Category: 7. Science

A new study reveals that humans were extensively using fire to modify landscapes as far back as 50,000 years ago. That’s at least 10,000 years earlier than previously believed. Scientists uncovered this clue in a 300,000-year-old sediment core extracted from the East China Sea.

The core contained fossilized charcoal, microscopic remnants of plant matter burned but not fully consumed. Known as pyrogenic carbon, these particles drifted into the sea via rivers over tens of thousands of years. They serve as an enduring record of fire on land.

A Fire Signature That Outpaced Climate

The research team, led by Dr. Debo Zhao from the Institute of Oceanology at the Chinese Academy of Sciences, found something unexpected. Around 50,000 years ago, levels of pyrogenic carbon suddenly spiked. The timing didn’t line up with known climate patterns. It suggested something new was at play.

“Our findings challenge the widely held belief that humans only began influencing geological processes in the recent past—during the last Ice Age and the ensuing Holocene,” said Dr. Zhao.

Instead, the evidence points to humans (modern Homo sapiens) as the likely culprits. This timeline aligns with archaeological records showing a rapid expansion of Homo sapiens across Eurasia, Southeast Asia, and into Australia between 70,000 and 50,000 years ago.

In each of these regions, fire activity began to rise dramatically. But this wasn’t wildfire season. These were intentional flames.

A Record of Ice and Fire

As the climate cooled during glacial periods, fire became indispensable. It helped early humans cook food, stay warm, fend off predators, and migrate into colder, more challenging landscapes. But it also transformed those landscapes.

“Humans likely began shaping ecosystems and the global carbon cycle through their use of fire even before the Last Ice Age,” said Dr. Stefanie Kaboth-Bahr, a paleontologist at Freie Universität Berlin and coauthor of the study.

The fire’s effects were lasting. Burning vegetation releases carbon into the atmosphere. Doing this repeatedly over large areas eventually warms the planet, albeit by a very tiny amount compared to present-day industrial activity.

The discovery suggests that humans began influencing the Earth’s carbon cycle tens of thousands of years earlier than scientists had assumed. “Even during the Last Glaciation, the use of fire had probably started to reshape ecosystems and carbon fluxes,” added Professor Wan Shiming, another corresponding author.

The Global Signature of Humanity’s First Flames

The researchers compared the East Asia findings with data from Europe, Southeast Asia, and Papua New Guinea–Australia. The same pattern emerged in each region: a sudden uptick in fire activity starting roughly 50,000 years ago.

Crucially, this fire surge appeared even where natural conditions—like rainfall or lightning—wouldn’t account for such increases. Something else had to be driving it. The clearest candidate: humans.

The study also suggests that this early fire use was systematic enough to leave a lasting mark on Earth’s geological record—what some scientists refer to as the pyroscape, the legacy of fire through time.

This study underscores how early and profoundly humans began altering the planet. It challenges the idea that the Anthropocene (our proposed new geological epoch) begins with agriculture or the Industrial Revolution. Instead, the spark might have been struck much earlier, with the simple but powerful act of lighting a fire.

Kaboth-Bahr’s research is part of a larger initiative called The Burning Question, which investigates the role of fire in shaping ecosystems across Eastern Africa. Supported by the German Research Foundation and partners in Ethiopia, the project seeks to understand fire’s ecological, climatic, and cultural significance over the last 600,000 years.

The findings appeared in the Proceedings of the National Academy of Sciences.

An international research team led by scientists from the University of Vienna has uncovered new insights into how specialized cell types and communication networks at the interface between mother and fetus evolved over millions of years. These discoveries shed light on one of nature’s most remarkable innovations – the ability to sustain a successful pregnancy. The findings have just been published in Nature Ecology & Evolution.

Pregnancy that lasts long enough to support full fetal development is a hallmark evolutionary breakthrough of placental mammals – a group that includes humans. At the center of this is the fetal-maternal interface: the site in the womb where a baby’s placenta meets the mother’s uterus, and where two genetically distinct organisms – mother and fetus – are in intimate contact and constant interaction. This interface has to strike a delicate balance: intimate enough to exchange nutrients and signals, but protected enough to prevent the maternal immune system from rejecting the genetically “foreign” fetus.

To uncover the origins and mechanisms behind this intricate structure, the team analyzed single-cell transcriptomes – snapshots of active genes in individual cells – from six mammalian species representing key branches of the mammalian evolutionary tree. These included mice and guinea pigs (rodents), macaques and humans (primates), and two more unusual mammals: the tenrec (an early placental mammal) and the opossum (a marsupial that split off from placental mammals before they evolved complex placentas).

A cellular “atlas of mammal pregnancy”

By analyzing cells at the fetal-maternal interface, the researchers were able to trace the evolutionary origin and diversification of the key cell types involved. Their focus was on two main players: placenta cells, which originate from the fetus and invade maternal tissue, and uterine stromal cells, which are of maternal origin and respond to this invasion.

Using molecular biology tools, the team identified distinct genetic signatures – patterns of gene activity unique to specific cell types and their specialized functions. Notably, they discovered a genetic signature associated with the invasive behavior of fetal placenta cells that has been conserved in mammals for over 100 million years. This finding challenges the traditional view that invasive placenta cells are unique to humans, and reveals instead that they are a deeply conserved feature of mammalian evolution. During this time, the maternal cells weren’t static, either. Placental mammals, but not marsupials, were found to have acquired new forms of hormone production, a pivotal step toward prolonged pregnancies and complex gestation, and a sign that the fetus and the mother could be driving each other’s evolution.

Cellular dialogue: Between cooperation and conflict

To better understand how the fetal-maternal interface functions, the study tested two influential theories about the evolution of cellular communication between mother and fetus.

The first, the “Disambiguation Hypothesis,” predicts that over evolutionary time, hormonal signals became clearly assigned to either the fetus or the mother – a possible safeguard to ensure clarity and prevent manipulation. The results confirmed this idea: certain signals, including WNT proteins, immune modulators, and steroid hormones, could be clearly traced back to one source tissue.

The second, the “Escalation Hypothesis” (or “genomic Conflict”), suggests an evolutionary arms race between maternal and fetal genes – with, for example, the fetus boosting growth signals while the maternal side tries to dampen them. This pattern was observed in a small number of genes, notably IGF2, which regulates growth. On the whole, evidence pointed to fine-tuned cooperative signaling.

These findings suggest that evolution may have favored more coordination between mother and fetus than previously assumed. The so-called mother-fetus power struggle appears to be limited to specific genetic regions. Rather than asking whether pregnancy as a whole is conflict or cooperation, a more useful question may be: where is the conflict?”

Daniel J. Stadtmauer, lead author of the study and researcher at the Department of Evolutionary Biology, University of Vienna

Single-cell analysis: A key to evolutionary discovery

The team’s discoveries were made possible by combining two powerful tools: single-cell transcriptomics – which captures the activity of genes in individual cells – and evolutionary modeling techniques that help scientists reconstruct how traits might have looked in long-extinct ancestors. By applying these methods to cell types and their gene activity, the researchers could simulate how cells communicate in different species, and even glimpse how this dialogue has evolved over millions of years.

“Our approach opens a new window into the evolution of complex biological systems – from individual cells to entire tissues,” says Silvia Basanta, co–first author and researcher at the University of Vienna. The study not only sheds light on how pregnancy evolved, but also offers a new framework for tracking evolutionary innovations at the cellular level – insights that could one day improve how we understand, diagnose, or treat pregnancy-related complications.

The research was conducted in the labs of Mihaela Pavličev at the Department of Evolutionary Biology, University of Vienna, and Günter Wagner at Yale University. Wagner is Professor Emeritus at Yale and a Senior Research Fellow at the University of Vienna. The study was supported by the John Templeton Foundation and the Austrian Science Fund (FWF).

There is no better excuse to travel than to see a total solar eclipse, and the next one happens on Aug. 12, 2026. Although a total solar eclipse is an unforgettable experience, totality lasts only a few minutes. So what do you do before and after the eclipse?

Boredom won’t be a problem for the 2026 total solar eclipse, with some truly spectacular locations and popular vacation areas in or close to the path of totality. From Greenland to Spain, there are myriad unique experiences and off-the-beaten-track itineraries that offer much more than nature’s greatest spectacle.

The cycle of metals between the gas and the dust phases in the neutral interstellar medium (ISM) is an integral part of the baryon cycle in galaxies.

The resulting variations in the abundance and properties of interstellar dust have important implications for how accurately we can trace the chemical enrichment of the universe over cosmic time.

Multi-object UV spectroscopy with HWO can provide the large samples of abundance and dust depletion measurements needed to understand how the abundance and properties of interstellar dust vary within and between galaxies, thereby observationally addressing important questions about chemical enrichment and galaxy evolution.

Medium-resolution (R~50,000) spectroscopy in the full UV range (950-3150 A) toward massive stars in Local Volume galaxies (D < 10 Mpc) will enable gas- and dust-phase abundance measurements of key elements, such as Fe, Si, Mg, S, Zn. These measurements will provide an estimate of how the dust abundance varies with environment, in particular metallicity and gas density.

However, measuring the carbon and oxygen contents of dust requires very high resolution (R > 100,000) and high signal-to-noise (S/N > 100) owing to the non-saturated UV transitions for those elements being extremely weak. Since carbon and oxygen in the neutral ISM contribute the largest metal mass reservoir for dust, it is critical that the HWO design include a grating similar to the HST STIS H gratings providing very high resolution, as well as FUV and NUV detectors capable of reaching very high S/N.

Julia Roman-Duval, Yumi Choi, Mederic Boquien

Comments: 12 pages; 6 figures; will be published in ASP conference proceedings of the HWO2025 conference
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2507.00201 [astro-ph.GA] (or arXiv:2507.00201v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2507.00201
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Submission history
From: Julia Roman-Duval
[v1] Mon, 30 Jun 2025 19:10:27 UTC (663 KB)
https://arxiv.org/abs/2507.00201
Astrobiology

Understanding where and in what quantities essential elements for life have existed on Earth’s surface helps explain the origin and evolution of life. Phosphorus (P) is one such element, forming the backbone of DNA, RNA, and cellular membranes. On Earth’s surface, P is primarily preserved in rocks in the form of phosphate minerals. However, these phosphate minerals are generally insoluble. Therefore, scientists have long struggled to answer the question of under what conditions P could have become concentrated on the early Earth.

Now, a research team comprising Yuya Tsukamoto and Takeshi Kakegawa from Tohoku University may have found the answer. For the first time, they have uncovered geochemical and mineralogical evidence that submarine hydrothermal alteration may have been a significant source of P on the early Earth.

“We analyzed 3.455-billion-year-old basaltic seafloor rocks in drill core samples recovered from the Pilbara Craton, Western Australia, discovering that P was significantly leached from the hydrothermally altered rocks compared to the least altered rocks” with further mineralogical analyses indicating that phosphate minerals had undergone dissolution in rocks where P was depleted explains,” explains Tsukamoto. “In other words, these hydrothermal processes may have released phosphorus from the rocks into the surrounding seawater, enriching early oceans with this essential nutrient.”

Schematic image of this study. ©Tsukamoto and Kakegawa et al. — Tohoku University

The team identified that this significant dissolution was caused by two types of hydrothermal fluids: sulfidic and high-temperature fluids, and mildly acidic to alkaline and relatively low-temperature fluids. In particular, the latter fluids are characteristic of the Archean, reflecting a high CO₂ atmosphere at that time.

Calculations indicated that these latter fluids could contain up to 2 mM phosphate, approximately 1,000 times higher than modern seawater concentrations. Furthermore, calculations based on the study’s analytical results suggested that the annual flux of P from Archean submarine hydrothermal fluids could have been comparable to that supplied to the modern ocean by continental weathering.

“Importantly, this study provides direct evidence that submarine hydrothermal activity leached P from seafloor basaltic rocks and quantifies the potential P flux from these hydrothermal systems to the early ocean,” adds Tsukamoto. “Our findings demonstrate that hydrothermal systems could have locally supplied sufficient P to support early microbial ecosystems. These environments may have served as cradles for early life and played a significant role in the origin and evolution of life.”

The study also highlights the potential impact of hydrothermal fields not only on the seafloor but also in terrestrial settings such as hot springs. Future research on phosphate behavior in hydrothermally altered rocks through time will further reveal shifts in P cycles on the early Earth.

Details of the study were published in the journal Geochimica et Cosmochimica Acta on June 18, 2025.

Phosphate behavior during submarine hydrothermal alteration of ca. 3.455 Ga basaltic seafloor rocks from Pilbara, Western Australia, Geochimica et Cosmochimica Acta

Astrobiology

Cosmochemical studies have proposed that Earth accreted roughly 5-10% of its mass from carbonaceous (CC) material, with a large fraction delivered late via its final impactor, Theia (the Moon-forming impactor). ‘

Here, we evaluate this idea using dynamical simulations of terrestrial planet formation, starting from a standard setup with a population of planetary embryos and planetesimals laid out in a ring centered between Venus and Earth’s orbits, and also including a population of CC planetesimals and planetary embryos scattered inward by Jupiter.

We find that this scenario can match a large number of constraints, including i) the terrestrial planets’ masses and orbits; ii) the CC mass fraction of Earth; iii) the much lower CC mass fraction of Mars, as long as Mars only accreted CC planetesimals (but no CC embryos); iv) the timing of the last giant (Moon-forming) impact; and v) a late accretion phase dominated by non-carbonaceous (NC) bodies.

For this scenario to work, the total mass in scattered CC objects must have been ~ 0.2 – 0.3 M⊕ , with an embryo-to-planetesimal mass ratio of at least 8, and CC embryos in the ~ 0.01 – 0.05 M⊕ mass range.

In that case, our simulations show there are roughly 50-50 odds of Earth’s last giant impactor (Theia) having been a carbonaceous object – either a pure CC embryo or an NC embryo that previously accreted a CC embryo. Our simulations thus provide dynamical validation of cosmochemical studies.

Duarte Branco, Sean N. Raymond, Pedro Machado

Comments: 20 pages, 11 figures, to be published in Icarus
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2507.01826 [astro-ph.EP] (or arXiv:2507.01826v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2507.01826
Focus to learn more
Submission history
From: Duarte Branco
[v1] Wed, 2 Jul 2025 15:41:34 UTC (2,574 KB)
https://arxiv.org/abs/2507.01826

Astrobiology,

[Source]

Researchers at five British universities have launched the Synthetic Human Genome Project (SynHG) with an initial grant of approximately $12.6 million from Wellcome, the U.K.’s largest biomedical research charity. Unveiled on Thursday, the five-year effort is led by molecular biologist Jason W. Chin at the Medical Research Council Laboratory of Molecular Biology in Cambridge and aims to assemble an entire human chromosome, base by base, inside the lab.

Writing a genome

Instead of tweaking existing DNA with tools such as CRISPR, SynHG will attempt to “write” long stretches of code before inserting them into cultured human skin cells to study how chromosome architecture drives health and disease. The project builds on Chin’s earlier success constructing a fully synthetic E. coli genome.

The laboratory playbook blends generative-AI sequence design with high-throughput robotic assembly, allowing scientists to plan and assemble millions of DNA bases. Patrick Yizhi Cai of the University of Manchester, who oversees these methods, says the approach “leverag[es] cutting-edge generative AI and advanced robotic assembly technologies to revolutionize synthetic mammalian chromosome engineering.”

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Why experts are cautious

Geneticist Robin Lovell-Badge of London’s Francis Crick Institute emphasized the importance of understanding not only the scientific potential but also the societal values and risks involved. He warned that as research progresses, there is the possibility of creating synthetic cells that could, if used in humans, lead to tumors or produce novel infectious particles if not carefully designed. Lovell-Badge recommended that any engineered cells should include safeguards, such as inducible genetic kill switches, to ensure they can be eliminated from the body or targeted by the immune system if needed.

Sarah Norcross, director of the Progress Educational Trust, echoed the need for transparency and public engagement, highlighting that synthesizing human genomes is controversial and requires researchers and the public to be in active communication. Norcross welcomed the project’s built-in social science program, which surveys communities across Asia-Pacific, Africa, Europe and the Americas as the science unfolds and is led by social scientist Joy Yueyue Zhang, as a way to ensure that public interests and concerns are considered from the outset.

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Road ahead

Over the next five years, the consortium will iterate design–build–test cycles, aiming first for an error-free synthetic chromosome representing roughly 2% of human DNA. Alongside the laboratory milestones, the team plans to release an open-access toolkit covering both the technical and governance lessons learned.

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New drugs that target ‘zombie’ tuberculosis (TB) cells are now a step closer, thanks to a new study led by the University of Surrey, published in Scientific Reports.

Many dangerous pathogens, including the bacteria that cause TB, are capable of generating dormant, drug-tolerant cells, often described as ‘zombies’. These persister cells can survive intense antibiotic treatments by essentially playing dead. Once the drugs are gone, they ‘wake up’ and can trigger recurring, and often deadly, infections. Eliminating these zombie-like cells currently requires months of multi-drug therapy, and even then, treatment often fails, fueling relapse and the rise of antimicrobial resistance (AMR).

In the study, the Surrey team exposed a vast library of over 500,000 genetically modified TB bacteria to two commonly used antibiotics – rifampicin and streptomycin. The exposure was extended long enough that the remaining survivors were primarily persisters. By analyzing the survivors, the researchers pinpointed genes whose disruption significantly reduced the number of surviving zombie cells.

These critical genes were found to perform various roles: some weakened the protective bacterial cell wall, others activated a form of bacterial self-destruction, and still others disrupted the cell’s metabolic balance. Each of these pathways offers a potential strategy for designing new drugs that could wipe out persister cells more rapidly and effectively.

The next phase of research will focus on developing novel therapeutics that mimic these gene functions, paving the way for shorter, more successful TB treatments and a powerful new weapon in the global fight against AMR.

Tuberculosis really is the forgotten pandemic. It killed 1.3 million people last year, mostly from completely drug-sensitive strains. The problem isn’t always resistance – it’s persisters. These are a tiny group of phenotypically drug-resistant bacteria that survive antibiotic treatment and can go on to cause treatment failure.

What we found is that persister survival depends on the antibiotic used. The mechanisms aren’t shared as previously thought; they’re drug-specific. That changes how we think about targeting persisters and could shape how future TB treatments are designed.”

Dr. Suzie Hingley-Wilson, co-corresponding author of the study and Senior Lecturer in Bacteriology at the University of Surrey

Mutations in some of the genes identified in the study have been found in TB strains from patients who do not respond to treatment. This overlap suggests that the mechanisms observed in the lab reflect what is happening in real infections and may help explain why some patients relapse even when the bacteria are not resistant to the antibiotics.

Professor Johnjoe McFadden, study lead from the University of Surrey, said:

“The mechanisms involved in persistence are probably the biggest mysteries in microbiology. Their solution could revolutionize treatment for some of the most challenging diseases to treat, such as tuberculosis (TB). This groundbreaking research could lead to new drugs that target persisters, shortening treatment regimens and reducing both treatment costs and the burden of antimicrobial resistance (AMR).”

The study was supported by the Medical Research Council and the Biotechnology and Biological Sciences Research Council.