Long Live Humanity
Violence trends in the ancient Middle East between 12,000 and 400 BCE
Joerg Baten, Giacomo Benati & Arkadiusz Sołtysiak
Nature Human Behaviour, forthcoming
Abstract:
How did interpersonal violence develop in early human societies? Given that homicide records are only available for the more recent period, much of human history remains outside our purview. In this paper, we study violence trends in the very long run by exploiting a new dataset on cranial trauma and weapon-related wounds from skeletons excavated across the Middle East, spanning the pre-Classical period (around 12,000–400 BCE). The dataset includes more than 3,500 individuals. We find evidence that interpersonal violence peaked during the Chalcolithic period (around 4,500–3,300 BCE). It then steadily declined during the Early and Middle Bronze Ages (around 3,300–1,500 BCE) and increased again between the Late Bronze and the Iron Age (1,500–400 BCE). By documenting variations in violence patterns across a vast temporal and geographical scale in an incredibly rich historical setting, we broaden perspectives on the early history of human conflict.
Aggressive Mimicry and the Evolution of the Human Cognitive Niche
Cody Moser et al.
Human Nature, September 2023, Pages 456–475
Abstract:
The evolutionary origins of deception and its functional role in our species is a major focus of research in the science of human origins. Several hypotheses have been proposed for its evolution, often packaged under either the Social Brain Hypothesis, which emphasizes the role that the evolution of our social systems may have played in scaffolding our cognitive traits, and the Foraging Brain Hypothesis, which emphasizes how changes in the human dietary niche were met with subsequent changes in cognition to facilitate foraging of difficult-to-acquire foods. Despite substantive overlap, these hypotheses are often presented as competing schools of thought, and there have been few explicitly proposed theoretical links unifying the two. Utilizing cross-cultural data gathered from the Human Relations Area Files (HRAF), we identify numerous (n = 357) examples of the application of deception toward prey across 145 cultures. By comparing similar behaviors in nonhuman animals that utilize a hunting strategy known as aggressive mimicry, we suggest a potential pathway through which the evolution of deception may have taken place. Rather than deception evolving as a tactic for deceiving conspecifics, we suggest social applications of deception in humans could have evolved from an original context of directing these behaviors toward prey. We discuss this framework with regard to the evolution of other mental traits, including language, Theory of Mind, and empathy.
Modeling mate choice in a small-scale community: Applying couple simulation in the U.S. and Conambo, Ecuador
Daniel Conroy-Beam et al.
Evolution and Human Behavior, forthcoming
Abstract:
The near totality of human mate choice research occurs in large-scale, urban, industrial populations. It is unclear to what extent lessons learned from such populations reflect generalizable features of human mating psychology as opposed to localized responses to the demands of these historically unusual environments. Here, we use couple simulation, an agent-based modeling technique, to compare models of mate choice across both a U.S. sample (n = 1678) and a sample of k = 15 couples from Conambo, Ecuador -- a relatively remote community of horticultural-foragers in the Ecuadorian Amazon. The Conambo sample provides a unique opportunity to evaluate models of mate choice in that (1) this sample represents approximately 50% of the households within this community and (2) all of the participants in this sample are acquainted with one another. Participants in Conambo completed a ranking task in which each participant ranked each opposite-sex adult in the community in terms of their quality as a spouse. We used these rankings to simulate the mating market in Conambo under alternative models of mate choice. We find that these models are able to reproduce Conambo marriages at a high degree of accuracy and perform comparably across both the Conambo sample and U.S. samples. Specifically, the resource allocation model performs best in reproducing mate choices in both the U.S. and Conambo samples. These results suggest that at least some aspects of human mating psychology generalize across both large-scale industrialized and small-scale populations.
Early Homo erectus lived at high altitudes and produced both Oldowan and Acheulean tools
Margherita Mussi et al.
Science, forthcoming
Abstract:
In Africa, the scarcity of hominin remains found in direct association with stone tools has hindered attempts to link Homo habilis and Homo erectus with particular lithic industries. The infant mandible discovered in level E at Garba IV (Melka Kunture) on the highlands of Ethiopia is critical to this issue due to its direct association with an Oldowan lithic industry. Here, we use synchrotron imaging to examine the internal morphology of the unerupted permanent dentition and confirm its identification as Homo erectus. Additionally, we utilize new palaeomagnetic ages to show that (i) the mandible in level E is ca. 2 million-years-old, and represents one of the earliest Homo erectus fossils, and (ii) that overlying level D, ca. 1.95 million-years-old, contains the earliest known Acheulean assemblage.
Human Amygdala Volumetric Patterns Convergently Evolved in Cooperatively Breeding and Domesticated Species
Paola Cerrito & Judith Burkart
Human Nature, September 2023, Pages 501–511
Abstract:
The amygdala is a hub in brain networks that supports social life and fear processing. Compared with other apes, humans have a relatively larger lateral nucleus of the amygdala, which is consistent with both the self-domestication and the cooperative breeding hypotheses of human evolution. Here, we take a comparative approach to the evolutionary origin of the relatively larger lateral amygdala nucleus in humans. We carry out phylogenetic analysis on a sample of 17 mammalian species for which we acquired single amygdala nuclei volumetric data. Our results indicate that there has been convergent evolution toward larger lateral amygdala nuclei in both domesticated and cooperatively breeding mammals. These results suggest that changes in processing fearful stimuli to reduce fear-induced aggression, which are necessary for domesticated and cooperatively breeding species alike, tap into the same neurobiological proximate mechanism. However, humans show changes not only in processing fearful stimuli but also in proactive prosociality. Since cooperative breeding, but not domestication, is also associated with increased proactive prosociality, a prominent role of the former during human evolution is more parsimonious, whereas self-domestication may have been involved as an additional stepping stone.
Formation processes, fire use, and patterns of human occupation across the Middle Palaeolithic (MIS 5a-5b) of Gruta da Oliveira (Almonda karst system, Torres Novas, Portugal)
Diego Angelucci, Mariana Nabais & João Zilhão
PLoS ONE, October 2023
Abstract:
Gruta da Oliveira features a c. 13 m-thick infilling that includes a c. 6.5 m-thick archaeological deposit (the “Middle Palaeolithic sequence” complex), which Bayesian modelling of available dating results places in MIS 5a (layers 7–14) and MIS 5b (layers 15–25), c. 71,000–93,000 years ago. The accumulation primarily consists of sediment washed in from the slope through gravitational processes and surface dynamics. The coarse fraction derives from weathering of the cave’s limestone bedrock. Tectonic activity and structural instability caused the erosional retreat of the scarp face, explaining the large, roof-collapsed rock masses found through the stratification. The changes in deposition and diagenesis observed across the archaeological sequence are minor and primarily controlled by local factors and the impact of humans and other biological agents. Pulses of stadial accumulation -- reflected in the composition of the assemblages of hunted ungulates, mostly open-country and rocky terrain taxa (rhino, horse, ibex) -- alternate with interstadial hiatuses -- during which carbonate crusts and flowstone formed. Humans were active at the cave throughout, but occupation was intermittent, which allowed for limited usage by carnivores when people visited less frequently. During the accumulation of layers 15–25 (c. 85,000–93,000 years ago), the carnivore guild was dominated by wolf and lion, while brown bear and lynx predominate in layers 7–14 (c. 71,000–78,000 years ago). In the excavated areas, conditions for residential use were optimal during the accumulation of layers 20–22 (c. 90,000–92,000 years ago) and 14 (c. 76,000–78,000 years ago), which yielded dense, hearth-focused scatters of stone tools and burnt bones. The latter are ubiquitous, adding to the growing body of evidence that Middle Palaeolithic Neandertals used fire in regular, consistent manner. The patterns of site usage revealed at Gruta da Oliveira are no different from those observed 50,000 years later in comparable early Upper Palaeolithic and Solutrean cave sites of central Portugal.