Wild Times
Drought, Population Pressure, and Inequality Drive Intergroup Conflict in the Precontact North American Southwest
Weston McCool et al.
American Antiquity, forthcoming
Abstract:
To anticipate relationships between future climate change and societal violence, we need theory to establish causal links and case studies to estimate interactions between driving forces. Here, we couple evolutionary ecology with a machine-learning statistical approach to investigate the long-term effects of climate change, population growth, and inequality on intergroup conflict among farmers in the North American Southwest. Through field investigations, we generate a new archaeological dataset of farming settlements in the Bears Ears National Monument spanning 1,300 years (0 to AD 1300) to evaluate the direct and interactive effects of precipitation, temperature, climate shocks, demography, and wealth inequality on habitation site defensibility — our proxy for intergroup conflict. We find that conflict peaked during dry, warm intervals when population density and inequality were highest. Results support our theoretical predictions and suggest cascading effects, whereby xeric conditions favored population aggregation into an increasingly small, heterogenous area, which increased resource stress and inequality and promoted intergroup conflict over limited productive patches. This dynamic likely initiated feedback loops, whereby conflict exacerbated shortfalls and fostered mistrust, which drove further aggregation and competition. Results reveal complex interactions among socioclimatological conditions, all of which may have contributed to regional depopulation during the thirteenth century AD.
Climate-driven changes in Mediterranean grain trade mitigated famine but introduced the Black Death to medieval Europe
Martin Bauch & Ulf Büntgen
Communications Earth & Environment, December 2025
Abstract:
The first wave of the second plague pandemic, the Black Death, claimed much of Europe’s human population in just a few years after 1347 CE. While it is accepted that the causative bacterium Yersinia pestis originated from wildlife rodent populations in central Asia and reached Europe via the Black Sea region, reasons for the timing, spread and virulence of the onset of the Black Death are still debated. Here, we argue that a post-volcanic climate downturn and trans-Mediterranean famine from 1345–1347 CE forced the Italian maritime republics of Venice, Genoa and Pisa to activate their well-established supply network and import grain from the Mongols of the Golden Horde around the Sea of Azov in 1347 CE. This climate-driven change in long-distance grain trade not only prevented large parts of Italy from starvation but also introduced the plague bacterium to Mediterranean harbours and fueled its rapid dispersal across much of Europe.
The first preserved nasal cavity in the human fossil record: The Neanderthal from Altamura
Costantino Buzi et al.
Proceedings of the National Academy of Sciences, 2 December 2025
Abstract:
The nose of Neanderthals and its possible adaptation to harsh climatic conditions is a longstanding matter of debate in paleoanthropology. Here, we present and describe the complete inner nasal structures of the early Neanderthal skeleton from Altamura, southern Italy. It represents evidence hitherto unavailable, both for this species and the human fossil record in general, and sheds light on the possible influence of respiratory adaptations on the characteristic Neanderthal facial morphology. Part of the debate has revolved around inner nasal traits proposed as unique adaptations (autapomorphies) of the species Homo neanderthalensis in relation to cold climate, specifically: a vertically oriented medial projection and a medial swelling on the nasal cavity wall alongside the lack of an ossified roof over the lacrimal groove. The lack of complete anatomy in the Neanderthal fossil record further livened the discussion regarding their occurrence. With the description and analysis of this unique finding, we can rule out the existence of such features. In addition, our observations corroborate the hypothesis that the characteristic midfacial morphology of H. neanderthalensis (i.e., the midfacial prognathism) is the result of a combination of factors and not a direct result of respiratory adaptations in the upper airways. Finally, our data provide an enhanced perspective for modeling Neanderthal respiratory performances.
Landscape-wide cosmogram built by the early community of Aguada Fénix in southeastern Mesoamerica
Takeshi Inomata et al.
Science Advances, November 2025
Abstract:
There is growing recognition that societies without prominent hierarchies could build large constructions. Scholars are debating what motivated many people to participate in these construction projects. We investigated the site of Aguada Fénix, Mexico, which features the oldest and largest monumental architecture in the Maya area. Using light detection and ranging (LiDAR) and excavations, we documented a site plan composed of nested cross forms built between 1050 and 700 BCE. Its center was marked by a large cruciform cache containing the earliest known directional color symbols in Mesoamerica. The overall pattern consisted of 9- and 7.5-kilometer-long axes delineated by canals and corridors. The builders constructed canals, measuring up to 35 meters wide and 5 meters deep, and a dam to supply them with lake water. Although the canals appear unfinished, this site plan exceeded or rivaled the extents of later Mesoamerican cities. Aguada Fénix was probably designed as a cosmogram, which likely attracted people from a broad area.
Homo sapiens-specific evolution unveiled by ancient southern African genomes
Mattias Jakobsson et al.
Nature, forthcoming
Abstract:
Homo sapiens evolved hundreds of thousands of years ago in Africa, later spreading across the globe, but the early evolutionary process is debated. Here we present whole-genome sequencing data for 28 ancient southern African individuals, including six individuals with 25× to 7.2× genome coverage, dated to between 10,200 and 150 calibrated years before present (cal. BP). All ancient southern Africans dated to more than 1,400 cal. BP show a genetic make-up that is outside the range of genetic variation in modern-day humans (including southern African Khoe-San people, although some retain up to 80% ancient southern African ancestry), manifesting in a large fraction of Homo sapiens-specific variants that are unique to ancient southern Africans. Homo sapiens-specific variants at amino acid-altering sites fixed for all humans — which are likely to have evolved rapidly on the Homo sapiens branch — were enriched for genes associated with kidney function. Some Homo sapiens-specific variants fixed in ancient southern Africans — which are likely to have adapted rapidly on the southern African branch — were enriched for genes associated with protection against ultraviolet light. The ancient southern Africans show little spatiotemporal stratification for 9,000 years, consistent with a large, stable Holocene population transcending archaeological phases. While southern Africa served as a long-standing geographical refugium, there is outward gene flow over 8,000 years ago; however, inward gene flow manifests only after around 1,400 years ago. The ancient genomes reported here are therefore key to the evolution of Homo sapiens, and are important for advancing our understanding of human genomic variation.
Reassessing the role of Polynesian rats (Rattus exulans) in Rapa Nui (Easter Island) deforestation: Faunal evidence and ecological modeling
Terry Hunt & Carl Lipo
Journal of Archaeological Science, December 2025
Abstract:
The role of introduced Polynesian rats (Rattus exulans) in the deforestation of Rapa Nui remains a contentious issue. Several critics, including Mieth and Bork (2010), argue that rats played a negligible role compared to human impacts. We address the role of rats through three lines of evidence: (1) a response to rats-are-negligible arguments, including problematic continental analogies and misunderstandings of seed predation impacts; (2) analysis of rat remains from Anakena excavations (1986–2005) showing that rats decreased over time, contradicting claims they served as a “fallback food” following resource depletion; and (3) ecological modeling demonstrating that introduced rats could reach populations of 11.2 million within 47 years, with 95 % seed predation sufficient to prevent palm regeneration. Our integrated evidence supports rats as a keystone invasive species that, through synergistic interactions with human forest clearing, drove one of the most complete ecological transformations documented in human history. These findings challenge narratives of simple anthropogenic “ecocide” and highlight the critical role of invasive species in island environmental change.