Foraging Groups Research Articles

A pre-Campanian Ignimbrite techno-cultural shift in the Aurignacian sequence of Grotta di Castelcivita, southern Italy

The Aurignacian is the first European technocomplex assigned to Homo sapiens recognized across a wide geographic extent. Although archaeologists have identified marked chrono-cultural shifts within the Aurignacian mostly by examining the techno-typological variations of stone and osseous tools, unraveling the underlying processes driving these changes remains a significant scientific challenge. Scholars have, for instance, hypothesized that the Campanian Ignimbrite (CI) super-eruption and the climatic deterioration associated with the onset of Heinrich Event 4 had a substantial impact on European foraging groups. The technological shift from the Protoaurignacian to the Early Aurignacian is regarded as an archaeological manifestation of adaptation to changing environments. However, some of the most crucial regions and stratigraphic sequences for testing these scenarios have been overlooked. In this study, we delve into the high-resolution stratigraphic sequence of Grotta di Castelcivita in southern Italy. Here, the Uluzzian is followed by three Aurignacian layers, sealed by the eruptive units of the CI. Employing a comprehensive range of quantitative methods—encompassing attribute analysis, 3D model analysis, and geometric morphometrics—we demonstrate that the key technological feature commonly associated with the Early Aurignacian developed well before the deposition of the CI tephra. Our study provides thus the first direct evidence that the volcanic super-eruption played no role in this cultural process. Furthermore, we show that local paleo-environmental proxies do not correlate with the identified patterns of cultural continuity and discontinuity. Consequently, we propose alternative research paths to explore the role of demography and regional trajectories in the development of the Upper Paleolithic.

Dietary tryptophan affects group behavior in a social bird

Abstract The amino acid tryptophan (Trp) is a precursor of the neurotransmitter serotonin. Trp supplementation or other forms of serotonergic enhancement generally promote pro-social behavior, decreasing aggression, and also feeding in different animals. However, past research has been conducted in confined spaces, and there is little work in naturalistic conditions where animals move and associate more freely. We gave a Trp-enriched diet to a free-flying flock of common waxbills (Estrilda astrild) in semi-natural conditions and monitored group foraging, aggressions during feeding, and the social network. Contrary to expectations, aggressiveness and feeding increased during Trp supplementation. Consistent with the prediction of increased social associations, foraging groups became larger, and individuals joined more foraging groups, but these changes appear driven by increased appetite during Trp treatment. Also, the mean strength of associations in the social network did not change. Overall, Trp supplementation affected group behavior in this free-flying flock, but mostly in directions unanticipated based on research conducted in small spaces. To harmonize our results with those found in small confined spaces, we hypothesize that free-flying birds have energetic requirements not experienced in lab-housed individuals, which may impact social behavior and responses to Trp.

Effects of foraging mode and group pattern on vigilance behavior in water birds: a case study of mallard and black-winged stilt

Vigilance behavior is affected by many factors including foraging mode and group pattern which we attempted to understand through a case study of mallard Anas platyrhynchos and black-winged stilt Himantopus himantopus in the Hengshui Lake National Nature Reserve, China. Mallard, a swimming bird, forages in irregular and loose circular groups in open water and its foraging mode (with its head underwater looking for food) does not allow for simultaneous monitoring of potential threats above the water surface, which is why its foraging is called “blind period of foraging”. In contrast, black-winged stilt is a wading bird and forages along riversides in long linear foraging groups. Its long beak, neck and legs enable it to scan around while foraging without any obviously blind period. We used the focal sampling method and measured vigilance behavior by the time spent vigilant, vigilance frequency, average duration of vigilance, alert distance and flee distance for the two species. We predicted higher levels of vigilance and longer alert and flee distance in mallard with long blind periods of foraging. Our results indicated significant differences (p

Reconsidering the link between past material culture and cognition in light of contemporary hunter-gatherer material use.

Many have interpreted symbolic material culture in the deep past as evidencing the origins sophisticated, modern cognition. Scholars from across the behavioural and cognitive sciences, including linguists, psychologists, philosophers, neuroscientists, primatologists, archaeologists and paleoanthropologists have used such artefacts to assess the capacities of extinct human species, and to set benchmarks, milestones or otherwise chart the course of human cognitive evolution. To better calibrate our expectations, the present paper instead explores the material culture of three contemporary African forager groups. Results show that, while these groups are unequivocally behaviourally modern, they would leave scant long-lasting evidence of symbolic behaviour. Artefact-sets are typically small, perhaps as consequence of residential mobility. When excluding traded materials, few artefacts have components with moderate-strong taphonomic signatures. Present analyses show that artefact function influences preservation probability, such that utilitarian tools for the processing of materials and the preparation of food are disproportionately likely to contain archaeologically traceable components. There are substantial differences in material-use between populations, which create important population-level variation preservation probability independent of cognitive differences. I discuss the factors - cultural, ecological and practical - that influence material choice. In so doing, I highlight the difficulties of using past material culture as an evolutionary or cognitive yardstick.

Coupled information networks drive honeybee (Apis mellifera) collective foraging.

Collective behaviour by eusocial insect colonies is typically achieved through multiple communication networks that produce complex behaviour at the group level but often appear to provide redundant or even competing information. A classic example occurs in honeybee (Apis mellifera) colonies, where both the dance communication system and robust scent-based mechanisms contribute to the allocation of a colony's workforce by regulating the flow of experienced foragers among known food sources. Here we analysed social connectivity patterns during the reactivation of experienced foragers to familiar feeding sites to show that these social information pathways are not simply multiple means to achieve the same end but intersect to play complementary roles in guiding forager behaviour. Using artificial feeding stations, we mimicked a natural scenario in which two forager groups were simultaneously collecting from distinct patches containing different flowering species. We then observed the reactivation of these groups at their familiar feeding sites after interrupting their foraging. Social network analysis revealed that temporarily unemployed individuals interacted more often and for longer with foragers that advertised a familiar versus unfamiliar foraging site. Due to such resource-based assortative mixing, network-based diffusion analysis estimated that reactivation events primarily resulted from interactions among bees that had been trained to the same feeding station and less so from different-feeder interactions. Both scent- and dance-based interactions strongly contributed to reactivation decisions. However, each bout of dance-following had an especially strong effect on a follower's likelihood of reactivation, particularly when dances indicated locations familiar to followers. Our findings illustrate how honeybee foragers can alter their social connectivity in ways that are likely to enhance collective outcomes by enabling foragers to rapidly access up-to-date information about familiar foraging sites. In addition, our results highlight how reliance on multiple communication mechanisms enables social insect workers to utilise flexible information-use strategies that are robust to variation in the availability of social information.

An ethnoarchaeological comparison of observed butchery actions to bone surface modifications of the Dobe !Kung San

ABSTRACT The Dobe !Kung were a group of foragers living in northern Botswana in the Kalahari Desert. In the second half of the twentieth century, their butchery actions on animal prey were recorded (1968–1975) and their abandoned camps from 1944–1976 were excavated to retrieve faunal remains from butchered prey animals. Here we test the hypothesis that bone surface modifications on these excavated faunal remains accurately reflect these butchery observations. We find that despite a few exceptions, the observed bone surface modifications follow the expectations derived from observations of butchery of different sized animals. This supports the idea that past butchery actions, based on the location and presence of bone surface modifications on modern bones, can be confidently linked to past butchery behaviours. We also suggest that bone surface modifications can provide information about past hunter-gatherer processing behaviours, cooking styles, and use of hides.

Evidence for an emotional adaptive function of dreams: a cross-cultural study

The function of dreams is a longstanding scientific research question. Simulation theories of dream function, which are based on the premise that dreams represent evolutionary past selective pressures and fitness improvement through modified states of consciousness, have yet to be tested in cross-cultural populations that include small-scale forager societies. Here, we analyze dream content with cross-cultural comparisons between the BaYaka (Rep. of Congo) and Hadza (Tanzania) foraging groups and Global North populations, to test the hypothesis that dreams in forager groups serve a more effective emotion regulation function due to their strong social norms and high interpersonal support. Using a linear mixed effects model we analyzed 896 dreams from 234 individuals across these populations, recorded using dream diaries. Dream texts were processed into four psychosocial constructs using the Linguistic Inquiry and Word Count (LIWC-22) dictionary. The BaYaka displayed greater community-oriented dream content. Both the BaYaka and Hadza exhibited heightened threat dream content, while, at the same time, the Hadza demonstrated low negative emotions in their dreams. The Global North Nightmare Disorder group had increased negative emotion content, and the Canadian student sample during the COVID-19 pandemic displayed the highest anxiety dream content. In conclusion, this study supports the notion that dreams in non-clinical populations can effectively regulate emotions by linking potential threats with non-fearful contexts, reducing anxiety and negative emotions through emotional release or catharsis. Overall, this work contributes to our understanding of the evolutionary significance of this altered state of consciousness.

Killer whales at northern Patagonia, Argentina: Evidence of different foraging groups from stable isotopes

AbstractKiller whales (Orcinus orca) are highly mobile, large marine apex predators that inhabit all oceans. Despite being the most conspicuous top predator, little is known about their ecology along Patagonia, Argentina. Here, we used carbon (δ13C) and nitrogen (δ15N) isotope analysis of bone and dentine collagen from killer whales (n = 13) stranded in northern Patagonia during the period 1970–2014 to assess their trophic ecology. A model‐based clustering analysis identified three distinct groups related with three large marine ecosystems: the Patagonia (P), Subtropical (ST), and Antarctica (A) groups. Group P (n = 8) is characterized by individuals with high δ13C and δ15N values fitting within the isotopic ratios observed over the Patagonian shelf. Group ST (n = 3) is composed of individuals with high δ13C and low δ15N values, similar to those reported for conspecifics in southern Brazil. Group A (n = 2) is composed of individuals with low δ13C and δ15N values, typical from high latitude areas like sub‐Antarctic/Antarctic waters. The finding of different killer whales' isotopic groups over the Patagonian shelf suggests the existence of individuals or groups exploiting different habitats. Our results expand the limited ecological knowledge for the species while presenting the basis to infer more complex ecological hypotheses.

The human-initiated model of wolf domestication - An expansion based on human-dingo relations in Aboriginal Australia.

The historically known relationship of interspecies companionship between Aboriginal foraging communities in Australia and free-ranging dingoes provides a model for understanding the human-canid relations that gave rise to the first domesticated dogs. Here, we propose that a broadly similar relationship might have developed early in time between wild-living wolves and mobile groups of foragers in Late Pleistocene Eurasia, with hunter-gatherers routinely raiding wild wolf dens for pre-weaned pups, which were socialized to humans and kept in camp as tamed companions ("pets"). We outline a model in which captive wolf pups that reverted to the wild to breed when they were sexually mature established their territories in the vicinity of foraging communities - in a "liminal" ecological zone between humans and truly wild-living wolves. Many (or most) of the wolf pups humans took from the wilderness to rear in camp may have derived from these liminal dens where the breeding pairs had been under indirect human selection for tameness over many generations. This highlights the importance of the large seasonal hunting/aggregation camps associated with mammoth kill-sites in Gravettian/Epigravettian central Europe. Large numbers of foragers gathered regularly at these locations during the wild wolf birthing season. We infer that if a pattern of this kind occurred over long periods of time then there might have been a pronounced effect on genetic variation in free-ranging wolves that denned and whelped in the liminal zones in the vicinity of these human seasonal aggregation sites. The argument is not that wolves were domesticated in central Europe. Rather, it is this pattern of hunter-gatherers who caught and reared wild wolf pups gathering seasonally in large numbers that might have been the catalyst for the early changes leading to the first domesticated dogs - whether in western Eurasia or further afield.

Human consumption of large herbivore digesta and its implications for foraging theory.

Vegetal matter undergoing digestion in herbivores' stomachs and intestines, digesta, can be an important source of dietary carbohydrates for human foragers. Digesta significantly increases large herbivores' total caloric yield and broadens their nutritional profile to include three key macronutrients (protein, fat, and carbohydrates) in amounts sufficient to sustain small foraging groups for multiple days without supplementation. Ethnographic reports of routine digesta consumption are limited to high latitudes, but the practice may have had a wider distribution prehistorically. Including this underappreciated resource in our foraging hypotheses and models can substantively change their predictions. Assessing the explanatory power of kilocalorie-centered models relative to ones that attend to humans' other nutritional requirements can help us better address major questions in evolutionary anthropology. This paper explores the foraging implications of digesta in two contexts-sex-divided subsistence labor and archaeologically observed increases in plant use and sedentism-using estimates of available protein and carbohydrates in the native tissues and digesta, respectively, of a large ruminant herbivore (Bison bison).

The Globular Amphora Culture in the Eastern Baltic: New Discoveries

Abstract Until now, Šventoji in northwest Lithuania was considered the most northern site of the Neolithic Globular Amphora Culture (hereafter GAC; ca. 3400–2500 cal BC) in Europe. Recently, however, ceramics typologically resembling GAC ware were identified among the materials from the multi-period sites of Abora 1 and Iča in Latvia and further to the north from Tamula in southeast Estonia. Here we present the multi-disciplinary analyses of these ceramics, including their morphology, function and chronology, to ascertain whether they could represent sporadic migrations of GAC groups into the region or exchange and increasing social contacts with the indigenous hunter-gatherers during the period from ca. 3000–2600 cal BC. Overall, our results align with previous studies showing that GAC groups in the Eastern Baltic possibly reorientated their economy from animal husbandry towards fishing, as recently evidenced by the composition of zooarchaeological assemblages, and the organic residue analysis of ceramic vessels, which markedly differ from the GAC communities of Central Europe. Indeed, in several coastal and southern regions of Lithuania, it would appear that some GAC migrants replaced the indigenous Subneolithic forager groups, whilst in other areas, they had little to no impact on the local cultural and economic development.

Pastoralism, hunting, and coexistence: Domesticated and wild bovids in Neolithic Sudan

AbstractThe interactions between mobile pastoralists and semi‐sedentary Nilotic foraging groups in the Middle Nile Valley had long‐term implications for the development of social complexity as seen in the ancient African kingdom of Kerma. This study presents the results of the zooarcheological analysis of animal remains from two sites in the 4th cataract of the Nile valley, El Ginefab and Shemkhiya, and compares findings to other published sites in the region during a period of significant climatic change. Results indicate that the communities living at Shemkhiya and El Ginefab differed in terms of their meat preferences and their primary modes of bovid acquisition, and that pastoralist practices changed at El Ginefab through time. Hunting remained an important feature of subsistence practices, and regional comparisons indicate that the acquisition of wild bovids did not disappear with incorporation of domesticated livestock; however, pastoralists limited their hunting practices to smaller wild bovids in contrast to neighboring forager populations. A clear chronological overlap is documented between communities reliant on pastoralism and those reliant on hunting as a subsistence practice for several millennia. This highlights the need to more explicitly characterize and understand the dynamics of coexistence for the spread and establishment of pastoralism regionally, as well as how social ties, subsistence practices, and land use practices overlapped during periods of critical environmental changes and their implications for emerging social complexity.

Impact of water level on spring bird assemblages in a natural river valley in central Europe

Water level appears to be crucial for waterbirds, especially in the changeable conditions prevailing in river valleys. One of the best preserved Central European rivers is the Biebrza in north-eastern Poland, which seasonally overflows in spring, creating optimal habitats for various waterbirds. We examined a number of environmental factors which could strongly influence different foraging groups and bird assemblages with respect to water surface area and depth. Number of waterbirds peaked during the second half of March, when a large wave of geese and ducks stopped over there. The species diversity was the greatest in the first half of April, when more species arrived from their wintering grounds. We did not find any relationship between water depth and total abundance, but the former did significantly influence the numbers of some ecological feeding groups of waterbirds, i.e. diving omnivores, diving carnivores and surface carnivores. We assume that higher water level in a river valley is favourable to birds during their spring passage, because it creates areas of shallow floodwater that are intensively used by many different aquatic species. Owing to the well-preserved hydrological conditions and its full protection as a national park, the Biebrza valley not only offers optimal conditions for migratory waterbirds, but is also a good research area for studies of the phenomena taking place in avian communities during their migratory staging.

Surgical amputation of a limb 31,000 years ago in Borneo

The prevailing view regarding the evolution of medicine is that the emergence of settled agricultural societies around 10,000 years ago (the Neolithic Revolution) gave rise to a host of health problems that had previously been unknown among non-sedentary foraging populations, stimulating the first major innovations in prehistoric medical practices1,2. Such changes included the development of more advanced surgical procedures, with the oldest known indication of an ‘operation’ formerly thought to have consisted of the skeletal remains of a European Neolithic farmer (found in Buthiers-Boulancourt, France) whose left forearm had been surgically removed and then partially healed3. Dating to around 7,000 years ago, this accepted case of amputation would have required comprehensive knowledge of human anatomy and considerable technical skill, and has thus been viewed as the earliest evidence of a complex medical act3. Here, however, we report the discovery of skeletal remains of a young individual from Borneo who had the distal third of their left lower leg surgically amputated, probably as a child, at least 31,000 years ago. The individual survived the procedure and lived for another 6–9 years, before their remains were intentionally buried in Liang Tebo cave, which is located in East Kalimantan, Indonesian Borneo, in a limestone karst area that contains some of the world’s earliest dated rock art4. This unexpectedly early evidence of a successful limb amputation suggests that at least some modern human foraging groups in tropical Asia had developed sophisticated medical knowledge and skills long before the Neolithic farming transition.

The Ornaments of the Arma Veirana Early Mesolithic Infant Burial

Personal ornaments are widely viewed as indicators of social identity and personhood. Ornaments are ubiquitous from the Late Pleistocene to the Holocene, but they are most often found as isolated objects within archaeological assemblages without direct evidence on how they were displayed. This article presents a detailed record of the ornaments found in direct association with an Early Mesolithic buried female infant discovered in 2017 at the site of Arma Veirana (Liguria, Italy). It uses microscopic, 3D, and positional analyses of the ornaments as well as a preliminary perforation experiment to document how they were perforated, used, and what led to their deposit as part of the infant’s grave goods. This study provides important information on the use of beads in the Early Mesolithic, in general, as well as the relationship between beads and young subadults, in particular. The results of the study suggest that the beads were worn by members of the infant’s community for a considerable period before they were sewn onto a sling, possibly used to keep the infant close to the parents while allowing their mobility, as seen in some modern forager groups. The baby was then likely buried in this sling to avoid reusing the beads that had failed to protect her or simply to create a lasting connection between the deceased infant and her community.

Le Moustérien du Zagros : une vision synthétique à partir de la grotte de Shanidar

The Zagros Mousterian is a Middle Palaeolithic techno-typological lithic complex, found down the length of the Zagros mountain range in Iraq and Iran. It is associated with Neanderthal skeletal remains at four sites, most famously Shanidar Cave. Dating is problematic, but the indications are that Neanderthals with this cultural apparatus were present in the Zagros region from the beginning of the last interglacial (Marine Isotope Stage 5e) c.130.000 years ago through to c. 40.000 years ago during the last glacial. The humid deciduous woodland of MIS 5 was replaced by increasingly dry steppe in MIS 4 and MIS 3. Microfaunal assemblages and paleosols indicate that Neanderthals visited Shanidar Cave when environmental conditions were broadly similar to those of today, primarily in the humid phases of MIS 5 and then during brief climatic ameliorations in MIS 4 and MIS 3 that may correlate with Dansgaard-Oescheger events. Caves with Mousterian occupations at high altitudes suggest that they, too, were used by Neanderthals when conditions were not dissimilar to those of today. The indications are that the Zagros Mousterian represents the seasonal activities of highly mobile small and dispersed groups of Neanderthal foragers connected in social networks of shared cultural values and/or norms.

Against Method

Against Method

Growing Up Urban: Hyena Foraging Groups and Social Structure at a City Waste Dump

Urban spotted hyenas (Crocuta crocuta) in Ethiopia are a prime example of large carnivores coexisting with little to no conflict with people in a human-dominated landscape, providing a valuable waste-removal service. To gain insight in how this urban lifestyle persists across generations, we studied hyena group composition at the city waste dump of Mekelle, a regional capital in northern Ethiopia. We found that hyena cubs and sub-adults foraged with adults in groups of highly variable composition. Young urban hyenas already take part in a fission-fusion dynamic that is also characteristic of hyenas in non-urban environments. They do not seem to learn from only one or few close reference adults. Social network analysis revealed no clusters among these dump-visiting hyenas. The number of counted hyenas is furthermore larger than any hyena clan in non-urban areas. All individuals were more or less equally connected to each other, and each hyena had a few connections, but to different individuals. All cubs and sub-adults were connected to each other, over a maximum of four links. Hyenas shared the abundance of food at the waste dump without overt aggression. A much larger number of urban hyenas shares this waste dump at night than would fit into a single forest fragment, such as those associated with orthodox churches where small groups of hyenas have often been observed to rest at daytime. Hyenas appear to commute from different dens and resting sites located around the city, but we have no information on their behavior and group composition away from the dump. We observed no defense of any part of the dump area by any of the foraging groups. In absence of territorial behavior at this city site, the clan concept does not seem to apply to these urban hyenas. Similar to what has been observed in other urban carnivores, individuals at the waste dump behaved as members of conflict-free foraging groups ostensibly sharing food without aggression. Perhaps this is what most strikingly defines their urbanity.

High Exploration Behavior of Termite Propagules Can Enhance Invasiveness

Social life is usually associated with enhanced propagule pressure, which increases the chance of introducing several individuals during a single introduction event. Social insects are therefore among the most successful invasive species, benefiting from rapid establishment and increased foundation success in new habitats. In termites, propagule pressure may also be increased by the development of reproductive individuals from a small group of foraging workers. This suggests that enhanced exploration activity may increase propagule pressure through an elevated chance of transporting isolated groups of foragers. Here, we analyzed the exploration behavior of three termite species of the Reticulitermes genus, comparing the invasive species Reticulitermes flavipes (testing both native and introduced populations) to the native species Reticulitermes grassei and Reticulitermes lucifugus. Different features representative of the exploration capacity were measured during 48 h, including: the number of tunnels, the length of tunnels, the number of foragers, and the interindividual distance of foragers in a straight line or through tunnels. Our results show that compared to the native Reticulitermes species, R. flavipes foragers from both populations dug more tunnels with a longer total length, and individuals were more spatially dispersed and covered a larger exploration zone. These findings suggest that the enhanced exploration ability of R. flavipes may have played a role in its invasion success, by increasing its propagule pressure through a higher chance of human-mediated transport. In addition, the absence of differences between the native and introduced populations of R. flavipes suggests that the exploration behaviors facilitating the worldwide invasion of this species originated in its native range.

Human Resilience in the Face of Mid-Holocene Climate Change on the Central West Coast of South Africa

Abstract After the Last Glacial Maximum, important yet milder climatic trends continued to characterise the Holocene. None of them was more challenging to forager groups in the central west coast of South Africa than the mid-Holocene Altithermal (8200–4200 cal BP). Hot and dry weather and 1–3 m higher sea levels were thought once to have barred local foragers from this region because of a lack of sites dating to this period. Instead, this initial scenario reflected largely a sampling problem. Steenbokfontein Cave is one of a few sites with some of the largest mid-Holocene deposits, allowing insights into forager adaptations during this period. Results show high mobility over large distances and a terrestrial diet mostly dependant on small bovids, complemented with fewer coastal resources. Stone tool kits and lithic raw materials among various sites suggest that much evidence for mid-Holocene occupation is actually found near the local riparian systems.