Looking Old
Inference of human pigmentation from ancient DNA by genotype likelihoods
Silvia Perretti et al.
Proceedings of the National Academy of Sciences, 22 July 2025
Abstract:
Light eyes, hair, and skins probably evolved several times as Homo sapiens dispersed from Africa. In areas with lower UV radiation, light pigmentation alleles increased in frequency because of their adaptive advantage and of other contingent factors such as migration and drift. However, the tempo and mode of their spread is not known. Phenotypic inference from ancient DNA is complicated, both because these traits are polygenic and because of low sequence depth. We evaluated the effects of the latter by randomly removing reads in three high-coverage ancient samples, the Paleolithic Ust’-Ishim from Russia, the Mesolithic SF12 from Sweden, and the Neolithic I5077 from current Croatia. We could thus compare three approaches to pigmentation inference, concluding that for suboptimal levels of coverage (<8×), a probabilistic method estimating genotype likelihoods leads to the most robust predictions. We then applied that protocol to 348 ancient genomes from Eurasia, describing how skin, eye, and hair color evolved over the past 45,000 y. The shift toward lighter pigmentations turned out to be all but linear in time and place, and slower than expected, with half of the individuals showing dark or intermediate skin colors well into the Bronze and Iron ages. We also observed a peak of light eye pigmentation in Mesolithic times, and an accelerated change during the spread of Neolithic farmers over Western Eurasia, although localized processes of gene flow and admixture, or lack thereof, also played a significant role.
Contextualizing ancient texts with generative neural networks
Yannis Assael et al.
Nature, forthcoming
Abstract:
Human history is born in writing. Inscriptions are among the earliest written forms, and offer direct insights into the thought, language and history of ancient civilizations. Historians capture these insights by identifying parallels -- inscriptions with shared phrasing, function or cultural setting -- to enable the contextualization of texts within broader historical frameworks, and perform key tasks such as restoration and geographical or chronological attribution. However, current digital methods are restricted to literal matches and narrow historical scopes. Here we introduce Aeneas, a generative neural network for contextualizing ancient texts. Aeneas retrieves textual and contextual parallels, leverages visual inputs, handles arbitrary-length text restoration, and advances the state of the art in key tasks. To evaluate its impact, we conduct a large study with historians using outputs from Aeneas as research starting points. The historians find the parallels retrieved by Aeneas to be useful research starting points in 90% of cases, improving their confidence in key tasks by 44%. Restoration and geographical attribution tasks yielded superior results when historians were paired with Aeneas, outperforming both humans and artificial intelligence alone. For dating, Aeneas achieved a 13-year distance from ground-truth ranges. We demonstrate Aeneas’ contribution to historical workflows through analysis of key traits in the renowned Roman inscription Res Gestae Divi Augusti, showing how integrating science and humanities can create transformative tools to assist historians and advance our understanding of the past.
From ritual spaces to monumental expressions: Rethinking East Polynesian ritual practices
Paul Wallin & Helene Martinsson-Wallin
Antiquity, forthcoming
Abstract:
As with the peopling of the Pacific Islands, the monumental ritual architecture of East Polynesia is presumed to have spread from West Polynesia. By re-examining the wealth of absolute dates available from ritual contexts across these diverse islands, the authors challenge this generalisation in Polynesian ideological materialisation, identifying three phases of development. They argue that initial west-to-east migration spread the concept of ritual spaces marked by stone uprights c. AD 1000–1300, then the formalisation of monuments diffused in the opposite direction c. AD 1300–1600, before megastructures emerged from localised hierarchisation, perhaps earliest on Rapa Nui c. AD 1350–1500.
Environmental variability shapes the representational format of cultural learning
Xavier Roberts-Gaal, Marija Bolic & Fiery Cushman
Proceedings of the National Academy of Sciences, 15 July 2025
Abstract:
Cumulative culture requires learning mechanisms that are both efficient and flexible in the face of environmental change. We examine models of this learning mechanism that emphasize teaching what to do (causally opaque procedures) and those that foreground what to aim for and why (goals and causal reasoning). Learning procedures is cheap but inflexible; learning goals is more flexible to changing circumstance, but requires expensive individual learning about how to achieve them. In an iterated learning experiment, we demonstrate that cultural learning adapts in precisely this way: Microcultures more often instruct future generations to follow procedures when the world is stable, but they tend to share information about valuable outcomes and causal relations when the world is variable.
Summer warmth between 15,500 and 15,000 years ago enabled human repopulation of the northwest European margin
Ian Matthews et al.
Nature Ecology & Evolution, July 2025, Pages 1179-1192
Abstract:
High-magnitude decadal to centennial-scale abrupt changes in climate had a transformative effect on many past human populations. However, our understanding of these human/climate relationships is limited because robust tests of these linkages require region-specific quantified palaeoclimatic data with sufficient chronological precision to permit comparisons to the archaeological record. Here we present new high-resolution palaeoclimatic data and combine these with radiocarbon inventories of archaeological and faunal material, to test the relationship between abrupt warming and the ability of humans to rapidly repopulate the northwest margins of Europe (>50° N and encompassing the area of Britain, Ireland, the surrounding islands and the North Sea basin) after regional abandonment during the Last Glacial Maximum. We address the timing of this process and the relevance of the abrupt climate changes recorded in the Greenland ice cores. We use the IntCal20 radiocarbon calibration curve to show that the earliest human repopulation in this region occurred up to 500 years before the climate of Greenland warmed. However, our analyses show that parts of the northwest European margin had already experienced substantial summer warming by this time, probably driven by changes of sea-ice area in the eastern North Atlantic. The associated warming influenced the distribution of key hunter-gatherer prey species such as reindeer, which were a key resource for humans. Accordingly, this study highlights asynchrony in seasonal warming across the North Atlantic region during the last deglaciation and shows that this asynchrony permitted human exploitation of northwest European margin paraglacial landscapes by ~15,200 years before the present.