Saturday, October 1, 2022

Ancient DNA suggests that artificial islands were party spots for the elite

New integrated molecular approaches for investigating lake settlements in north-western Europe. Antony G. Brown et al. Antiquity, Sep 28 2022.

Abstract: Lake settlements, particularly crannogs, pose several contradictions—visible yet inaccessible, widespread yet geographically restricted, persistent yet vulnerable. To further our understanding, we have developed the integrated use of palaeolimnological (scanning XRF, pollen, spores, diatoms, chironomids, Cladocera, microcharcoal, biogenic silica, SEM-EDS, stable-isotopes) and biomolecular (faecal stanols, bile acids, sedaDNA) analyses of proximal and through-crannog cores in south-west Scotland and Ireland. Both can be effective methods sets for revealing occupation chronologies and identifying on-crannog activities and practices. Strong results from sedaDNA and lipid biomarker analyses demonstrate probable on-site animal slaughter, food storage and possible feasting, suggesting multi-period, elite site associations, and the storage and protection of valuable resources.

Context and discussion

The scientific techniques outlined here can provide sophisticated insights into the lifeways of societies ranging from the Neolithic to the post-medieval periods (AD 1603–present), even if via the cultural filter of wetland site activities. A key task for future work is to integrate these environmental methods with the more representative evidence generated by excavation of crannog settlements and associated dryland sites, and their wider cultural contexts. Focusing more specifically on crannogs, the frequent identification of ‘high-status’ activities and goods on some of these sites not only supports their role as places for the protective custody of valuable resources, but also suggests a degree of social exclusion combined with the display of power and wealth (O'Sullivan Reference O'Sullivan2004). Although seemingly low-status crannogs have been recorded, such as Sroove in Ireland (Boyle Reference Boyle2004), this impression may be the result of later reuse and disturbance, as the scale of resources required for crannog construction implies considerable investment. Indeed, biomolecular (and geochemical) methods may also be able to identify earlier activities that have left no trace in the on-site material culture, particularly as this could include infrequent events, such as feasting or ceremonial activities.

Shelley (Reference Shelley2009) has shown that for the medieval period in Scotland, crannogs can be regarded as watery lodges or palaces, which later went out of fashion as display became increasingly mediated through estates, mansions and gardens. The royal association of many crannogs suggests that this status display may also have been a factor during earlier periods in both Scotland and Ireland. Similarly, there was ecclesiastical use of some crannogs—especially in the early medieval period (AD 410–1066), following the model of ascetic monasticism whereby a central monastery was surrounded by satellite hermitages in remote locations and, particularly, on islands—although this was far more variable in Ireland (Bitel Reference Bitel, Alison and Bitel2020). An additional element here is the early Christian tradition of islands as places of holiness, retreat and redemption—a practise which can also have practical advantages through a degree of protection and self-sufficiency. Religious associations are visible through artefacts, such as crosses, and the later documented use of crannogs by the Church (Shelley Reference Shelley2009; Stratigos & Noble Reference Stratigos and Nobel2015). All of these considerations imply that the use and importance of crannogs were highly variable in different periods and places. One implication is that there is a fundamental limit to what we can discover about crannogs by studying them in isolation. A key insight comes from their changing use over time, but this relies entirely on increasing the number of dated crannogs, dating their construction and reuse, and comparing these dates to nearby dryland sites (e.g. settlements, raths and ringforts).

Non-conformity in mate choice: Immigrant females who do not conform to the local trend have sons, grandsons, etc. of the non-preferred phenotype, which negatively and cumulatively affects fitness over generations

Conformity in mate choice, the overlooked social component of animal and human culture. Sabine Nöbel et al. Biological Reviews, September 29 2022.

Abstract: Although conformity as a major driver for human cultural evolution is a well-accepted and intensely studied phenomenon, its importance for non-human animal culture has been largely overlooked until recently. This limited for decades the possibility of studying the roots of human culture. Here, we provide a historical review of the study of conformity in both humans and non-human animals. We identify gaps in knowledge and propose an evolutionary route towards the sophisticated cultural processes that characterize humanity. A landmark in the study of conformity is Solomon Asch's famous experiment on humans in 1955. By contrast, interest in conformity among evolutionary biologists has only become salient since the turn of the new millennium. A striking result of our review is that, although studies of conformity have examined many biological contexts, only one looked at mate choice. This is surprising because mate choice is probably the only context in which conformity has self-reinforcing advantages across generations. Within a metapopulation, i.e. a group of subpopulations connected by dispersing individuals, dispersers able to conform to the local preference for a given type of mate have a strong and multigenerational fitness advantage. This is because once females within one subpopulation locally show a bias for one type of males, immigrant females who do not conform to the local trend have sons, grandsons, etc. of the non-preferred phenotype, which negatively and cumulatively affects fitness over generations in a process reminiscent of the Fisher runaway process. This led us to suggest a sex-driven origin of conformity, indicating a possible evolutionary route towards animal and human culture that is rooted in the basic, and thus ancient, social constraints acting on mating preferences within a metapopulation. In a generic model, we show that dispersal among subpopulations within a metapopulation can effectively maintain independent Fisher runaway processes within subpopulations, while favouring the evolution of social learning and conformity at the metapopulation scale; both being essential for the evolution of long-lasting local traditions. The proposed evolutionary route to social learning and conformity casts surprising light on one of the major processes that much later participated in making us human. We further highlight several research avenues to define the spectrum of conformity better, and to account for its complexity. Future studies of conformity should incorporate experimental manipulation of group majority. We also encourage the study of potential links between conformity and mate copying, animal aggregations, and collective actions. Moreover, validation of the sex-driven origin of conformity will rest on the capacity of human and evolutionary sciences to investigate jointly the origin of social learning and conformity. This constitutes a stimulating common agenda and militates for a rapprochement between these two currently largely independent research areas.


(1) The strength of our proposed pathway rooted in mate choice and runaway sexual selection is that it explains the evolution of social learning and conformity, as well as culture.

(2) One of the major challenges therefore for empirical studies of social learning is to find out whether the detection of majority behaviour in mate copying preceded (in evolutionary time) the detection of majority behaviour in other contexts such as foraging and to what extent it evolved analogously or homologously. For that goal we will need to determine in a large range of species the shape of the response function of conformity in mate choice, and other contexts with experiments manipulating the level of majority. Altogether, this provides a rich agenda for future research.

(3) In the expectation of such information, the tentative model we propose and simulate here for the evolution of conformity, and all its cultural evolution consequences, casts surprising light on one of the major processes that has participated in making us humans. Sex might play a bigger role than previously thought in the long-run development of cultural traditions.

Placebo Analgesia not only reduces empathy, also Reduces Costly Prosocial Helping to Lower Another Person’s Pain

Placebo Analgesia Reduces Costly Prosocial Helping to Lower Another Person’s Pain. Helena Hartmann et al. Psychological Science, Sep 29 2022.

Abstract: Painkiller administration lowers pain empathy, but whether this also reduces prosocial behavior is unknown. In this preregistered study, we investigated whether inducing analgesia through a placebo painkiller reduced effortful helping. When given the opportunity to reduce the pain of another person, individuals experiencing placebo analgesia (n = 45 adults from Austria; 21 male, 24 female) made fewer prosocial choices at the lowest helping level and exerted less physical effort when helping, compared with controls whose pain sensitivity was unaltered (n = 45; 21 male, 24 female). Self-reported empathic unpleasantness positively correlated with prosocial choices across the whole sample. While not replicating group differences in empathy, a mediation analysis revealed that the level of unpleasantness to other people’s pain fully mediated the effect of placebo analgesia on prosocial choices. Given the importance of prosociality for social cohesion, these findings have broad potential implications both for individuals under the influence of painkillers and for society at large.