Child attachment in adjusting the species-general contingency between environmental adversities and fast life history strategies

Extrinsic mortality risks calibrating fast life history (LH) represent a species-general principle that applies to almost all animals including humans. However, empirical research also finds exceptions to the LH principle. The present study proposes a maternal socialization hypothesis, whereby we argue that the more human-relevant attachment system adds to the LH principle by up- and down-regulating environmental harshness and unpredictability and their calibration of LH strategies. Based on a longitudinal sample of 259 rural Chinese adolescents and their primary caregivers, the results support the statistical moderating effect of caregiver–child attachment on the relation between childhood environmental adversities (harshness and unpredictability) and LH strategies. Our theorizing and findings point to an additional mechanism likely involved in the organization and possibly the slowdown of human LH.

Predation has small, short-term, and in certain conditions random effects on the evolution of aging

Background The pace of aging varies considerably in nature. The best-known explanation of the evolution of specific rates of aging is the Williams’ hypothesis suggesting that the aging rate should correlate with the level of extrinsic mortality. However, the current evidence is inconclusive with various examples where the Williams' hypothesis seems to be correct and where it doesn’t. Here we explore the relationship between extrinsic mortality and aging rate by developing a simulation model of the evolution of aging rate in prey subject to predation. Results Our results suggest that more intense predation leads to the evolution of faster pace of aging in prey. However, this effect slowly vanishes when the predator diet breadth is allowed to evolve, too. Furthermore, in our model, the evolution of a specific aging rate is driven mainly by a single parameter, the strength of a trade-off between aging and fecundity. Indeed, in the absence of this trade-off the evolutionary impacts of predation on the prey aging rate appear random. Conclusions We show that the William’s hypothesis appears valid when there is a trade-off between aging and fecundity and predators and prey do not coevolve. However, we also show that when the prey and predators coevolve or if there is no trade-off between aging and fecundity the William`s hypothesis is no longer applicable.

COVID-19: the relationship between perceptions of risk and behaviours during lockdown

Aim Understanding COVID-19 risk perceptions and their impact on behaviour can improve the effectiveness of public health strategies. Prior evidence suggests that, when people perceive uncontrollable risks to their health, they are less likely to engage in healthful behaviour. This article aims to understand the extent to which COVID-19 is perceived as an uncontrollable risk, and to assess whether this perceived risk is associated with health behaviour. Subject and methods We surveyed a nationally representative sample of 496 participants during the first UK lockdown. We assessed perceptions of COVID-19-related risk, self-reported adherence to infection control measures recommended by the UK Government, and general health behaviours. We predicted that increased perceived extrinsic mortality risk (the portion of mortality risk perceived to be uncontrollable) would disincentivise healthy behaviour. Results Perceived threat to life was the most consistent predictor of reported adherence to infection control measures. Perceived extrinsic mortality risk was found to have increased due to the pandemic, and was associated with lower reported adherence to Government advice on diet, physical activity, and smoking. Conclusions Our findings suggest that health messages that highlight threat to life may be effective in increasing adherence to infection control, but may also lead to a reduction in health-promoting behaviours. We suggest that messages that highlight threat to life should be accompanied by statements of efficacy. Further, messages evoking feelings of concern for others may be effective in promoting compliance with anti-infection measures, without the potential for the unwelcome side-effect of discouraging healthy behaviour.

Gene co-expression network reveals highly conserved, well-regulated anti-ageing mechanisms in old ant queens

Evolutionary theories of ageing predict a reduction in selection efficiency with age, a so-called ‘selection shadow’, due to extrinsic mortality decreasing effective population size with age. Classic symptoms of ageing include a deterioration in transcriptional regulation and protein homeostasis. Understanding how ant queens defy the trade-off between fecundity and lifespan remains a major challenge for the evolutionary theory of ageing. It has often been discussed that the low extrinsic mortality of ant queens, that are generally well protected within the nest by workers and soldiers, should reduce the selection shadow acting on old queens. We tested this by comparing strength of selection acting on genes upregulated in young and old queens of the ant, Cardiocondyla obscurior. In support of a reduced selection shadow, we find old-biased genes to be under strong purifying selection. We also analysed a gene co-expression network (GCN) with the aim to detect signs of ageing in the form of deteriorating regulation and proteostasis. We find no evidence for ageing. In fact, we detect higher connectivity in old queens indicating increased transcriptional regulation with age. Within the GCN, we discover five highly correlated modules that are upregulated with age. These old-biased modules regulate several anti-ageing mechanisms such as maintenance of proteostasis, transcriptional regulation and stress response. We observe stronger purifying selection on central hub genes of these old-biased modules compared to young-biased modules. These results indicate a lack of transcriptional ageing in old C. obscurior queens possibly facilitated by strong selection at old age and well-regulated anti-ageing mechanisms.

Gene co-expression network reveals highly conserved, well-regulated anti-ageing mechanisms in old ant queens

Evolutionary theories of ageing predict a reduction in selection efficiency with age, a so-called ‘selection shadow’, due to extrinsic mortality decreasing effective population size with age. Classic symptoms of ageing include a deterioration in transcriptional regulation and protein homeostasis. Understanding how ant queens defy the trade-off between fecundity and lifespan remains a major challenge for the evolutionary theory of ageing. It has often been discussed that the low extrinsic mortality of ant queens, that are generally well protected within the nest by workers and soldiers, should reduce the selection shadow acting on old queens. We tested this by comparing strength of selection acting on genes upregulated in young and old queens of the ant, Cardiocondyla obscurior. In support of a reduced selection shadow, we find old-biased genes to be under strong purifying selection. We also analysed a gene co-expression network (GCN) with the aim to detect signs of ageing in the form of deteriorating regulation and proteostasis. We find no evidence for ageing. In fact, we detect higher connectivity in old queens indicating increased transcriptional regulation with age. Within the GCN, we discover five highly correlated modules that are upregulated with age. These old-biased modules regulate several anti-ageing mechanisms such as maintenance of proteostasis, transcriptional regulation and stress response. We observe stronger purifying selection on central hub genes of these old-biased modules compared to young-biased modules. These results indicate a lack of transcriptional ageing in old C. obscurior queens possibly facilitated by strong selection at old age and well-regulated anti-ageing mechanisms.

Disease History and Life History Predict Behavioral Control of the COVID-19 Pandemic

It is puzzling why countries do not all implement stringent behavioral control measures to prevent the spread of COVID-19 even though preventive behaviors have been proven to be the only effective means to stop the pandemic. We provide a novel evolutionary life history explanation whereby pathogenic and parasitic prevalence represents intrinsic rather than extrinsic mortality risk that drives slower life history strategies and the related disease control motivation in all animals but especially humans. Our theory was tested and supported based on publicly available data involving over 150 countries. Countries having a higher historical prevalence of infectious diseases are found to adopt slower life history strategies that are related to prompter COVID-19 containment actions by the government and greater compliance by the population. Findings could afford governments novel insight into the design of more effective COVID-19 strategies that are based on enhancing a sense of control, vigilance, and compliance in the general population.

Famine-related mortality in early life and accelerated life histories in nineteenth-century Belgium

Density-dependent and extrinsic mortality are predicted to accelerate reproductive maturation. The first 5 years of life is a proposed sensitive period for life-history regulation. This study examines the ways in which local mortality during this sensitive period was related to subsequent marriage timing in nineteenth-century Belgium ( n women = 11 892; n men = 14 140). Local mortality during the sensitive period was inversely associated with age at first marriage for men and women controlling for literacy, occupational status, population growth and migration. Cox regression indicated decreased time to marriage for women (HR = 1.661, 95% CI: 1.542–1.789) and men (HR = 1.327, 95% CI: 1.238–1.422) from high mortality municipalities. Rising population growth rates were associated with earlier marriage for men and women. Migration in general was associated with later marriage for men and women. Consistent with life-history predictions, harsh ecological conditions during early life such as famine coincided with earlier marriage.

The sensitivity of a honeybee colony to worker mortality depends on season and resource availability

Background Honeybees have extraordinary phenotypic plasticity in their senescence rate, making them a fascinating model system for the evolution of aging. Seasonal variation in senescence and extrinsic mortality results in a tenfold increase in worker life expectancy in winter as compared to summer. To understand the evolution of this remarkable pattern of aging, we must understand how individual longevity scales up to effects on the entire colony. In addition, threats to the health of honey bees and other social insects are typically measured at the individual level. To predict the effects of environmental change on social insect populations, we must understand how individual effects impact colony performance. We develop a matrix model of colony demographics to ask how worker age-dependent and age-independent mortality affect colony fitness and how these effects differ by seasonal conditions. Results We find that there are seasonal differences in honeybee colony elasticity to both senescent and extrinsic worker mortality. Colonies are most elastic to extrinsic (age-independent) nurse and forager mortality during periods of higher extrinsic mortality and resource availability but most elastic to age-dependent mortality during periods of lower extrinsic mortality and lower resource availability. Conclusions These results suggest that seasonal changes in the strength of selection on worker senescence partly explain the observed pattern of seasonal differences in worker aging in honey bees. More broadly, these results extend our understanding of the role of extrinsic mortality in the evolution of senescence to social animals and improve our ability to model the effects of environmental change on social insect populations of economic or conservation concern.