Browse Articles

Darkness and body size shaped end-Cretaceous marine extinction patterns

Abstract The Chicxulub asteroid impact at the Cretaceous–Paleogene (K–Pg) boundary (66 Ma) is thought to have caused the extinction of around 75% of species in the fossil record by triggering catastrophic environmental changes 1 . However, despite decades of research, the mechanisms linking the environmental changes to the selective extinction patterns observed in the marine fossil record remain unresolved. Here we use a global trait-based ecosystem model 2,3 to establish this causality for the marine plankton community beyond the fossilized groups. Our model simulates diversity dynamics during the initial 100 years after the K–Pg boundary and represents explicitly extinction based on biomass thresholds that scales with body size. Under K–Pg climatic forcings, the model reproduces successfully key observed extinction patterns, including the high vulnerability of planktic foraminifera and other zooplankton, the survival of small mixotrophs 4 and phytoplankton 5,6 , and potential for reduced diversity loss in high-latitude settings 7 . Our analysis suggests that impact-driven darkness and body-size-dependent extinction thresholds drove most of the observed extinction patterns. These results suggest that plankton ecologies enhance survival through differences in energy demand and acquisition. Our study bridges the gap between fossil evidence of extinction patterns and the K–Pg impact winter hypothesis, highlighting the value of trait-based models for understanding past biodiversity crises.

Constraining an exoplanet’s magnetic field using star-planet interactions

Theory predicts that a planet with a sufficiently strong magnetic field orbiting close to its host star could induce star-planet magnetic interactions. This is potentially observable as an optical or radio stellar activity signal synchronized with the planet’s orbital period. We analyzed 18 years of high-resolution optical spectroscopy of GJ 436, a low-mass star orbited by a Neptune-sized exoplanet on a polar eccentric orbit. Stellar activity indicators show enhancements at a period corresponding to the exoplanet orbit, modulated by stellar rotation, and the star’s 8-year magnetic cycle. We interpret this as a signal of star-planet magnetic interaction. Using a geometric model, we reproduced these periods if GJ 436 b has a magnetic field strength of 6 to 110 gauss.

Epigenetic and 3D genome reprogramming during the aging of the human hippocampus

Changes in gene expression have been observed in the aging human brain, but our understanding of the underlying regulatory mechanisms remains limited. To unravel these complexities, we analyzed single-nucleus gene expression, chromatin accessibility, DNA methylation, and three-dimensional (3D) chromatin architecture from human hippocampal tissues spanning the adult lifespan. We identified both linear and nonlinear dynamic gene regulatory programs during aging. Between the ages of 50 to 75, embryonic yolk sac–derived microglia were depleted and replaced by cells resembling peripheral blood monocyte–derived microglia. Hippocampal astrocytes decreased substantially with age, including those regulating synaptic transmission. Across cell types, 3D genome architecture underwent global erosion. Our analysis provides insights for how altered gene regulatory programs promote cell type–specific aging phenotypes in the human brain.

Step geometry–guided growth of rhombohedral graphene

Rhombohedral (ABC)–stacked graphene has emerged as a platform for exploring correlated and topological physics. However, its large-scale, pure-phase synthesis has been hindered by intrinsic thermodynamic metastability and kinetic instability. In this work, we introduce a step geometry–guided epitaxial strategy to deterministically control interlayer slip, enabling the synthesis of pure-phase rhombohedral graphene. Using this approach, we obtained pure (phase purity > 99%) rhombohedral graphene with an area reaching 160 micrometers by 80 micrometers and thickness ranging from ~15 layers to ~120 nanometers. The resulting samples establish the first comprehensive reference dataset of Raman fingerprints and intrinsic band structures from few-layer films to ~200-layer bulk. Electronic transport measurements reveal a layer-antiferromagnetic state and the quantum anomalous Hall effect, enabling scalable exploration of next-generation quantum science and technology applications.

Redesigning algorithms to intervene on social norm misperceptions during a national election

Brazil’s environmental governance at risk

Genome in motion: Mapping the nucleus in health

The global biogeography of passerine songs

Although bird songs are classic models for understanding the evolution of vocal communication, their global diversity has long made the development of a unifying framework challenging. By analyzing the acoustic architecture of songs from more than 3000 passerine species worldwide, we show that this acoustic space can be structured around eight elemental motifs. The differential use of these motifs is driven by a combination of species’ biological traits (social organization, morphology, and mating system) and the physics of sound propagation. In tropical rainforests, environmental filtering for transmission efficiency favors structurally simple motifs, such as flat whistles. Conversely, in temperate regions, where high population densities facilitate close-range communication and short breeding seasons intensify sexual selection, the balance shifts toward complex, information-rich motifs, such as ultrafast trills, despite their susceptibility to acoustic degradation. Ultimately, the global geography of birdsong reflects a spatially varying equilibrium between physical environmental constraints and the biological drive for complex communication.

Late-stage functionalization with strain-release warheads enables tunable covalent inhibition

Covalent inhibition continues to gain momentum as a strategy for selective protein modulation in both therapeutic and chemical biology contexts. Covalent reactive groups (CRGs) typically engage nucleophilic residues such as cysteine, resulting in targeted protein inactivation. However, common electrophiles such as acrylamides often suffer from nonselective reactivity, leading to off-target effects and toxicity. To overcome these limitations, we developed a modular sulfur(IV) reagent platform for the mild, late-stage installation of sulfonyl- and sulfonimidoyl-bicyclobutane motifs with complete cysteine selectivity. This methodology enables access to diverse sulfur(VI) CRGs with tunable strain-release reactivity. Incorporation into US Food and Drug Administration–approved covalent inhibitors demonstrated effective bioisosteric replacement of acrylamides and the potential of strain-release CRGs for selective protein targeting. Preclinical studies in mice have validated this approach, highlighting its promise for next-generation covalent drug design.

Crush-resistant air sacs allow insect larvae to exploit aquatic habitats at extreme depth

The absence of aquatic insects from pelagic marine habitats has been attributed to their air-filled tracheal respiratory system, which could implode at depth while undertaking diel vertical migrations to escape predatory fish. However, we found that the aquatic larvae of the lake fly Chaoborus edulis in Lake Malawi have modified their tracheal system into reinforced buoyancy-regulating air-filled sacs, allowing them to escape predatory fish by undertaking these migrations well over 200 meters deep into the lake’s anoxic hypolimnion during the day. The crush depth of their air sacs increases with each instar, with final instars resisting implosion at depths greater than half a kilometer. Contrary to expectations, these insects adapt to the extreme hydrostatic pressures of deep-water habitats, allowing them to coexist with pelagic fish.

A fatal reaction

A cutting-edge gene-editing trial in China went disastrously wrong. A family wants accountability

Seafood biosecurity gaps threaten biodiversity

Oldest known Mars rock offers glimpse of planet’s watery youth

Teghaza meteorite hints at surprisingly Earth-like crust and shows Mars was already losing its water 4.1 billion years ago

Dose-dependent sensitivity of human three-dimensional chromatin to a heart disease–linked transcription factor

Dosage-sensitive transcription factors (TFs) underlie altered gene regulation in human developmental disorders, and cell type–specific gene regulation is linked to the reorganization of three-dimensional (3D) chromatin during cellular differentiation. In this work, we show dose-dependent regulation of chromatin organization by the congenital heart disease (CHD)–linked, lineage-restricted TF TBX5 in human cardiomyocyte differentiation. Genome organization, including compartments, topologically associated domains, and chromatin loops, was sensitive to reduced TBX5 dosage in a human model of CHD, with variations in response across individual cells. Cohesin binding was reduced at TBX5-bound enhancer elements in a TBX5 dose-dependent manner, providing a potential mechanism for disrupted loop formation. These results highlight the importance of lineage-restricted TF dosage in cell type–specific 3D chromatin dynamics, suggesting a mechanism for TF-dependent disease.

Invasive species’ environmental impacts are more severe in the Global South

Invasive alien species (IAS) are a major threat to biodiversity, yet their impact distribution remains poorly understood. Global biodiversity assessments suggest the highest impacts in wealthy countries of the Global North, but this is only inferred from IAS numbers, reflecting research bias. Using a new global database of standardized impact measures, we calculated average impact severity per country and found that it is higher in the Global South despite more than twice as many reports in the Global North. Weak governance and limited management capacity are the main drivers of high impact severity. Emerging economies with rapid economic growth but poor governance are particularly vulnerable. Failure to recognize the Global South as facing the highest IAS impacts diverts attention away from the most threatened regions.

Protect and expand ocean observation systems

Reconfigurable mmWave microchips co-integrating hBN switches on GaN

University science in the US needs a coherent plan

The Trump administration continues to degrade America’s scientific establishment, causing widespread harm to the country’s broader interests and well-being. Last week, the Association of American Universities reported that graduate student enrollment in major research universities, which award half of all doctorate degrees in the United States, is down 15% compared to a year ago. And no wonder, considering the effect of recent immigration policies that deter international students and the financial uncertainties that universities are facing given the unpredictable nature of federal funding. The ability to support new doctoral students depends heavily on research grants, and any responsible administrator would be cautious about making commitments to students they can’t keep. This is discouraging to the scientific community but should be alarming to everyone.

Human body single-cell atlas of three-dimensional genome organization and DNA methylation

Higher-order chromatin structure and DNA methylation are critical for gene regulation, but how these vary across the human body remains unclear. We performed multiomic profiling of three-dimensional (3D) genome structure and DNA methylation for 86,689 single nuclei across 16 tissues, identifying 35 major and 206 cell subtypes. We revealed extensive changes in CG and non-CG methylation across cell types and characterized 3D chromatin structure at an unprecedented cellular resolution. Extensive discrepancies exist between cell types delineated by DNA methylation and genome structure, which indicates that the role of distinct epigenomic features in maintaining cell identity may vary by lineage. This study expands our understanding of the diversity of DNA methylation and chromatin structure and offers a reference for exploring gene regulation in human health and disease.

Climate scientists sharpen tools for linking global warming to extreme weather

National Academies report says more rigorous results will boost confidence in fast-growing field