A global map for introgressed structural variation and selection in humans

When ancient humans interbred with Neanderthals and Denisovans, they inherited not just single-nucleotide variants but also larger structural variants (SVs) — deletions, insertions, and rearrangements of 50 base pairs or more. These SVs have been difficult to detect until now. Researchers combined four newly assembled haploid genomes from Papua New Guinea (PNG) with 94 published diverse-ancestry assemblies to build a comprehensive map of introgressed SVs. Nearly half of these variants fall within genes, including regions linked to genomic disorders, and PNG genomes carry the highest burden. Strikingly, 11 centromeres appear to derive from archaic hominins, opening new questions about centromere diversity. Genotyping across over 1,300 samples revealed 16 SVs showing signs of positive selection, many near immune-related genes, predominantly in PNG populations. The findings suggest archaic structural variation contributed to reproductive fitness, reinforcing the view that introgression was a significant driver of human adaptive evolution.

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Global density and biomass of arbuscular mycorrhizal fungal networks

Arbuscular mycorrhizal fungi partner with roughly 70% of plant species, threading soil with vast networks of hyphae that shuttle nutrients to plants in exchange for carbon. Despite their ecological importance, no one had quantified just how much fungal infrastructure exists globally. Researchers compiled data from over 16,000 soil cores spanning 322 studies and nine biomes, then built machine-learning models to predict hyphal densities worldwide. Robotic imaging of more than 300,000 individual hyphae helped calibrate a biomass conversion model. The resulting estimates are striking: topsoils worldwide harbor roughly 1.1 × 10¹⁷ kilometers of living hyphae, with a total mass around 300 megatons — four to six times the combined biomass of all humans. The work also pinpoints biomes where sampling remains sparse, flagging priorities for future fieldwork. These figures underscore how fundamentally fungal networks shape global carbon and nutrient cycling.

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Unveiling the complexity of post-Roman polity formation in Pannonia using ancient DNA

Using ancient DNA from burial sites in what is now western Hungary, researchers examined how political and social structures changed as Roman authority collapsed between the 4th and 9th centuries CE. Analyzing genetic material from two Roman-era sites and five post-Roman sites — totaling over 300 individuals — they found a marked increase in Northern European ancestry, indicating substantial population immigration into the region. Despite the post-Roman communities sharing similar genetic backgrounds, material goods, and burial customs, they differed notably in how biological kinship shaped their social organization. Some groups structured their hierarchies around family ties more than others. These findings reveal that even superficially similar post-Roman communities were organizationally distinct at a local level, demonstrating that the fragmentation of Roman power produced complex, regionally varied outcomes rather than a uniform cultural or demographic replacement.

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Patterns of brain-wide associations reflect socioeconomics

Researchers analyzed how children's brains relate to a broad range of environmental and behavioral factors by mapping 649 variables onto brain imaging data. Socioeconomic status (SES) produced the strongest associations across the brain, particularly in motor and sensory regions rather than cognitive ones. Strikingly, this same spatial pattern appeared across many other variables, including IQ, suggesting a single common brain signature underlies most associations. When SES was statistically controlled, brain-IQ associations weakened substantially and the motor-sensory pattern disappeared. Brain-IQ models trained on higher-SES children also failed to generalize to lower-SES groups. The findings suggest that much of what brain-wide association studies attribute to specific behavioral or cognitive variables may actually reflect socioeconomic differences, potentially mediated by SES-linked factors like sleep deprivation and stress. This has important implications for how neuroscientists interpret and report brain-behavior relationships in developmental populations.

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Long-term isolation and archaic introgression shape functional genetic variation in Near Oceania

Populations of Near Oceania (Papua New Guinea and surrounding islands) remain poorly represented in large-scale genomic studies despite their remarkable diversity. Researchers sequenced 177 high-coverage genomes from these populations and compared them with over 1,200 genomes from around the world. The analysis revealed prolonged isolation and severe population bottlenecks within and between islands. By reconstructing nearly 1.9 billion base pairs of archaic hominin sequence—including over 830 million from Denisovan lineages—the team identified contributions from three distinct Denisovan-like groups. One notable signal of adaptive introgression centered on TRPS1, a skeletal development gene also selected in central African hunter-gatherers and Ecuadorian highland populations. Using a massively parallel reporter assay to test regulatory function at scale, the researchers identified over 3,000 introgressed variants that influence gene expression, with a notable concentration in the interferon-γ immune signaling pathway, suggesting archaic DNA has had lasting functional consequences for immunity in these populations.

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