It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Monday, August 17, 2026
Ancient maritime voyagers carried symbolic art 4,000 years ago
A 4,000-year-old painted stone plaque discovered on a remote Indonesian island is the first known example of portable art belonging to the Austronesian Painting Tradition (APT), providing a rare glimpse into the symbolic world of some of history’s greatest maritime voyagers.
The discovery was made by an international team led by archaeologists from The Australian National University (ANU) and Indonesia’s National Research and Innovation Agency (BRIN) during excavations at Huknaur rockshelter on Wetar Island, eastern Indonesia.
The plaque bears a distinctive red concentric-circle and radiating “sun-ray” design characteristic of the APT – a style of rock art found across eastern Indonesia and the Western Pacific in regions where Austronesian languages are spoken.
Although APT paintings are widespread, most occur on cave and rockshelter walls and are difficult to date, leaving their chronology poorly understood. The Wetar plaque provides the first evidence that these designs were also painted on portable objects, while its securely dated archaeological context provides a rare age for this characteristic motif.
Lead author Professor Sue O’Connor, from The Australian National University (ANU), said the discovery changes our understanding of how these symbols may have been used.
"This is the first portable example of Austronesian painted art ever found archaeologically,” Professor O’Connor said.
“Portable symbols could travel with people and may have helped communicate shared identities, affiliations and beliefs between island communities. Similar sun-like designs were historically painted on boats and other objects, where they could function as symbols of protection and group identity.”
Co-author Dr Simona Kealy, of the ANU, said radiocarbon dating of the archaeological deposits placed the plaque between approximately 4,090 - 3,900 years ago, when Austronesian-speaking peoples were rapidly dispersing into Island Southeast Asia.
“This discovery shows that the characteristic sun-ray motif was already part of the APT during the earliest Austronesian expansion into southern Wallacea,” Dr Kealy said.
“These people were extraordinary seafarers, rapidly dispersing across thousands of kilometres of ocean. The Wetar plaque shows that art and shared symbolic traditions were part of this great maritime dispersal from its earliest phases.”
The plaque was found in a preceramic layer, indicating that the APT reached Wetar before pottery – one of the principal material traits traditionally used by archaeologists to trace Austronesian expansion.
ANU co-author Dr Ceri Shipton said this provides a new perspective on what the earliest Austronesian pioneers brought with them.
“This discovery shows that Austronesian pioneers arrived with a compelling ideology represented by the APT paintings, prior to more extended contacts bringing pottery,” Dr Shipton said.
“People didn’t just carry technologies and possessions when they voyaged to new islands. They carried ideas, identities, and new ways of understanding the world.”
The study, 4,000-year-old painted plaque from Southeast Indonesia reveals Austronesian Painting Tradition preceded Neolithic pottery, will be published in the Proceedings of the National Academy of Sciences (PNAS).
Credit: Credit: Robin Moore / Cary Institute of Ecosystem Studies
Tick-borne diseases are on the rise in the United States. Lyme disease is the most commonly reported, with nearly half a million people diagnosed each year. Caused by the bacterium Borrelia burgdorferi, it is most often spread by bites from blacklegged ticks. Lyme can be treated with antibiotics, but if untreated, infection can spread to the joints, heart, and nervous system, and some people can experience persistent symptoms.
For more than 35 years, researchers at the Cary Institute of Ecosystem Studies in Millbrook, New York have been studying how interactions between acorns, rodents, ticks, predators, and climate shape Lyme-disease risk in people. A new paper, published in Proceedings of the National Academy of Sciences, details nine of the research project’s most surprising findings to date. Several are outlined below.
“On balance, these surprises have enriched our knowledge of this system, helping us to inform management of tick-borne disease risk,” said lead author Richard Ostfeld, a Cary Institute disease ecologist who co-directs the research program with Shannon LaDeau. Ostfeld added that many of the findings would not have been possible without the decades of data the project has collected so far, which helps the team to statistically distinguish real trends and drivers from random events and correlations.
“Studies of this depth and length are incredibly rare,” said LaDeau. “This research has followed an ecological community — including oak trees, mammals, and microorganisms — examining how interactions like predation, parasitism, and competition shape the system over time. The evolution of understanding summarized in this paper is something you simply cannot get without such a long-term and system-focused study.”
White-tailed deer are less important than previously thought
When Lyme disease was first recognized in the United States in the 1980s, some researchers assumed white-tailed deer played an important role in spreading the disease, because deer killed by hunters in the fall often carry large numbers of adult ticks. Although deer do not infect ticks with the Borrelia pathogen, the logic was that more abundant deer might feed more adult female ticks, which would then be able to lay more eggs and produce more immature ticks.
However, after several decades of intensive research, the long-term study on the Cary Institute’s campus — a forested ecosystem spanning 2,000 acres in New York's Dutchess County — has not found a statistical relationship between deer abundance and the density of nymphal ticks, the life stage of ticks that is most likely to spread Lyme disease to people.
“We had detected a weak positive relationship between deer and subsequent nymph abundance over short subsets of the data,” said Ostfeld, “but the whole data set in its entirety shows no such thing.”
Mice matter more
While deer abundance wasn't associated with the number of nymphal ticks, mouse abundance was. The long-term study has shown that a strong mouse year boosted the next year’s number of nymphs by about 40%. White-footed mice are a high-quality food source for blacklegged tick larvae, and also happen to be very good at passing Borrelia burgdorferi bacteria to them.
Ticks that acquire Borrelia as larvae can transmit the bacteria when they feed as nymphs. This is the life stage that is most likely to infect people.
The acorn effect
The project has revealed that acorn masting — when a large number of oak trees drop their acorns at the same time — creates a food bonanza for mice, boosting their populations the following year, and nymphal ticks the year after that. Thus, a large acorn crop reliably predicts higher numbers of nymphal ticks two years later.
Mouse numbers don’t predict the proportion of Lyme-infected ticks
The researchers expected that, just as a large mouse population boosts the number of nymphal ticks, it would also boost the percentage of nymphal ticks that are infected, since mice are so good at transmitting B. burgdorferi. And in the early days of the monitoring program, the scientists observed this trend. But as the years wore on, the relationship disappeared.
“It kept me up at night,” said Ostfeld, “because it meant that my understanding of how the system works was incomplete or wrong.”
Eventually, the data suggested an explanation. Even though mice might be more abundant in some years, other hosts — such as skunks, squirrels, and opossums — might be more abundant as well. Most of those hosts are not very good at spreading B. burgdorferi to ticks, and thus reduce the prevalence of Lyme bacteria in nymphal ticks.
“So the infection prevalence in the nymphs really depends on how all the larval tick meals are distributed across all the hosts,” explained Ostfeld. “It would have been convenient if one host predicted that for us, but that has not been the case.”
Extreme temperatures don’t kill ticks in the wild
Lab work had previously suggested that blacklegged ticks are killed by extreme heat and extreme cold events, but Cary’s field studies found that in natural environments, the ticks beat the heat and cold presumably by sheltering deeper into soil and leaf litter. The team has, however, found a trend: years that are warmer overall predict lower-than-normal numbers of nymphal ticks. In contrast, warmer years are good for mouse populations, so this mix of effects will be important to continue monitoring.
Continuing the legacy
The big takeaways from the long-term monitoring program are that the ecological dynamics governing Lyme disease risk are complex but predictable. Knowing that mouse abundance, but not deer abundance, is linked to higher numbers of nymphal ticks — and that severe winter weather may not substantially reduce tick populations — can help public-health officials anticipate periods of elevated Lyme disease risk and guide prevention efforts.
There is still much to learn about ticks and the ecological variables that impact their chances of spreading diseases to people. In particular, one big research frontier will be sorting out how climate change is influencing ticks, their hosts, and oak trees.
“You would expect that a warming climate, which makes life better for the mice, would eventually make life better for the ticks, but we have not seen that so far,” said Ostfeld. “We need to know what to expect from the different manifestations of climate change, which are sometimes warmer and drier, and sometimes warmer and wetter. The time of year when it’s very warm also matters to ticks, oaks, and acorn production.”
Since the project began in 1991, the Dutchess County, New York study site has experienced climate change, landscape change, invasive species, and more. The authors plan to continue studying how ticks and their hosts respond to these evolving conditions, and how human health may be affected in the future.
U.S. National Science Foundation grant number DEB 24-32607 and DEB 25-38314.
Cary Institute of Ecosystem Studies is an independent nonprofit center for environmental research. Since 1983, our scientists have been investigating the complex interactions that govern the natural world and the impacts of climate change on these systems. Our findings lead to more effective resource management, policy actions, and environmental literacy. Staff are global experts in the ecology of: forests, soils, freshwater, disease, and cities.
The number of white-footed mice can help to predict the abundance of nymphal ticks, which are the life stage most likely to spread Lyme disease to people.
Credit
Credit: Robin Moore / Cary Institute of Ecosystem Studies
COLUMBUS, Ohio – New research suggests that no matter what we eventually determine the last common ancestor of humans and chimpanzees to be, we’ll learn it was a primate that climbed trees.
Humans and chimpanzees began their separate evolutionary paths between 6 and 7 million years ago when they split from the last common ancestor (LCA) they shared. Debate about the LCA hinges in part on the tree-dwelling environment from which humans emerged – which involved living among the high-up horizontal branches or being able to get there from the ground, or, more likely, both.
Chimpanzees have ankle flexion that makes them skilled tree trunk climbers, but monkeys have been thought to navigate trees with their arms – which would influence what kind of ancestor we’re looking for, one that climbed up trunks or lived in treetops full time.
Video evidence from West Africa suggests there may be no such distinction, at least based on foot structure: Researchers from The Ohio State University observed and confirmed with measurements that wild sooty mangabey monkeys, known to have feet that lack chimps’ versatile ankles, display foot bone flexibility that facilitates vertical climbing up skinny tree trunks to hide, forage or sleep.
“People are making behavioral inferences from fossils, and some say a monkey can’t vertically climb as well as an ape can,” said first study author Luke Fannin, assistant professor of anthropology at Ohio State. “We’re saying there’s a functional equivalence here. So you can’t rule out vertical climbing just because something doesn’t have a chimpanzee-like foot.”
Identifying the last common ancestor is considered key to helping us understand what led to bipedalism, which is done habitually only by humans. We know we’re apes, but this study makes the point that even if the ancestor had a more monkey-like foot morphology, it could still climb like an ape.
“Part of paleoanthropology is understanding how our evolution happened, and it’s often through the hallmark of how we move because modern humans move quite differently than our cousins, the chimpanzees, do, and they’re the living primate we’re most closely related to,” Fannin said. “And we’re trying to understand why that is.”
Fannin recorded the videos of mangabeys in the wild at the Taï Forest Monkey Project field station in Ivory Coast that is co-directed by W. Scott McGraw, professor and chair of anthropology at Ohio State and senior author of the paper.
“The great thing about having the video is that it allows us to capture exactly what the monkey is doing in a high-resolution manner. So we can actually say how the joint is loaded. Before, we had hunches, but in this way, it’s far more precise,” McGraw said.
The chimpanzee ankle can flex upward at a 45-degree angle during a tree climb, compared to most human ankles’ capacity to flex about 20 degrees. Fannin found that the mangabey foot achieves a 46-degree flex in its midfoot during a vertical climb.
This poses a challenge to differing schools of thought about how the LCA moved and the kind of foot it needed to get around a forest environment – theories differ on whether the foot structure was required to be more like a chimp’s or a monkey’s.
“What’s neat about this paper is it adds clarity, but it also makes the broader picture more fuzzy,” McGraw said. “Because this notion that you have to have a foot like an advanced ape to vertically climb, which is a difficult task, is not true. You’ve got a bunch of monkeys that aren’t extinct – and which can be filmed – that are very competent at performing a biomechanically challenging behavior right now in a forest in West Africa.
“The videos that Luke made in Taï are particularly important because they provide some of the first kinematic documentation of a locomotor behavior in a monkey that has largely been unrecognized or underappreciated.”
There are modern hunter-gatherers and human foragers who are competent vertical climbers as well, a skill believed to be associated with flexibility in their ligaments, tendons and muscles rather than their foot bones.
But Fannin and McGraw note that though modern humans may be defined by walking on two feet, we are focused on ascent, on reaching new heights in a literal sense – a sign that our arboreality, that ancestral connection to trees, is not just anatomical but also a behavioral hallmark.
“Arboreality is fundamental to understanding primates – including ourselves – because it has shaped our body to a large degree: hands and feet, wrists and ankles, nails instead of claws, etc.,” McGraw said.
Added Fannin, “Regardless of where you’re starting from, which we don’t know yet, vertical climbing is universal and the anatomy is going to perform that behavior. So I think that to get at the question of a monkey-like or ape-like last common ancestor, we need more fossils.”
This work was supported by Dartmouth College, the Explorer’s Club, the U.S. National Science Foundation, the Emory National Primate Research Center, the Primate Society of Great Britain and a Schmidt Sciences Postdoctoral Fellowship.
Former Ohio State undergraduate Carmen Pape was also a co-author.
BOZEMAN – A study led by a Montana State University research professor reveals how climate and hydrothermal activity have shaped the vegetation, wildfire and aquatic ecosystem history of the Yellowstone Plateau over the past 15,000 years.
Cathy Whitlock, MSU Regents Professor emerita of earth sciences in the College of Letters and Science and the first scientist to be elected to the National Academy of Sciences from a Montana university, has spent decades working in the Greater Yellowstone Ecosystem. Her interest in Yellowstone National Park’s Lower Geyser Basin was piqued in 2020 after she and co-author Chris Schiller took sediment cores from the bottom of one of the basin’s small lakes. They noticed that its contents differed from those in lakebeds in other parts of the park, suggesting that distinct geologic factors may have influenced the lake’s evolution. At about the same time, she read a paper speculating that a lack of water in the geyser system caused Old Faithful to stop erupting in the early 13th century for about 100 years.
As founder and past director of MSU’s 22-year-old Paleoecology Laboratory, which studies how past ecosystems responded to changing climates, Whitlock said the opportunity to learn more about Yellowstone’s geyser basins was irresistible. but also required the expertise of many scientific disciplines.
“I thought, ‘Well, there have been long, dry periods in Yellowstone in the past, some of them lasting for several centuries. I wonder if we could document how periods of sustained drought affected ancient geyser activity,’” she said.
Collaborators on the project included MSU professor of earth sciences Dave McWethy, two MSU post-doctoral researchers, two MSU students, and scientists from the U.S. Geological Survey, Oregon State University, Manchester University and Colorado State University.
Throughout her career, Whitlock has reconstructed the histories of ecosystems from tiny clues deposited over time in the layers of lake sediments. By examining sediment cores, scientists can pinpoint the age of the layers through radiocarbon dating or from the buried evidence of known, natural events, such as past volcanic eruptions. Pollen assemblages tell scientists what type of vegetation was present at particular times. Layers with abundant charcoal identify past wildfire events. The concentration of arsenic and cesium and the composition of the diatoms in the sediments provide information on changes in hydrothermal activity, lake chemistry and water depth.
In this study, the team collected core samples from small lakes of different ages in the Lower Geyser Basin, which is Yellowstone’s largest geyser system. The lakes are closed, meaning that they have no inflowing or outflowing streams. Whitlock said they likely developed in depressions left by hydrothermal explosions that occurred during wet climate periods. Two of the lakes, in fact, formed shortly after the glaciers that once covered the region melted; removal of ice released overlying pressure that probably led to lake-forming, hydrothermal eruptions.
Pollen records from the lakes indicate that after the ice receded, a grassy steppe ecosystem developed on the rhyolite volcanic soils. Steppe was replaced by a lodgepole pine forest that established between 12,800 and 11,000 years ago. Despite subsequent changes in climate, these pine forests have changed little in composition, leading the authors to suggest that lodgepole pine will continue to dominate the vegetation on the plateau even as the climate continues to warm in the future.
“The persistence of lodgepole pine for thousands of years is explained by the infertile soils on the rhyolite volcanic plateau and lodgepole’s adaptation to fire. It’s been very hard for anything else to get established in that area given limited nutrients and well-drained substrates,” Whitlock said. “While the vegetation has been remarkably insensitive to past climate change, fire activity on the plateau has responded dramatically.”
The team realized the importance of both geology and climate in explaining the environmental history of the geyser basin when the lake records were compared with high-resolution paleoclimate model results for Yellowstone. For example, the model showed that summers in the geyser basin were warmer and drier than today’s between 12,000 and 6,000 years ago, an observation that matched the charcoal evidence for more fires and the diatom records for lower lake levels then.
Whitlock said reconstructing a long-term fire history is extraordinarily complex, and the project wouldn’t have been possible without the baseline research her group conducted for 10 years after the Yellowstone fires of 1988.
“As soon as the fires were over, we started studying charcoal deposition into lakes to determine how far charcoal particles traveled during a fire, how long they took to get buried in the mud, that kind of thing,” she said. “The charcoal analytical techniques we developed for Yellowstone are now used in fire history studies on every continent. We have a much better understanding of fire as a global phenomenon because of the work we did following the 1988 fires.”
Sediments in the Lower Geyser Basin lakes reveal that Yellowstone’s hydrothermal systems were more active in the past during wet periods than dry ones, suggesting that future warming in Yellowstone may result in reduced hydrothermal activity, as well as increased wildfire incidence.
Research geophysicist Michael Poland, scientist-in-charge of the USGS Yellowstone Volcano Observatory, said such changes likely won’t be noticeable on the timescale of a human lifetime, though the study does point to interesting possibilities for near-term changes in the timing, force and frequency of geysers in Yellowstone’s hydrothermal areas.
“This study and ones like it help to give us a sense of what might be expected in the future for hydrothermal activity given current trends in climate,” he said. “That’s always been a key aspect of geology, and these sorts of studies show the past is the key to the present, which is then the key to the future. The more we understand past conditions and what drove them, the more we understand what’s likely to occur in the future.”
CORVALLIS, Ore. – A current system in the Atlantic Ocean that shapes regional climates and distributes ocean nutrients also serves as a control knob to help regulate temperatures across the planet, new research has found.
An analysis of past natural oscillations in the strength of the Atlantic Meridional Overturning Circulation system, or AMOC, shows that during periods with a strong AMOC, the global ocean and planet lost heat. When the AMOC was weak, the global ocean and planet gained additional heat.
“The AMOC works like a heat valve that controls the energy budget of the planet,” said Christo Buizert, a paleoclimatologist at Oregon State University and lead author of the study, which was just published in Nature Geoscience.
Researchers have long known that the AMOC plays an important role in the circulation of heat by global ocean currents. While the AMOC has been strong over the last 11,700 years, since the end of the last Ice Age, many climate models project future weakening of the AMOC due to human-driven climate change.
Such AMOC weakening would exacerbate warming across the planet, said Buizert, an associate professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences. The most direct impact of AMOC weakening is cooling in the North Atlantic and the regions surrounding it, including Greenland.
“However, when we zoom out and look at the entire planet, the total amount of heat actually increases,” Buizert said.
Previous research has shown that during each of the Earth’s Ice Ages, which happened repeatedly between 11,700 years ago and 2.7 million years ago, the AMOC underwent a series of abrupt changes, known as Dansgaard-Oeschger events. These abrupt changes are probably the best example of climate “tipping points” – the critical thresholds that, when crossed, lead to sudden and potentially irreversible climate change.
During weak AMOC periods, abrupt cooling in the North Atlantic plunged areas such as present-day Europe, Greenland and New York into much colder temperatures. The prevailing scientific theory suggested that heat was transferred to the southern hemisphere in a theory known as the “thermal bipolar seesaw.”
The new research shows that instead of a simple redistribution of heat, there is actually a net increase in the heat stored by the global ocean.
“To put this into perspective, events of AMOC weakening during the last Ice Age caused the same amount of warming as 25 ppm of carbon dioxide would today. That is the equivalent of about 10 years of human emissions.”
To reach these conclusions, the researchers created a new framework, using simulations of abrupt AMOC change from three different climate models. In these three models, they tracked how heat moves around in the oceans and how much was lost or gained by the planet as a whole.
The ocean is continually taking up heat from sunlight, mostly in the tropics. When the AMOC is strong, that heat is circulated by ocean currents to the North Atlantic, where it is lost to the atmosphere in a process called deep ocean convection.
The new study found that when the AMOC weakens, this heat instead builds up in the interior of the ocean, including the North Atlantic. Only a thin surface layer of the North Atlantic cools down, while the rest of the ocean warms up.
“It’s as if the whole ocean acts as a giant bucket of heat,” Buizert said. The AMOC acts as a spigot that controls how much of that heat can flow out.
There is a silver lining, though.
“Our research also shows that in a warmer world, the AMOC tends to be more stable, which would suggest that these ‘tipping point’ events might not occur in the future,” Buizert said. “There would be a future weakening of the AMOC with climate change, but it could recover. An irreversible collapse of the AMOC might not occur. But more research is needed to better understand the future stability of the AMOC.”
Studies of the naturally occurring past changes to the AMOC are not a perfect comparison for modern-day climate shifts, but the more researchers can learn about the past, the better it helps understand what the future could look like, Buizert said.
Additional research is needed to further understand the role a changing AMOC plays in weather and climate patterns around the globe.
Coauthors of the study were: Ayako Abe-Ouchi, Yuta Kuniyoshiand Sune Olander Rasmussenof the University of Tokyo; Guido Vettorettiof the University of Copenhagen; Xu Zhangof the British Antarctic Survey and Xi’an Jiaotong University of China; Sarah Shackletonof Woods Hole Oceanographic Institution; Joel B. Pedro of the Australian Antarctic Division and the University of Tasmania; Eric D. Galbraith of the Universitat Autonoma de Barcelona and McGill University; and Thomas F. Stockerof the University of Bern, Switzerland.
