A University of Hawaiʻi researcher says he may have found a new human species called Homo juluensis, which includes mysterious groups like the Denisovans—ancient human relatives whose histories are still being uncovered.
Professor Christopher J. Bae from the University of Hawaiʻi at Mānoa's Department of Anthropology in the College of Social Sciences has been studying human ancestors across Asia for more than 30 years. His recent research, published in Nature Communications, helps clear up some of the confusion about the different types of ancient human-like species that co-existed in the region during the late Middle and early Late Pleistocene, a period roughly 300,000 to 50,000 years ago.
Homo juluensis lived approximately 300,000 years ago in eastern Asia, hunted wild horses in small groups, and made stone tools and possibly processed animal hides for survival before disappearing around 50,000 years ago.
It was proposed that the new species include the enigmatic Denisovans, a population known primarily through DNA evidence from a few physical remains found in Siberia, and a few fossils found in Tibet and Laos. More research is clearly needed to test this relationship, which is primarily based on similarities between jaw and teeth fossils from these different sites.
Organization breakthrough
Bae credits a new way of organizing fossil evidence for the breakthrough. Some may think of it as organizing an old family photo album where some pictures are blurry or hard to identify. Bae and his research team have essentially created a clearer system for sorting and understanding these ancient human fossils from China, Korea, Japan and southeast Asia.
"This study clarifies a hominin fossil record that has tended to include anything that cannot easily be assigned to Homo erectus, Homo neanderthalensis or Homo sapiens," Bae said. "Although we started this project several years ago, we did not expect to be able to propose a new hominin (human ancestor) species and then to be able to organize the hominin fossils from Asia into different groups. Ultimately, this should help with science communication."
This work is important because it helps scientists—and the rest of us—better understand the complex story of human evolution in Asia, filling in some of the gaps in our understanding of our ancient relatives.
Bae's co-author is Xiujie Wu, a senior professor from the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, in Beijing, China, and lead author on the taxonomic assignment and description of Homo juluensis.
Aging is a complex process involving genetic changes and physiological shifts, with the gut microbiome emerging as a critical yet understudied factor influencing health. New research explores the evolving gut microbiome’s role in aging, its impact on immunity, metabolism, and diseases, and highlights interventions like probiotics and diet to promote healthy aging.
The gut microbiome profoundly influences aging, and its modulation may support healthy aging and disease prevention.
Aging is a universal and intricate process impacting all living organisms, marked by key genetic features like telomere shortening, genomic instability, and epigenetic alterations. As time progresses, aging induces physical, biochemical, and metabolic changes within the human body.
One significant yet understudied factor in this process is the gut microbiome (GM)—a diverse microbial community that profoundly influences health. This review delves into the dynamic interplay between the gut microbiome and aging, highlighting microbiota-dependent mechanisms that regulate aging, and examines interventions aimed at promoting healthy aging through microbiome modulation.
Dynamics of Gut Microbiome Across Lifespan
From birth, the gut microbiome evolves, influenced by childbirth mode, breastfeeding, and early-life exposure to microbes. In infancy, the microbiome is less diverse, dominated by Bifidobacterium in breastfed babies and Bacteroides in formula-fed infants.
The composition of the gut microbiome exhibits genus-level variations across different age groups. The early-age gut microbiome is shaped by the embryonic environment, type of delivery, and exposure to microbes through breast/formula feeding. During weaning, the microbiome undergoes changes from a simple (less diverse) to a complex (more diverse) microbial mixture and attains stability until adulthood.
During puberty, the microbiota differentiates based on the sex of the host due to associated hormonal changes.
In elderly individuals, the microbiota is affected by lifestyle, dietary habits, and immunosenescence of the intestinal immune system. In this age group, the microbiome is mainly dominated by pathogenic and opportunistic microbes.
The major changes in the metabolites associated with human GM and the length of the intestine concerning the aging process are also shown.
Created by biorander.com. GM, gut microbiota; HMOs, human milk oligosaccharides; IgA, immunoglobulin A; SCFA, short-chain fatty acids; TGF-β, transforming growth factor-β.
Credit: Tulika Prakash
By adulthood, a robust “core microbiome” develops, modulating immune and metabolic functions. Puberty introduces sex-related changes in the microbiome, primarily due to hormonal influences. In older adults, microbial diversity decreases, leading to an abundance of frailty-linked microbes like Christensenellaceae and reduced SCFA producers. These changes impact age-related conditions such as sarcopenia and osteoporosis.
Gut Microbiome and Aging-Related Disorders
Aging-associated shifts in the gut microbiome are linked to various age-related diseases, including neurodegenerative disorders like Alzheimer’s disease (AD) and Parkinson’s disease (PD). Dysbiosis, or microbial imbalance, has been implicated in inflammaging, a chronic, low-grade inflammation that accelerates aging.
This process is tied to diseases such as AD, PD, cardiovascular conditions, and Type 2 diabetes. Reduced levels of beneficial SCFA-producing bacteria and increased gut permeability exacerbate inflammation, which accelerates disease progression.
Gut Microbiome and Immune System
The gut microbiome plays a crucial role in shaping the immune system, from infancy to old age. Immunosenescence, a gradual decline in immune function, is closely tied to changes in the gut microbiome. Loss of gut microbial diversity diminishes the immune system’s ability to fend off infections, which is particularly problematic in the elderly.
Studies show that maintaining microbial balance in older adults can potentially delay immunosenescence and improve immune response, reducing susceptibility to infections and age-related diseases.
Metabolic Changes and Gut Microbiome
The gut microbiome produces a range of metabolites, including SCFAs, polyamines, and reactive oxygen species (ROS), that influence metabolic processes and aging.
SCFAs like butyrate have been shown to prevent age-related physiological decline by enhancing intestinal barrier function, modulating immune responses, and inhibiting cellular senescence. However, dysbiosis disrupts these processes, contributing to metabolic disorders such as obesity and insulin resistance.
Interventions for Healthy Aging
Microbiome modulation through prebiotics, probiotics, and dietary interventions shows promise in promoting healthy aging. Probiotic strains such as Bifidobacterium longum and Lactobacillus rhamnosus have been linked to enhanced immune function and reduced inflammation in older adults.
Physical activity and a balanced diet also help maintain a diverse and stable microbiome, which is crucial for longevity and health in aging populations.
Conclusions
The gut microbiome holds a central role in human aging, influencing everything from metabolic function to immune health. By modulating the gut microbiome through lifestyle changes and interventions, it may be possible to slow down the aging process, reduce the risk of age-related diseases, and promote healthier aging.
Men commit suicide much more often than women. Those who want to live up to the traditional male image of strength and independence are particularly at risk. Prevention measures should focus more on them in future, according to a new study published in Heliyon.
The global suicide rate among men is between two and four times that of women, including in Switzerland. One reason for this considerable difference is that the risk in men is often recognized too late. However, not all men are equally at risk.
A project by a research group from the Department of Psychology at the University of Zurich has now identified socio-cultural factors that significantly raise the risk of suicide among men. "We should consider targeted preventive measures for this sub-group," says team leader Andreas Walther.
A long-term study in the U.S. involving about 10,000 young men has already shown that they are more likely to commit suicide over a period of 20 years if they identify strongly with traditional masculine roles.
These norms are characterized by ideas that originated from a previously strongly patriarchal social framework. They prescribe the characteristics that men should have and how they should behave. These include, for example, independence, controlling their emotions and not showing their vulnerability. In science, this is summarized under the term "traditional masculine ideologies."
"In our study, we wanted to take a much closer look at which aspects of these ideologies play a role in the suicide risk," explains Walther. To do so, the team recruited almost 500 men from German-speaking countries using flyers and calls put out on social media. The study participants completed a range of questionnaires that, among other things, assessed symptoms of depression, conformity with traditional masculine ideologies and suicidal thoughts and behavior.
Combination of characteristics and attitudes results in tunnel vision
This showed that 13% of the participants had already attempted suicide, a quarter reported having been diagnosed with depression and a fifth had already had psychotherapy. First author Lukas Eggenberger points out that these high proportions may not be representative. "A study call of this kind tends to appeal to people who already experience mental health problems."
However, this had no effect on the evaluation of the data with regard to socio-cultural factors. Men whose responses indicated a high potential risk were made aware of the help available to them.
"The analysis of the survey showed that it is possible to distinguish between three groups," says Eggenberger.
For about 60% of the participants, conformity with traditional masculine ideologies did not play a major role. The researchers described this group as Egalitarians.
About 15%—whom they called Players—have an image of masculinity that primarily manifests in a patriarchal attitude. It is also important to these men to have many female sexual partners and be perceived as heterosexual.
The last group, named Stoics by the researchers, comprises about a quarter of the men. They strongly conform with the traditional norms—although not primarily with regard to status and sexual success like the Players, but to factors such as controlling their emotions, inde-pendence and risk-taking, for example, driving fast or doing extreme sports.
The evaluation of the questionnaires with regard to suicide risk showed that the Stoics were at more than double the risk of suicide attempts compared with the Egalitarians. In contrast, the risk was not significantly increased for the Players. "Especially in stressful situations or a mental health crisis, the Stoics' attitudes pose a highly problematic combination," says Eggenberger.
"They would think something like: 'I can't show my feelings, and I have to solve my problems myself.' Coupled with the high willingness to take risks typical of the Stoics, this can produce a kind of tunnel vision—and suicide sometimes seems the only possible way out.
The study also shows that traditional attitudes are in no way reserved solely for the older generation—quite the opposite: The Stoics group was considerably younger than the other groups. Eggenberger has an idea of why this might be: "From a developmental theory perspective, young adulthood is a key phase in the search for identity. Traditional masculine ideologies offer young men a means to define themselves in terms of their gender, to belong to a club of men, so to speak."
Better recognition of depression for prevention
On the basis of the research findings, the study team recommends the development of interventions that are specifically tailored to the Stoics. For example, medical professionals could be made more aware of these men. A retrospective study of almost 3,000 suicides in Canada showed that 60% of the men concerned had sought help from mental health specialists in the previous year.
"However, they may not have been properly understood and ended up falling through the cracks," says Walther. He also suggests one possible reason: "In these men, depression often does not take the form of classic symptoms, but of somatic problems such as back pain. They also often express their negative feelings through aggression or risky behavior rather than talking about them." This has been documented in numerous studies carried out by different research groups.
Untreated depression has been proven to play a key role in the increased suicide rate among men. As part of the project, the team is therefore also developing and validating a male-specific psychotherapy for depression. "Among other things, this is based on reducing their conformity with traditional gender roles."
Paul Watson, the iconic environmental activist and founder of the organization Sea Shepherd, is no stranger to clashes with corporations and governments. Known for his bold and often controversial actions, he has dedicated his life to protecting marine wildlife, with Japanese whaling being one of his primary targets. Now, Watson faces a new legal battle: imprisoned in Greenland, he risks extradition to Japan. Japanese authorities accuse him of "conspiracy to board" their whaling vessel Shonan Maru 2 during two incidents in Antarctic waters in February 2010. One of his tactics involved deploying butyric acid stink bombs—symbolic but harmless acts intended to disrupt operations by emitting an unbearable stench.
In Japan, Watson's actions are often seen as a provocative assault on a cultural tradition, a perspective highlighted by some European media outlets. However, this narrative overlooks the powerful industrial machinery behind Japanese whaling. While tradition plays a role, Japan's whaling operations are also driven by a government-supported industrial complex. Watson's current battle is not merely against what some view as a "barbaric" cultural practice but against a highly organized and politically protected system that has persisted for decades. To fully grasp what's at stake for Watson, it's essential to understand this industrial context.
The cultural and economic roots of Japanese whaling
Japan's whaling tradition dates back centuries, originating in coastal communities that relied on whales for food and materials. However, these early practices were small-scale, vastly different from the industrialized operations Watson critiques today. In 2023 alone, Japan's whaling fleet killed nearly 300 whales, with authorities setting a 2024 target of 200.
The notion of whaling as a cultural tradition took on new symbolism after World War II, when the Japanese government promoted whale meat consumption to address severe food shortages. It became a staple in school lunches, embedding itself in the national identity as a symbol of resilience during times of hardship.
A declining demand
Despite its historical roots, whale meat has lost its place in modern Japanese diets, particularly among younger generations. In 2023, consumption fell to just 2,000 tons, a stark contrast to the 200,000 tons consumed annually in the 1960s. Uses for whale byproducts, such as oil for candles or cosmetics, have also dwindled with the advent of petroleum substitutes.
Nevertheless, Japan's government continues to defend whaling as an inalienable sovereign right, framing it as a cultural issue in defiance of the 1986 international moratorium on commercial whaling. This pits Japan's claims of cultural preservation against global calls to ban whaling as incompatible with contemporary values.
Defenses of whaling as an expression of "cultural authenticity"—and not as a response to a domestic market that has all but collapsed—appear to be driven by powerful industrial and financial interests, weakening the cultural justification. Furthermore, the relentless industrialization of Japan's whaling practices has rendered comparisons to traditional methods obsolete. Unlike the small-scale, limited-impact techniques of the past, today's operations occur on a vastly larger scale with far greater consequences for whale populations.
This shift fuels the debate between environmentalists and whaling proponents, raising questions about sustainability and the true motivations behind Japan's insistence on maintaining the practice.
Targeting the 'floating factories'
Japan's whaling fleet is equipped with highly specialized vessels, some of which function as true "floating factories," capable of capturing, processing and packaging whales directly at sea. This allows Japan to discreetly circumvent international regulations, because the whales are integrated into the supply chain before reaching land. Once ashore, whale meat is distributed through a network that extends to markets and restaurants across the country, including high-end establishments, thereby reinforcing the social acceptance of whaling. The government's significant financial support for the whaling industry highlights the strong political and economic interests behind the practice.
It is true that "floating factories" are not a modern invention; they date back to the 19th century, when ships were equipped to process whale oil at sea. These vessels allowed whalers to immediately handle their catch, avoiding long and costly trips back to shore. Fitted with boilers and advanced cutting mechanisms for their time, these early floating factories made whale exploitation more efficient. A reading of Moby-Dick by Herman Melville vividly illustrates this reality. Today, Japan's whaling practices undeniably continue this tradition, but with a dramatic shift in scale, driven by aggressive industrial and logistical optimization.
For Watson and Sea Shepherd, confronting Japanese whaling is a daunting challenge. Operating as a nonprofit, Sea Shepherd lacks the financial and logistical resources of Japan's state-backed whaling fleet. Instead, Watson has turned to direct-action campaigns, deploying aggressive tactics such as blocking harpoons, positioning ships between whalers and their prey and occasionally ramming whaling vessels. These actions aim to disrupt the industrial supply chain, delaying or halting operations without causing harm to human life.
Watson's approach highlights the broader societal debate over the global responsibility to protect biodiversity and the limits of cultural relativism. While his actions have sparked controversy, they have also drawn attention to the vast industrial machinery sustaining Japan's whaling operations.
The bigger picture
Watson's fight transcends the immediate goal of disrupting whaling operations. It represents a clash between environmental preservation and deeply entrenched practices often defended on cultural grounds. Japan's whaling industry, supported by powerful lobbying and government intervention, poses a formidable challenge to environmental activism.
As Watson remains imprisoned and faces potential extradition, the debate over his actions—and the future of Japan's whaling practices—continues to unfold. Behind the cultural rhetoric lies a stark reality: industrial whaling is driven by economic and political interests that overshadow its purported traditional roots. The question remains whether such a system, so deeply embedded, can ever be fundamentally challenged.
Human footprints stir the imagination. They invite you to follow, to guess what someone was doing and where they were going. Fossilized footprints preserved in rock do the same—they record instances in the lives of many different extinct organisms, back to the earliest creatures that walked on four feet, 380 million years ago.
Discoveries in eastern Africa of tracks made by hominins—our ancient relatives—are telling paleontologistslikeourselves about the behavior of hominin species that walked on two feet and resembled us but were not yet human like we are today. Our new research focuses on footprints that amazingly record two different species of hominins walking along the same Kenyan lakeshore at the same time, roughly 1.5 million years ago.
Studying ancient tracks like these fills in exciting pieces of the human evolution story because they provide evidence for hominin behavior and locomotion that scientists cannot learn from fossilized bones.
Finding first fossilized footprints in Kenya
The first discovery of tracks of early hominins in Kenya's Lake Turkana region happened by chance in 1978. A team led by one of us (Behrensmeyer) and paleoecologist Léo Laporte was exploring the geology and fossils of the rich paleontological record of East Turkana. We focused on documenting the animals and environments represented in one "time slice" of widespread sediments deposited about 1.5 million years ago.
We collected fossils from the surface and dug geological step trenches to document the sediment layers that preserved the fossils. The back wall of one of the trenches showed deep depressions in a layer of solidified mud that we thought might be hippo tracks. We were curious about what they looked like from the top down—what scientists call the "plan view"—so we decided to expose 1 square meter of the footprint surface next to the trench.
When I returned from more fossil bone surveys, Kimolo Mulwa, one of the expert Kenyan field assistants on the project, had carefully excavated the top of the mudstone layer and there was a broad smile on his face. He said, "Mutu!"—meaning "person"—and pointed to a shallow humanlike print in among the deep hippo tracks.
I could hardly believe it, but, yes, a humanlike footprint was clearly recognizable on the excavated surface. And there were more hominin tracks, coming our way out of the strata. It was awe-inspiring to realize we were connecting with a moment in the life of a hominin that walked here 1½ million years ago.
We excavated more of the surface and eventually found seven footprints in a line, showing that the hominin had walked eastward out of softer mud onto a harder, likely shallower surface. At one point the individual's left foot had slipped into a deep hippo print and the hominin caught itself on its right foot to avoid falling—we could see this clearly along the trackway.
Even today on the shore of modern Lake Turkana, it's easy to slip into hippo prints, especially if the water is a bit cloudy. We joked about being sorry our hominin track-maker didn't fall on its hands, or face, so we could have a record of those parts, too.
Another set of tracks
Over four decades later, in 2021, paleontologist Louise Leakey and her Kenyan research team were excavating hominin fossils discovered in the same area when team member Richard Loki uncovered a portion of another hominin trackway. Leakey invited one of us (Hatala) and paleoanthropologist Neil Roach to excavate and study the new trackway, because of our experience working onother homininfootprint sites.
The team, including 10 expert Kenyan field researchers led by Cyprian Nyete, excavated the surface and documented the tracks with photogrammetry—a method for 3D imaging. This is the best way to collect track surfaces because the sediments are not hard enough—what geologists call lithified—to remove from the ground safely and take to a museum.
The newly discovered tracks were made approximately 1.5 million years ago. They occur at an earlier stratigraphic level than the ones we found in 1978 and are about a hundred thousand years older, based on dating of volcanic deposits in the East Turkana strata.
Who was passing through?
These footprints are especially exciting because careful anatomical and functional analysis of their shapes shows that two different kinds of hominins made tracks on the same lakeshore, within hours to a few days of each other, possibly even within minutes!
We know the footprints were made very close together in time because experiments on the modern shoreline of Lake Turkana show that a muddy surface suitable for preserving clear tracks doesn't last long before being destroyed by waves or cracked by exposure to the sun.
This is the first time ever that scientists have been able to say that Homo erectus and Paranthropus boisei—one our likely ancestor and the other a more distant relative—actually coexisted at the same time and place. Along with many different species of mammals, they were both members of the ancient community that inhabited the Turkana Basin.
Not only that, but with the new tracks as references, our analyses suggest that other previously describedhominin tracksin the same region indicate that these two hominins coexisted in this area of the Turkana Basin for at least 200,000 years, repeatedly leaving their footprints in the shallow lake margin habitat.
Other animals left tracks there as well—giant storks, smaller birds such as pelicans, antelope and zebra, hippos and elephants—but hominin tracks are surprisingly common for a land-based species. What were they doing, returning again and again to this habitat, when other primates, such as baboons, apparently did not visit the lakeshore and leave tracks there?
These footprints provoke new thoughts and questions about our early relatives. Were they eating plants that grew on the lakeshore? Some paleontologists have proposed this possibility for the robust Paranthropus boisei because the chemistry of its teeth indicates a specific herbivorous diet of grasslike and reedlike plants. The same chemical tests on teeth of Homo erectus—the ancestral species to Homo sapiens—show a mixed diet that likely included animal protein as well as plants.
The lake margin habitat offered food in the form of reeds, freshwater bivalves, fish, birds and reptiles such as turtles and crocodiles, though it could have been dangerous for bipedal primates 4 or 5 feet (1.2 to 1.5 meters) tall. Even today, people living along the shore occasionally are attacked by crocodiles, and local hippos can be aggressive as well. So, whatever drew the hominins to the lakeshore must have been worth some risk.
For now it's impossible to know exactly how the two species interacted. New clues about their behavior could be revealed with future excavations of more trackway surfaces. But it is fascinating to imagine these two hominin "cousins" being close neighbors for hundreds of thousands of years.
Ancient footprints you can visit
Earlier excavations of hominin trackways near a village called Ileret, 25 miles (40 km) to the north of our new site, are being developed as a museum through a project by the National Museums of Kenya. The public, the local Daasanach people, educational groups and tourists will be able to see a large number of 1.5-million-year-old hominin footprints on one excavated surface.
That layer preserves tracks of at least eight hominin individuals, and we now believe they represent members of both Homo erectus and Paranthropus boisei. Among these is a subset of individuals, all about the same adult size, who were moving in the same direction and appear to have been traveling as a group along the lake margin.
The museum built over the track site is designed to prevent erosion of the site and to protect it from seasonal rains. A community outreach and education center associated with the museum aims to engage local educational groups and young people in learning and teaching others about this exceptional record of human prehistory preserved in their backyard. The new site museum is scheduled to open in January 2025.
In his taxonomy of consciousness, Robert Lawrence Kuhn categorizes theories from materialist to nonmaterialist, exploring their implications for AI, immortality, and free will. His findings, based on interviews with numerous experts, are detailed in a 2024 journal article.
Kuhn’s taxonomy of consciousness connects various theories to deep questions about human existence and AI, based on his extensive dialogue with over 200 experts.
“Out of meat, how do you get thought? That’s the grandest question,” said philosopher Patricia Churchland to Robert Lawrence Kuhn, the producer and host of the acclaimed PBS program Closer to Truth and member of FQxI’s scientific advisory council.
Kuhn has now published a comprehensive taxonomy of proposed solutions and theories regarding the hard problem of consciousness. His organizing framework aims to assess their impact on meaning, purpose, and value, as well as on AI consciousness, virtual immortality, survival beyond death, and free will. His work, titled ‘Landscape of Consciousness,’ appeared in the August 2024 issue of the journal Progress in Biophysics and Molecular Biology.
FQxI President Anthony Aguirre (left) and Closer To Truth’s Robert Lawrence Kuhn (right) discuss consciousness at FQxI’s 5th International Conference in Banff, Canada.
Since its debut in 2000, Closer To Truth has broadcast 333 episodes, including 30 in collaboration with Foundational Questions Institute, FQxI, a science think tank and funding agency. Kuhn’s article is the culmination of numerous in-depth interviews with experts over the decades.“I have discussed consciousness with over 200 scientists and philosophers,” says Kuhn, who is himself trained in neurophysiology. “Landscape is the product of a lifetime.”
Theories and Frameworks
The article begins with the classic mind-body problem: How do the felt experiences in our minds relate to the neural processes in our brains? How do mental states, whether sensory, cognitive, emotional, or even noumenal (self-less) awareness, correlate with brain states? “Although there are families of mind-body problems, I focus tightly on phenomenal consciousness: our inner awareness, ‘what it feels like to be’ something,” says Kuhn.
FQxI and Closer To Truth’s Robert Lawrence Kuhn (middle) interviews cosmologists Alan Guth (left) and Andrei Linde (right) during an FQxI meeting.
Kuhn presents diverse theories of consciousness, from materialist/physicalist to nonmaterialist/nonphysicalist. These are categorized as Materialism Theories (philosophical, neurobiological, electromagnetic field, computational and informational, homeostatic and affective, embodied and enactive, relational, representational, language, phylogenetic evolution); Non-Reductive Physicalism; Quantum Theories; Integrated Information Theory; Panpsychisms; Monisms; Dualisms; Idealisms; Anomalous and Altered States Theories; and Challenge Theories. “Each explanation is self-described by its adherents,” notes Kuhn.
The taxonomy is laid out in the accompanying figure.
Created by Robert Lawrence Kuhn and Alex Gomez-Marin
Methodology and Purpose
“My purpose must be humble: collect and categorize, not assess and adjudicate,” says Kuhn. “Seek insights, not answers.” Kuhn produced the organizing framework for these diverse theories of consciousness in order to explore their impact on “ultimate questions,” such as meaning, purpose, and value (if any), AI consciousness, virtual immortality, survival beyond death, and free will, he says. “Understanding consciousness at this point cannot be limited to selected ways of thinking or knowing, but should seek expansive yet rational diversity.”
Reflections on Theories of Consciousness
Having produced an article of around 175,000 words, Kuhn found that his opinions on certain proposals had evolved. “My own hunch, right here, right now might be something of a Dualism-Idealism mashup. Second place might go to some form of Quantum Consciousness, triggered by writing this paper and surprising me. Third place, counterintuitively, to a kind of Eliminative Materialism/Illusionism, combined with Neurobiological and Representational Theories.”
But, adds Kuhn, “Smart, serious folks believe radically different theories; what I believe doesn’t much matter.”
Scientists have managed to quantify methanethiol emissions in the oceans on a global scale for the first time.
Credit: Rafel Simó (ICM-CSIC)
For the first time, researchers have quantified the global emissions of a sulfur gas produced by marine life, revealing that it cools the climate more than previously thought, especially over the Southern Ocean.
The study, published in the journal Science Advances, shows that the oceans not only capture and redistribute the sun's heat, but produce gases that make particles with immediate climatic effects; for example, through the brightening of clouds that reflect this heat.
This broadens the climatic impact of marine sulfur because it adds a new compound, methanethiol, that had previously gone unnoticed. Researchers only detected the gas recently, because it had previously been notoriously hard to measure. Earlier work had focused on warmer oceans, whereas the polar oceans are the emission hotspots.
The research was led by a team of scientists from the Institute of Marine Sciences (ICM-CSIC) and the Blas Cabrera Institute of Physical Chemistry (IQF-CSIC) in Spain. They included Dr. Charel Wohl, previously at ICM-CSIC and now at the University of East Anglia (UEA) in the UK.
Their findings represent a major advance on one of the most groundbreaking theories proposed 40 years ago about the role of the ocean in regulating Earth's climate.
This suggests that microscopic plankton living on the surface of the seas produce sulfur in the form of a gas, dimethyl sulfide, that—once in the atmosphere—oxidizes and forms small particles called aerosols.
Aerosols reflect part of the solar radiation back into space and therefore reduce the heat retained by the Earth. Their cooling effect is magnified when they become involved in making clouds, with an effect opposite of—but of the same magnitude as—that of well-known warming greenhouse gases such as carbon dioxide or methane.
The researchers argue that this new work improves our understanding of how the climate of the planet is regulated by adding a previously overlooked component, and that the work illustrates the crucial importance of sulfur aerosols. They also highlight the magnitude of the impact of human activity on the climate and that the planet will continue to warm if no action is taken.
Dr. Wohl, of UEA's Centre for Ocean and Atmospheric Sciences and one of the lead authors, said, "This is the climatic element with the greatest cooling capacity, but also the least understood. We knew methanethiol was coming out of the ocean, but we had no idea about how much and where. We also did not know it had such an impact on climate.
"Climate models have greatly overestimated the solar radiation actually reaching the Southern Ocean, largely because they are not capable of correctly simulating clouds. The work done here partially closes the longstanding knowledge gap between models and observations."
With this discovery, scientists can now represent the climate more accurately in models that are used to make predictions of +1.5 ºC or +2 ºC warming, a huge contribution to policy-making.
"Until now, we thought that the oceans emitted sulfur into the atmosphere only in the form of dimethyl sulfide, a residue of plankton that is mainly responsible for the evocative smell of shellfish," said Dr. Martí Galí, a researcher at the ICM-CSIC and another of the main study authors.
Dr. Wohl added, "Today, thanks to the evolution of measurement techniques, we know that plankton also emit methanethiol, and we have found a way to quantify, on a global scale, where, when and in what quantity this emission occurs. Knowing the emissions of this compound will help us to more accurately represent clouds over the Southern Ocean and calculate more realistically their cooling effect."
The researchers gathered all the available measurements of methanethiol in seawater, added those they had made in the Southern Ocean and the Mediterranean coast, and statistically related them to seawater temperature, obtained from satellites.
This allowed them to conclude that annually and on a global average, methanethiol increases known marine sulfur emissions by 25%.
"It may not seem like much, but methanethiol is more efficient at oxidizing and forming aerosols than dimethyl sulfide and, therefore, its climate impact is magnified," said co-lead Dr. Julián Villamayor, a researcher at IQF-CSIC.
The team also incorporated the marine emissions of methanethiol into a state-of-the-art climate model to assess their effects on the planet's radiation balance. It showed that the impacts are much more visible in the Southern Hemisphere, where there is more ocean and less human activity, and therefore the presence of sulfur from the burning of fossil fuels is lower.
An artist's impression shows the four spacecraft of the Magnetospheric Multiscale Mission, which fly in a tetrahedral formation and gather information about the microphysics of reconnecting magnetic-field lines and the associated processes.
Credit: NASA/GSFC
A small team of astrophysicists at the University of California, Los Angeles, working with colleagues from the University of Texas at Dallas and the University of Colorado, Boulder, has found evidence that Alfvén waves in space plasmas speed up ion beams, resulting in the creation of small-scale acoustic waves that in turn generate heat in the magnetosphere.
In their study, published in the journal Physical Review Letters, the group used data from the four-spacecraft Magnetospheric Multiscale (MMS) mission that took place in 2015 to prove a theory about heat generation in the magnetosphere.
For several years, astronomers have been studying the impact of the solar wind striking the magnetopause, which defines the outer edges of the magnetosphere. Prior research has shown that as the solar wind arrives, Alfvén waves are generated and the resulting energy heats up the plasma in the magnetosphere. However, the plasma there is too thin to result in a cascade.
To explain what happens, researchers have theorized that Alfvén waves speed up the ion beams, resulting in the creation of acoustic waves, which in turn generate heat. In this new effort, the researchers found evidence of such a chain of events, backing up the theories.
The researchers analyzed data from MMS. The unique venture involved four spacecraft that flew together in a special configuration through the magnetosphere above regions of the Earth experiencing dusk. This allowed the craft to observe large-scale topical transformations and the movement of an Alfvén wave. The configuration also allowed the spacecraft to monitor the motion of the ions in the surrounding plasma.
Such data, the research team discovered, could be used to prove a theory suggesting that heat generated by ion beams was the means by which Alfvén waves were converted to heat.
Propagation characteristics of Alfvén waves and IAWs in the spatiotemporal domain in the simulation.
Credit: arXiv: DOI: 10.48550/arxiv.2406.14782
The instruments aboard the spacecraft showed that magnetic pressure variation in the Alfvén waves was synched with ion density fluctuations and the surrounding electric field. They also showed the speed of the ion beams matched those of the Alfvén wave.
Confident that the data had proven theories surrounding heat generation in the magnetosphere, the researchers created simulations of the action as it unfolded. The simulations matched both the theory and the observations they had made.
The relationship between cranial capacity, body size, and time both within- and between-species.
Credit: Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2409542121
Modern humans, Neanderthals, and other recent relatives on our human family tree evolved bigger brains much more rapidly than earlier species, a new study of human brain evolution has found.
Scientists from the University of Reading, the University of Oxford and Durham University found that brain size increased gradually within each ancient human species rather than through sudden leaps between species. The research, published November 26 in the Proceedings of the National Academy of Sciences, overturns long-standing ideas about human brain evolution.
The team assembled the largest-ever dataset of ancient human fossils spanning 7 million years and used advanced computational and statistical methods to account for gaps in the fossil record. These innovative approaches provided the most comprehensive view yet of how brain size evolved over time.
Professor Chris Venditti, co-author of the study from the University of Reading, said, "This study completely changes our understanding of how human brains evolved. It was previously thought that brain size jumps dramatically between species, like new upgrades between the latest computer models. Our study instead shows a steady, incremental 'software update' happening within each species over millions of years."
The research challenges old ideas that some species, like Neanderthals, were unchanging and unable to adapt and instead highlights gradual and continuous change as the driving force behind brain size evolution.
Dr. Thomas Puschel, lead author now at Oxford University, said, "Big evolutionary changes don't always need dramatic events. They can happen through small, gradual improvements over time, much like how we learn and adapt today."
Brains, bodies, and evolutionary scale
The researchers also uncovered a striking pattern: While larger-bodied species generally had bigger brains, the variation observed within an individual species did not consistently correlate with body size. Brain size evolution across long evolutionary timescales extending millions of years is therefore shaped by different factors to those observed within individual species—highlighting the complexity of evolutionary pressures on brain size.
Dr. Joanna Baker, co-author from the University of Reading, said, "Why and how humans evolved large brains is a central question in human evolution. By studying brain and body size in various species over millions of years, we reveal that our hallmark large brains arose primarily from gradual changes within individual species."
3D reconstruction of the fossil skull of the sub-adult early Homo from the Dmanisi site in Georgia.
The green, orange, and red colors represent the preserved teeth (imaged respectively with the synchrotron at 5um, with the synchrotron at 47um, and with an industrial scanner at 250um).
The blue teeth are missing ones added by mirroring their symmetrical counterparts.
The purple first lower incisors have not been recovered, and have been extrapolated form the second lower incisor.
Credit: ESRF/Paul Tafforeau, Vincent Beyrand
Recent research challenges the theory that long childhood in humans is due to large brain sizes. Instead, analysis of early Homo fossil teeth suggests that prolonged development was necessary for enhanced cultural learning and knowledge sharing, which later contributed to larger brains and extended lifespans.
Compared to the great apes, humans have an exceptionally long childhood. During this period, parents and other adults contribute to their physical and cognitive development, ensuring they acquire all the cognitive skills necessary for thriving in the complex social environments of human groups.
The prevailing theory has been that the extended growth period of modern humans evolved as a consequence of the increase in brain volume, which requires substantial energy resources to grow. However, a new study on the dental growth of an exceptional fossil suggests the ‘big brain – long childhood’ hypothesis may need to be revised.
Fossil of the near-adult Homo from the Dmanisi site in Georgia, dated to around 1.77 million years ago, scanned at the European synchrotron (ESRF).
Credit: Georgian National Museum
Teeth Are the Key
The study, conducted by scientists from the University of Zurich (Switzerland), the European Synchrotron Radiation Facility (ESRF, Grenoble, France), and the Georgian National Museum (Georgia) and published in Nature, used synchrotron imaging to study the dental development of a near-adult fossil of early Homo from the Dmanisi site in Georgia, dated to around 1.77 million years ago.
“Childhood and cognition do not fossilize, so we have to rely on indirect information. Teeth are ideal because they fossilize well and produce daily rings, in the same way that trees produce annual rings, which record their development,” explains Christoph Zollikofer from the University of Zurich and the first author of the publication.
“Dental development is strongly correlated with the development of the rest of the body, including brain development. Access to the details of a fossil hominid’s dental growth therefore provides a great deal of information about its general growth,” adds Paul Tafforeau, scientist at the ESRF and co-author of the study.
https://www.youtube.com/watch?v=Eg3hjfvveuA
3D reconstruction of the fossil skull of the sub-adult early Homo from the Dmanisi site in Georgia.
The green, orange and red colors represent the preserved teeth (imaged respectively with the synchrotron at 5um, with the synchrotron at 47um, and with an industrial scanner at 250um). The blue teeth are missing ones added by mirroring their symmetrical counterparts. The purple first lower incisors have not been recovered, and have been extrapolated form the second lower incisor.
Then the right upper canine is shown at 5um resolution to illustrate the visibility of growth lines on its surface, as well as on virtual slices in its enamel and dentine.
A second level of zoom is done to reach the 0.7umm resolution that shows the daily line increments in enamel.
All the teeth are then virtually extracted from the skull and disposed in order to show the final dentition state at the death of this individual.
Based on the dental increments observed in all the teeth, a virtual growth series has been computed every 6 months from the birth to the death of this sub-adult individual which occurred at 11.42 years. Credit: ESRF/Paul Tafforeau, Vincent Beyrand
18 Years of Research
The project was launched in 2005, following the initial success of non-destructive analyses of dental microstructures using phase contrast synchrotron tomography at the ESRF. This technique enabled scientists to create virtual microscopic slices through the teeth of this fossil. The exceptional quality of preservation of the growth structures in this specimen has made it possible to reconstruct all the phases of its dental growth, from birth to death, with unprecedented precision. In a way, the scientists have virtually regrown the teeth of this hominid.
This project took almost 18 years, from its initial conception in 2005 to finalizing the results in 2023. The scientists scanned the teeth for the first time in 2006, and the first results on the fossil’s age at death were obtained in 2007.
“We expected to find either dental development typical of early hominids, close to that of the great apes, or dental development close to that of modern humans. When we obtained the first results, we couldn’t believe what we saw, because it was something different that implied faster molar crown growth than in any other fossil hominin or living great ape,” explains Tafforeau.
Over the next few years, five experiments and four complete analyses using different approaches were carried out as technical advances were made in dental synchrotron imaging. With the results all pointing in the same direction and potentially having a strong impact on the ‘big brain – long childhood’ hypothesis, the scientists had to think outside the box to understand this fossil. “It’s been a slow maturation, both technically and intellectually, to finally arrive at the hypothesis we are publishing today,” concludes Tafforeau.
Paul Tafforeau and Vincent Beyrand at the European Synchrotron (ESRF), scanning teeth. Credit: ESRF/Stef Candé
Evolutionary Implications of Dental Development Patterns
“The results showed that this individual died between 11 and 12 years of age, when his wisdom teeth had already erupted, as is the case in great apes at this age,” explains Vincent Beyrand, co-author of the study. However, the team found that this fossil had a surprisingly similar tooth maturation pattern to humans, with the back teeth lagging behind the front teeth for the first five years of their development.
“This suggests that milk teeth were used for longer than in the great apes and that the children of this early Homo species were dependent on adult support for longer than those of the great apes,” explains Marcia Ponce de León from the University of Zurich and co-author of the study. “This could be the first evolutionary experiment of prolonged childhood.”
Challenging Established Evolutionary Theories
This is where the ‘big brain – long childhood’ hypothesis is tested. Early Homo individuals did not have much bigger brains than great apes or australopithecines, but they possibly lived longer. In fact, one of the skulls discovered at Dmanisi was that of a very old individual with no teeth left during its last few years of life. “The fact that such an old individual was able to survive without any teeth for several years indicates that the rest of the group took good care of him,” comments David Lordkipadnize of the National Museum of Georgia and co-author of the study. The older individuals have the greatest experience, so their role in the community likely was to pass on their knowledge to the younger individuals. This three-generation structure is a fundamental aspect of the transmission of culture in humans.
It is well known that young children can memorize an enormous amount of information thanks to the plasticity of their immature brains. However, the more information they have to memorize, the longer it takes.
This is where the new hypothesis comes in. Children’s growth would have slowed down at the same time as cultural transmission increased, making the amount of information communicated from old to young increasingly important. This transmission would have enabled them to make better use of available resources while developing more complex behaviors and would thus have given them an evolutionary advantage in favor of a longer childhood (and probably a longer lifespan).
Once this mechanism was in place, natural selection would have acted on cultural transmission and not just on biological traits. Then, as the amount of information to be transmitted increased, evolution would have favored an increase in brain size and a delay in adulthood, allowing us both to learn more in childhood and to have the time to grow a larger brain despite limited food resources.
Therefore, it may not have been the evolutionary increase in brain size that led to the slowdown in human development but the extension of childhood and the three-generation structure that favored bio-cultural evolution. These mechanisms, in turn, led to an increase in brain size, a later adulthood, and a longer life span. Studying the teeth of this exceptional fossil could therefore encourage researchers to reconsider the evolutionary mechanisms that led to our own species, Homo sapiens.
The snowfall caused flight cancellations and delays.
South Korea's capital was blanketed Wednesday by the heaviest November snowfall since records began over a century ago, the weather agency said.
The Korea Meteorological Administration said 16.5 centimeters (6.5 inches) of snow fell by 7:00 am (2200 GMT Tuesday), compared to Seoul's previous record of 12.4 cm on November 28, 1972.
Coincidentally being the first snow of the season in Seoul, it is the highest figure in November since the agency set up nationwide observation posts in 1907.
A heavy snow warning urged residents to "refrain from operating vehicles and engaging in outdoor activities" and to "beware of falling trees".
Such warnings are issued when snowfall accumulates to 20 cm or more within 24 hours.
As heavy snow fell nationwide, multiple accidents occurred due to vehicles sliding on icy roads, though no major injuries have been reported.
Falling trees caused power outages, affecting more than 150 households around Seoul in the morning.
Main roads were closed for maintenance, leading to severe traffic congestion, while at least 22 domestic flights were cancelled, and several others were delayed, according to the transport ministry.
President Yoon Suk Yeol called on officials to "minimize potential damage and public inconvenience caused by the snow," as the heavy snowfall is expected to continue until Thursday morning.
The heavy snowfall was caused by the "significant temperature difference between the sea surface and the cold air," Youn Ki-han, director at Seoul's Meteorology Forecast Division, told AFP.
"Over the West Sea, moisture forms, and when cold air from the north moves down as it typically does, if the West Sea is also cold as in previous years, the temperature difference is smaller," said Youn.
However, due to the unusually warm temperatures in recent weeks, this difference became more pronounced.
Another factor behind the heavy snowfall, Youn added, is that "the strong snow was consistently carried by the westerly winds, pushing it into the Seoul metropolitan area."
"Snow kept falling in the same areas repeatedly, leading to greater accumulation."
Up to 20 cm of additional snowfall is expected to fall around the capital, according to the weather agency.
The cells in our bodies are like bustling cities, running on an iron-powered system that uses hydrogen peroxide (H₂O₂) not just for cleaning up messes but also for sending critical signals. Normally, this works fine, but under stress, such as inflammation or a burst of energy use, oxidative stress damages cells at the genetic level.
This is because iron and H₂O₂ react in what's known as the Fenton reaction, producing hydroxyl radicals, destructive molecules that attack DNA and RNA indiscriminately. But there's a catch. In the presence of carbon dioxide—that pesky gas disrupting global climate systems—our cells gain a secret weapon in the form of bicarbonate which helps keep pH levels balanced.
A team of University of Utah chemists has discovered that bicarbonate doesn't just act as a pH buffer but also alters the Fenton reaction itself in cells. Instead of producing chaotic hydroxyl radicals, the reaction instead makes carbonate radicals, which affect DNA in a far less harmful way, according to Cynthia Burrows, a distinguished professor of chemistry and senior author of a study.
Their paper is being published this week in the Proceedings of the National Academy of Sciences and is currently available on the bioRxiv preprint server.
"So many diseases, so many conditions have oxidative stress as a component of disease. That would include many cancers, effectively all age-related diseases, a lot of neurological diseases," Burrows said. "We're trying to understand cells' fundamental chemistry under oxidative stress. We have learned something about the protective effect of CO₂ that I think is really profound."
Co-authors include Aaron Fleming, a research associate professor, and doctoral candidate Justin Dingman, both members of the Burrows Laboratory.
Without bicarbonate or CO₂ present in experimental DNA oxidation reactions, the chemistry is also different. The free radical species generated, hydroxyl radical, is extremely reactive and hits DNA like a shotgun blast, causing damage everywhere, Burrows said.
In contrast, her team's findings show that the presence of bicarbonate from dissolved CO₂ changes the reaction to make a milder radical striking only guanine, the G in our four-letter genetic code.
"Like throwing a dart at the bullseye where G is the center of the target," Burrows said. "It turns out that bicarbonate is a major buffer inside your cells. Bicarbonate binds to iron, and it completely changes the Fenton reaction. You don't make these super highly reactive radicals that everyone's been studying for decades."
What do these findings mean for science? Potentially a lot.
For starters, the team's discovery shows cells are a lot smarter than previously imagined, which could reshape how we understand oxidative stress and its role in diseases like cancer or aging.
But it also raises the possibility that many scientists studying cell damage have been conducting laboratory experiments in ways that don't reflect the real world, rendering their results suspect, Burrows said. Chemists and biologists everywhere grow cells in a tissue culture in an incubator set to 37°C, or body temperature. In these cultures, carbon dioxide levels are raised to 5%, or about 100 times more concentrated than what's found in the atmosphere.
The elevated CO₂ recreates the environment the cells normally inhabit as they metabolize nutrients; however, it is lost when researchers start their experiments outside the incubator.
"Just like opening up a can of beer. You release the CO₂ when you take your cells out of the incubator. It's like doing experiments with a day-old glass of beer. It's pretty flat. It has lost the CO₂, its bicarbonate buffer," Burrows said. "You no longer have the protection of CO₂ to modulate the iron-hydrogen peroxide reaction."
She believes bicarbonate needs to be added to ensure reliable results from such experiments.
"Most people leave out bicarbonate/CO₂ when studying DNA oxidation because it is difficult to deal with the constant outgassing of CO₂," Burrows said. "These studies suggest that to get an accurate picture of DNA damage that occurs from normal cellular processes like metabolism, researchers need to be careful to mimic the proper conditions of the cell and add bicarbonate, i.e., baking powder!"
Burrows anticipates her study could result in unintended outcomes that may someday benefit research in other areas. Her lab is hoping to study the effect of CO₂ on people confined to enclosed spaces, such as inside of space capsules and submarines.
"You've got astronauts in a capsule living and breathing, and they are exhaling CO₂. The problem is how much CO₂ can they safely handle in their atmosphere? One of the things we found is that, at least in terms of tissue culture, CO₂ does have a protective effect from some of the radiation damage these astronauts might experience.
"So what you might want to do is push up that CO₂ level. You certainly don't want to go very high, but having it slightly higher might actually have a protective effect against radiation, which generates hydroxyl radicals."
