Robustness assessment of the ‘cooperation under resource pressure’ (CURP) model: Insights on resource availability and sharing practices among hunter-gatherers

A well-known challenge in archaeological research is the exploration of the social mechanisms that hunter-gatherers may have implemented throughout history to deal with changes in resource availability. The agent-based model (ABM) ‘cooperation under resource pressure’ (CURP) was conceived to explore food stress episodes in societies lacking a food preservation technology. It was particularly aimed at understanding how cooperative behaviours in the form of food sharing practices emerge, increase and may become the prevailing strategy in relation to changes in resource availability and expectancy of reciprocity. CURP’s main outcome is the identification of three regimes of behaviour depending on the stress level. In this work, the model’s robustness to the original selection mechanism (random tournament) is assessed, as different dynamics can lead to different persistent regimes. For that purpose, three other selection mechanisms are implemented and evaluated, to identify the prevailing states of the system. Results show that the three regimes are robust irrespective of the analysed dynamics. We consequently examine in more detail the long-term archaeological implications that these results may have.Spanish Ministry of Economy and Competitiveness (former Ministry of Science and Innovation): SimulPast Project (CSD2010- 00034 CONSOLIDER-INGENIO 2010), HAR2009-06996 and CULM Project (HAR2016- 77672-P); from the Argentine National Scientific and Technical Research Council (CONICET): Project PIP-0706; from the Wenner-Gren Foundation for Anthropological Research: Project GR7846; from the project H2020 FET OPEN RIA IBSEN/662725 and from the European Social Fund as one of the authors is the recipient of a predoctoral grant from the Department of Education of Junta de Castilla y León (Spain)

Emergence and Evolution of Cooperation Under Resource Pressure

We study the influence that resource availability has on cooperation in the context of hunter-gatherer societies. This paper proposes a model based on archaeological and ethnographic research on resource stress episodes, which exposes three different cooperative regimes according to the relationship between resource availability in the environment and population size. The most interesting regime represents moderate survival stress in which individuals coordinate in an evolutionary way to increase the probabilities of survival and reduce the risk of failing to meet the minimum needs for survival. Populations self-organise in an indirect reciprocity system in which the norm that emerges is to share the part of the resource that is not strictly necessary for survival, thereby collectively lowering the chances of starving. Our findings shed further light on the emergence and evolution of cooperation in hunter-gatherer societies.Spanish Ministry of Science and Innovation Project CSD2010-00034 (SimulPast CONSOLIDER-INGENIO 2010) and HAR2009-06996; from the Argentine National Scientific and Technical Research Council (CONICET): Project PIP-0706; from the Wenner-Gren Foundation for Anthropological Research: Project GR7846; and from the project H2020 FET OPEN RIA IBSEN/66272

SDS Interferes with SaeS Signaling of Staphylococcus aureus Independently of SaePQ

<p>The Staphylococcus aureus regulatory saePQRS system controls the expression of numerous virulence factors, including extracellular adherence protein (Eap), which amongst others facilitates invasion of host cells. The saePQRS operon codes for 4 proteins: the histidine kinase SaeS, the response regulator SaeR, the lipoprotein SaeP and the transmembrane protein SaeQ. S. aureus strain Newman has a single amino acid substitution in the transmembrane domain of SaeS (L18P) which results in constitutive kinase activity. SDS was shown to be one of the signals interfering with SaeS activity leading to inhibition of the sae target gene eap in strains with SaeS(L) but causing activation in strains containing SaeS(P). Here, we analyzed the possible involvement of the SaeP protein and saePQ region in SDS-mediated sae/eap expression. We found that SaePQ is not needed for SDS-mediated SaeS signaling. Furthermore, we could show that SaeS activity is closely linked to the expression of Eap and the capacity to invade host cells in a number of clinical isolates. This suggests that SaeS activity might be directly modulated by structurally non-complex environmental signals, as SDS, which possibly altering its kinase/phosphatase activity.</p>