Human behavioral ecology and niche construction.

We examine the relationship between niche construction theory (NCT) and human behavioral ecology (HBE), two branches of evolutionary science that are important sources of theory in archeology. We distinguish between formal models of niche construction as an evolutionary process, and uses of niche construction to refer to a kind of human behavior. Formal models from NCT examine how environmental modification can change the selection pressures that organisms face. In contrast, formal models from HBE predict behavior assuming people behave adaptively in their local setting, and can be used to predict when and why people engage in niche construction. We emphasize that HBE as a field is much broader than foraging theory and can incorporate social and cultural influences on decision-making. We demonstrate how these approaches can be formally incorporated in a multi-inheritance framework for evolutionary research, and argue that archeologists can best contribute to evolutionary theory by building and testing models that flexibly incorporate HBE and NCT elements.

The effect of leprotic infection on the risk of death in medieval rural Denmark.

INTRODUCTION: Paleopathological studies of leprosy in Danish skeletal collections show that many individuals suffered from this stigmatized disease during the Middle Ages. This study examines the risk of death associated with leprotic infection in individuals from the Danish rural cemetery of Øm Kloster (AD 1172-1536). Specifically, we modeled the influence of leprotic infection on age-specific mortality accounting also for sex and social status (lay person / monastic). MATERIALS AND METHODS: The sample consisted of 311 adult individuals from the Øm Kloster skeletal collection housed at the Institute of Forensic Medicine, University of Southern Denmark (ADBOU). We modeled morbidity and mortality using a three-state illness-death model with the following parameterizations for the three transition hazards: (1) nonlesioned to lesioned: constant; (2) nonlesioned to dead: Gompertz-Makeham; and (3) lesioned to dead: Gompertz-Makeham, directly proportional to the hazard of the well to dead transition. RESULTS: The mortality hazard of lesioned individuals exceeded that of nonlesioned individuals by a factor of 1.4 (40%) across all individuals, 1.7 for females, 1.0 for males, 1.3 for lay persons, and 1.7 for monastics. Overall, 15% of the sample died with skeletal manifestations of leprosy, though it is likely that a higher percentage of the population carried the bacterium. DISCUSSION: This study improves understanding of past health and population dynamics focusing on a chronic infectious disease. The methods employed could informatively be applied to larger analyses of community health from skeletal collections by incorporating more than one disease into the multistate model and inferring individual frailty using various skeletal markers.

Fitness-maximizers employ pessimistic probability weighting for decisions under risk.

The standard theory of rationality posits that agents order preferences according to average utilities associated with different choices. Expected utility theory has repeatedly failed as a predictive theory, as reflected in a growing literature in behavioural economics. Evolutionary theorists have suggested that seemingly irrational behaviours in contemporary contexts may have once served important functions, but existing work linking fitness and choice has not adequately addressed the challenges of constructing an evolutionary theory of decision making. In particular, fitness itself is not a reasonable metric for decision making since its timescale exceeds the lifespan of the decision-maker. Consequently, organisms use proximate systems that work on appropriate timescales and are amenable to feedback and learning. We develop an evolutionary principal-agent model in which individuals utilize a set of proximal choice variables to account for the non-linear dependence of these variables on consumption. While this is insufficient to maximize fitness in the presence of environmental stochasticity, maximum fitness can be achieved by adopting pessimistic probability weightings compatible with the rank-dependent expected utility family of choice models. In particular, pessimistic probability weighting emerges naturally in an evolutionary framework because of extreme intolerance to zeros in multiplicative growth processes.

Scale and information-processing thresholds in Holocene social evolution.

Throughout the Holocene, societies developed additional layers of administration and more information-rich instruments for managing and recording transactions and events as they grew in population and territory. Yet, while such increases seem inevitable, they are not. Here we use the Seshat database to investigate the development of hundreds of polities, from multiple continents, over thousands of years. We find that sociopolitical development is dominated first by growth in polity scale, then by improvements in information processing and economic systems, and then by further increases in scale. We thus define a Scale Threshold for societies, beyond which growth in information processing becomes paramount, and an Information Threshold, which once crossed facilitates additional growth in scale. Polities diverge in socio-political features below the Information Threshold, but reconverge beyond it. We suggest an explanation for the evolutionary divergence between Old and New World polities based on phased growth in scale and information processing. We also suggest a mechanism to help explain social collapses with no evident external causes.

Are there differences in HIV retention in care between female and male patients in Indonesia? A multi-state analysis of a retrospective cohort study.

BACKGROUND: Little is known about HIV treatment outcomes in Indonesia, which has one of the most rapidly growing HIV epidemics worldwide. METHODS: We examined possible differences in loss to follow-up (LTFU) and survival between HIV-infected females and males over a 7-year period in an HIV clinic in Bandung, West Java. Data imputation was performed on missing covariates and a multi-state Cox regression was used to investigate the effects of sex and other covariates on patient transitions among four states: (1) clinic enrollment with HIV, (2) initiation/continuation/re-initiation of antiretroviral therapy (ART), (3) LTFU, and (4) death. RESULTS: We followed 3215 patients (33% females), for a total of 8430 person-years. ART was used by 59% of patients at some point. One-year retention was 73% for females and 77% for males (p = 0.06). One-year survival was 98% for both females and males (p = 0.15). Females experienced a higher relative hazard to transition from HIV to LTFU (adjusted hazard ratio 1.21; 95% confidence interval 1.00-1.45), but this decreased after adjustments for clinical variables (aHR 0.94; 95% CI 0.79-1.11). Similarly, a lower relative hazard in females to transition from ART to death (aHR 0.59; 95% CI 0.35-0.99) decreased after adjustments for demographic variables. CONCLUSION: This Indonesian cohort has low ART uptake and poor overall pre- and post-ART retention. Female-male differences in survival and retention were gone after adjusting for clinical and sociodemographic factors such as CD4 count and education level. Efforts should be made to improve retention among patients with lower education.