areas, known as exclosures, where predators have been removed and the native forest has been replanted. These are expensive programs that Papua New Guinea still has the chance to avoid, Slapcinsky said, by slowing deforestation and preventing the introduction of non-native predators before it becomes a more serious problem.

Snails are highly vulnerable to habitat disturbances because they cannot easily travel long distances and are usually adapted only to the environment in their immediate vicinity. “When these habitats are threatened, snails are often out of luck, since they can’t go anywhere,” Slapcinsky said.

Many past discoveries of new snail species, especially on Pacific islands, have come after it was too late to save them. Scientists did not know that many snails lived on Easter Island, which was completely deforested centuries ago, until examining fossil deposits. But species on the island of New Guinea can still be saved if the forest is saved. The newly named snails provide a rare glimpse at an ecosystem that remains largely intact, and there are surely many similar discoveries yet to be made.

“We don’t know everything that’s out there,” Slapcinsky said. “Most people may not realize how poorly known most of the invertebrates are, even though 95 to 99% of all animals are invertebrates. You can go to a place, look around for a few months and find all sorts of things that haven’t been described before.”

Detailed photos of the snails, while beautiful, also serve a scientific purpose by providing documentation of the species.

CREDIT

Florida Museum photo by Jeff Gage

The country of Papua New Guinea includes the eastern half of the island of New Guinea and several offshore islands.

CREDIT

Florida Museum photo by John Slapcinsky

JOURNAL

Archiv für Molluskenkunde

DOI

10.1127/arch.moll/152/135-152

ARTICLE TITLE

Overlooked predatory snails from Papua New Guinea: nine new Torresiropa Solem, 1959 (Gastropoda: Stylommatophora: Rhytididae)

How fruit bats got a sweet tooth without sour health

Peer-Reviewed Publication

UNIVERSITY OF CALIFORNIA - SAN FRANCISCO

Levi Gadye,
Levi.Gadye@ucsf.edu | @UCSF

Video: https://ucsf.app.box.com/s/i3atd54ye4m1z1spi0qf59axq7tq7640

A high-sugar diet is bad news for humans, leading to diabetes, obesity and even cancer. Yet fruit bats survive and even thrive by eating up to twice their body weight in sugary fruit every day.

Now, UC San Francisco scientists have discovered how fruit bats may have evolved to consume so much sugar, with potential implications for the 37 million Americans with diabetes. The findings, published on Tuesday, Jan. 9, 2024 in Nature Communications, point to adaptations in the fruit bat body that prevent their sugar-rich diet from becoming harmful.

Diabetes is the eighth leading cause of death in the United States, according to the Centers for Disease Control and Prevention, and it’s responsible for $237 billion in direct medical costs each year.

“With diabetes, the human body can’t produce or detect insulin, leading to problems controlling blood sugar,” said Nadav Ahituv, PhD, director of the UCSF Institute for Human Genetics and co-senior author of the paper. “But fruit bats have a genetic system that controls blood sugar without fail. We’d like to learn from that system to make better insulin- or sugar-sensing therapies for people.”

Ahituv’s team focused on evolution in the bat pancreas, which controls blood sugar, and the kidneys. They found that the fruit bat pancreas, compared to the pancreas of an insect-eating bat, had extra insulin-producing cells as well as genetic changes to help it process an immense amount of sugar. And fruit bat kidneys had adapted to ensure that vital electrolytes would be retained from their watery meals.

“Even small changes, to single letters of DNA, make this diet viable for fruit bats,” said Wei Gordon, PhD, co-first author of the paper, a recent graduate of UCSF’s TETRAD program, and assistant professor of biology at Menlo College. “We need to understand high-sugar metabolism like this to make progress helping the one in three Americans who are prediabetic.”

A sweet tooth without consequences

Each day, after 20 hours of sleep, fruit bats wake up for four hours to gorge on fruit. Then it’s back to the roost.

To understand how a fruit bat pulls off this feat of sugar consumption, Ahituv and Gordon collaborated with scientists from a variety of institutions, ranging from Yonsei University in Korea to the American Museum of Natural History in New York City, to compare the Jamaican fruit bat to the big brown bat, which only eats insects.

The researchers analyzed gene expression (which genes were on or off) and regulatory DNA (the parts of DNA that control gene expression) using a method for measuring both in individual cells.

“This newer single-cell technology can explain not only which types of cells are in which organs, but also how those cells regulate gene expression to manage each diet,” Ahituv said.

In fruit bats, the compositions of the pancreas and kidneys evolved to accommodate their diet. The pancreas had more cells to produce insulin, which tells the body to lower blood sugar, as well as more cells to produce glucagon, the other major sugar-regulating hormone. The fruit bat kidneys, meanwhile, had more cells to trap scarce salts as they filter blood.

Zooming in, the regulatory DNA in those cells had evolved to turn the appropriate genes for fruit metabolism on or off. The big brown bat, on the other hand, had more cells for breaking down protein and conserving water. And the gene expression in those cells was tuned to handle a diet of bugs.

“The organization of the DNA around the insulin and glucagon genes was very clearly different between the two bat species,” Gordon said. “The DNA around genes used to be considered ‘junk,’ but our data shows that this regulatory DNA likely helps fruit bats react to sudden increases or decreases in blood sugar.”

While some of the biology of the fruit bat resembled what’s found in humans with diabetes, the fruit bat appeared to evolve something that humans with a sweet tooth could only dream of: a sweet tooth without consequences.

“It’s remarkable to step back from model organisms, like the laboratory mouse, and discover possible solutions for human health crises out in nature,” Gordon said. “Bats have figured it out, and it’s all in their DNA, the result of natural selection.”

Superheroes of evolution

The study benefited from a recent groundswell of interest in studying bats to better human health. Gordon and Ahituv traveled to Belize to participate in an annual Bat-a-Thon with nearly 50 other bat researchers, taking a census of wild bats as well as field samples for science. One of the Jamaican fruit bats captured at this event was used in the sugar metabolism study.

As one of the most diverse families of mammals, bats include many examples of evolutionary triumph, from their immune systems to their peculiar diets and beyond.

“For me, bats are like superheroes, each one with an amazing super power, whether it is echolocation, flying, blood sucking without coagulation, or eating fruit and not getting diabetes,” Ahituv said. “This kind of work is just the beginning.”

Key collaborators included co-first author Seungbyn Baek, PhD, from Yonsei University (South Korea); co-senior author Martin Hemberg, PhD, from Harvard Medical School; Tony Schountz, PhD, from Colorado State University; Lisa Noelle Cooper, PhD, from Northeast Ohio Medical University; Melissa R. Ingala, PhD, Fairleigh Dickinson University; and Nancy B. Simmons, PhD, American Museum of Natural History. Other UCSF authors are Hai P. Nguyen, PhD, Yien-Ming Kuo, PhD, Rachael Bradley, and Sarah L. Fong, PhD. For all authors see the paper.

About UCSF: The University of California, San Francisco (UCSF) is exclusively focused on the health sciences and is dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. UCSF Health, which serves as UCSF's primary academic medical center, includes top-ranked specialty hospitals and other clinical programs, and has affiliations throughout the Bay Area. UCSF School of Medicine also has a regional campus in Fresno. Learn more at https://ucsf.edu, or see our Fact Sheet.

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JOURNAL

Nature Communications

Orbitally-induced strong monsoons facilitated early human dispersal to East Asia

Peer-Reviewed Publication

CHINESE ACADEMY OF SCIENCES HEADQUARTERS

Field photograph of the Huanxian loess-paleosol sequence on the central Chinese Loess Plateau — IMAGE:
FIELD PHOTOGRAPH OF THE HUANXIAN LOESS-PALEOSOL SEQUENCE ON THE CENTRAL CHINESE LOESS PLATEAU
view more
CREDIT: AO HONG

In a study published in PNAS, researchers have shown that orbitally induced strengthening of the Asian summer monsoon played a key role in the dispersal of Homo sapiens from Africa to East Asia during the last interglacial period 125,000 to 70,000 years ago.

Led by Prof. AO Hong from the Institute of Earth Environment of the Chinese Academy of Sciences (CAS), the researchers integrated a comprehensive compilation of paleoanthropological site data with new high-resolution reconstructions of the Asian summer monsoon based on Chinese loess data, continuous modeling of the East Asian hydroclimate, and a novel human habitat simulation—all covering the past 280,000 years.

How human ancestors responded to past climate change remains a key question in research on human evolution. Climate variability was a key driver of human evolution and dispersal within Africa during the Pleistocene. However, our understanding of the orbital hydroclimatic influence on the early dispersal of our species, Homo sapiens, from Africa to East Asia, is hampered by the lack of integrated paleoclimatic and paleoanthropological studies from Asia.

To reconstruct orbitally resolved Asian summer monsoon variability over the past 280,000 years, the researchers collected 2,066 samples in the field from the rapidly accumulating Huanxian loess–paleosol section on the central Chinese Loess Plateau for measurements in the laboratory.

The resulting unprecedented centennial-resolution reconstructions suggest that the orbital-scale variability of the Asian summer monsoon responds to the combined action of changes in insolation (a so-called external forcing, i.e., one coming from outside Earth), and ice volume and greenhouse gas concentration (examples of what we call internal forcings, i.e., those coming from the Earth system), rather than to their individual actions. This argument is strongly supported by AO et al.'s model-based reconstructions of the East Asian hydroclimate over the past 280,000 years.

"When we integrated proxy- and model-based spatiotemporal paleoclimatic reconstructions with paleoanthropological data compilations from Asia across time and space, we found, to our surprise, that H. sapiens dispersed to East Asia at the same time as the Asian summer monsoon was intensified. This suggests an important influence of the paleo-monsoon on the early dispersal of H. sapiens from Africa to East Asia," said Prof. AO, lead author of the study.

"In contrast to the strengthening of the Asian summer monsoon, the climate in much of southeast Africa worsened during the last interglacial. It is possible that these Asian and Southeast African hydroclimate changes acting together spurred the early dispersal of H. sapiens from Africa to East Asia," said Dr. Thibaut Caley, an author of the study and paleoclimatologist from Université de Bordeaux, France. In contrast, the lush vegetation in East Asia at the time would have attracted H. sapiens habitation.

To provide further quantitative evidence of climate effects on H. sapiens dispersal, Dr. RUAN Jiaoyang, corresponding author of the study and assistant researcher at the IBS Center for Climate Physics, South Korea, performed computer simulations of H. sapiens habitats and found that the H. sapiens occupation of East Asia was consistent with a transcontinental increase in simulated habitat suitability.

This study was funded by the Strategic Priority Research Program of CAS, the Second Tibetan Plateau Scientific Expedition and Research Program, and the National Natural Science Foundation of China.

JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2308994121

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Concurrent Asian monsoon strengthening and early modern human dispersal to East Asia during the last interglacial

ARTICLE PUBLICATION DATE

8-Jan-2024

Red deer populations in Europe: more influenced by humans than by wolves and other predators

Peer-Reviewed Publication

UNIVERSITY OF FREIBURG

Alongside the occasional bison and elk, red deer are Europe's largest native wild animal. An international study led by wildlife ecologists from the University of Freiburg has now investigated the factors that affect the red deer population in a particular area. The researchers were able to show that the population density of the animals in Europe is primarily influenced by human hunting and land use and not by large predators such as wolves, lynx and brown bears. “While large carnivores are often considered key factors in controlling prey populations in undisturbed ecosystems, this is less visible in human-dominated landscapes. Our study illustrates that these interactions are context-dependent,” says Dr. Suzanne T. S. van Beeck Calkoen, former PhD student at the Chair of Wildlife Ecology and Management at the University of Freiburg and first author of the study.

The researchers collected data on the population density of red deer at over 492 study sites in 28 European countries and analysed the influence of various factors such as habitat productivity, the presence of large carnivores, human activities, climatic variables and the protection status of the area. The evaluation of the data showed that human hunting reduced red deer density more than the presence of all large carnivores. Human land use, on the other hand, led to an increase in red deer density. In most cases, the presence of large carnivores had no statistically significant effect on the red deer population. Only when the three predators wolf, lynx and bear occurred together in one area did the number of red deer decrease. However, the study published in the Journal of Applied Ecology did not investigate how the presence of predators affects the behavior of red deer.

The return of the wolf
The study also sheds new light on the ongoing debate about the return of the wolf to Central Europe, notes Prof. Dr. Marco Heurich, Professor of Wildlife Ecology and Conservation Biology at the Faculty of Environment and Natural Resources at the University of Freiburg and initiator of the study. “Our research shows that the return of a large carnivore such as the wolf alone does not have a major impact on the occurrence of red deer. This is because in Central Europe, human influences predominate both indirectly through interventions in the red deer’s habitat and directly through the killing of the animals.” In addition, the mortality rate of wolves in Central European landscapes is very high, mainly due to road traffic, which further limits their influence on prey populations. “However, we also found a high variability in red deer densities, which indicates that there may be specific situations in which large carnivores do have an impact. Investigating this will be the task of future studies,” states Heurich.

Original publication: Suzanne T. S. van Beeck Calkoen, Dries P. J. Kuijper, Marco Apollonio, Lena Blondel, Carsten F. Dormann, Ilse Storch, Marco Heurich: “Numerical top-down effects on red deer (Cervus elaphus) are mainly shaped by humans rather than large carnivores across Europe.” In: Journal of Applied Ecology (2023). DOI: 10.1111/1365-2664.14526
Prof. Dr. Marco Heurich is Professor of Wildlife Ecology and Conservation Biology at the University of Freiburg
Dr. Suzanne T. S. van Beeck Calkoen completed her doctorate at the Chair of Wildlife Ecology and Management at the University of Freiburg. She is a research associate at the University of Göttingen and the Technical University of Dresden.

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JOURNAL

Journal of Applied Ecology

DOI

10.1111/1365-2664.14526