Evolution, Medicine, and Public Health最新文献

The Chiari malformation type I (CM-I) is a herniation of the cerebellum through the foramen magnum. Its proximate cause is accepted to be an unusually small occipital bone. However, its ultimate cause remains unclear. In 2013, Fernandes and colleagues hypothesized that individuals develop CM-I because some of their cranial development-coding genes derive from three extinct Homo species that have smaller basicrania than is typical for modern humans-Homo erectus, Homo heidelbergensis, and Homo neanderthalensis. Here, we report a study in which we used 3D data and Geometric Morphometrics to evaluate this hypothesis. We began by investigating whether CM-I is associated with significant differences in cranial shape in a sample of living humans. Subsequently, we compared the crania of living humans with and without CM-I to fossil crania assigned to H. erectus, H. heidelbergenesis, H. neanderthalensis, and H. sapiens. The study's results were mixed. The first set of analyses identified significant shape differences between the crania of people with CM-I and the crania of unaffected people, which is in line with the hypothesis. In contrast, the second set of analyses did not support the hypothesis. They indicated that the crania of living humans with CM-I are only closer in shape to one of the extinct species, H. neanderthalensis. The other two extinct species were found to be closer in shape to living humans without CM-I. This is contrary to the main prediction of the hypothesis. Together, our results suggest the hypothesis should be narrowed to focus on introgressed genes from Neanderthals.

Background and objectives: Linking adult health to early life is limited by a lack of retrospective biomarkers of stress tied to narrow windows of early development. Teeth serve as ideal data sources to examine early life because their hard tissues endure from infancy through adulthood as permanent records of developmental stress. This study examines if dental fluctuating asymmetry (FA) in permanent molars, a measure of instability and plastic responses to stress, is associated with biocultural factors during development.

Methodology: Data were sourced from dental casts and health history records of 303 child participants of the longitudinal Burlington Growth Study. Dental FA was calculated from the first and second permanent molar intercuspal distances. Biocultural factors of parental, gestational, and childhood characteristics were grouped into latent dimensions using factor analysis of mixed data, then analyzed against FA using logistic regression separated by sex.

Results: Breastfeeding and high and low parental socioeconomic status were associated with lower FA in females. No relationships were found between biocultural factors and FA in males.

Conclusion and implications: The sex-specific results are likely due to differences in the nutritional needs of males and females during the first several postnatal months. Furthermore, dimorphism in energetic investment strategies, where males favor body growth while females favor system development, may be responsible for differences in how periods of physiological stress affect biological systems. These results argue for sex-specific investigations of stress biomarkers to better link early life with adult health.

The rise in chronic diseases over the last century presents a significant health and economic burden globally. Here, we apply evolutionary medicine and life history theory to better understand their development. We highlight an imbalanced metabolic axis of growth and proliferation (anabolic) versus maintenance and dormancy (catabolic), focusing on major mechanisms including IGF-1, mTOR, AMPK, and Klotho. We also relate this axis to the hyperfunction theory of aging, which similarly implicates anabolic mechanisms such as mTOR in aging and disease. Next, we highlight the Brain-Body Energy Conservation model, which connects the hyperfunction theory with energetic trade-offs that induce hypofunction and catabolic health risks such as impaired immunity. Finally, we discuss how modern environmental mismatches exacerbate this process. Following our review, we discuss future research directions to better understand health risk. This includes studying IGF-1, mTOR, AMPK, and Klotho and how they relate to health and aging in human subsistence populations, including with lifestyle shifts. It also includes understanding their role in the developmental origins of health and disease as well as the social determinants of health disparities. Furthermore, we discuss the need for future studies on exceptionally long-lived species to understand potentially underappreciated trade-offs and costs that come with their longevity. We close with considering possible implications for therapeutics, including (i) compensatory pathways counteracting treatments, (ii) a "Goldilocks zone," in which suppressing anabolic metabolism too far introduces catabolic health risks, and (iii) species constraints, in which therapeutics tested in shorter lived species with greater anabolic imbalance will be less effective in humans.

Global water insecurity and rising heat indices have a significant impact on human health. There is an urgent need to understand these climate impacts on the most physiologically and socially vulnerable populations across the globe and use this information to strengthen evidence-based responses. Pregnancy, postpartum, and the first year of life are especially sensitive to water insecurity and extreme heat exposures, as these stages require significantly more access to hydration and cooling resources than other life stages. Extreme heat and water insecurity are ecological stressors forcing parents and alloparents to make difficult decisions between optimal practices for survival and reducing human suffering. Additionally, these stressors may impose physiological trade-offs at the cost of reproductive performance. Here, we examine the changing effects of water insecurity and heat stress throughout pregnancy and lactation using an interdisciplinary, evolutionary, and biocultural lens. We highlight the importance of an evolutionary medicine framework in efforts to investigate the effects of climate change on global health equity. In addition, we outline implications for public health emphasizing the need for targeted policies and healthcare strategies to support pregnant individuals and lactating individuals in affected regions. By integrating evolutionary perspectives with global health concerns, this paper aims to inform future research agendas and policy frameworks aimed at enhancing resilience and adaptation among populations facing escalating climate challenges during critical reproductive phases.

[This corrects the article DOI: 10.1093/emph/eoaf001.].

Research in industrialized populations suggests that posttraumatic stress disorder (PTSD) may be associated with decreased cortisol or testosterone sensitivity, resulting in a blunted diurnal rhythm. However, the evolutionary implications of this association are unclear. Studies have primarily been conducted in Western industrialized populations, so we do not know whether hormonal blunting is a reliable physiological response to PTSD or stems from factors unique to industrialized settings. Furthermore, existing studies combine PTSD from diverse types of traumas, and comparison groups with and without PTSD differ along multiple dimensions, making it hard to know if PTSD or other life factors drive the blunted cortisol response. We conducted a study among n = 60 male Turkana pastoralists, aged between about 18-65 years in Kenya, exposed to high levels of lethal inter-ethnic cattle raiding. 28% of men in this area have PTSD symptom severity that would qualify them for a provisional PTSD diagnosis. Saliva samples were collected at three points to compare the cortisol and testosterone profiles of Turkana warriors with and without PTSD. Contrary to existing work, our preregistered analysis found little evidence for a difference in the hormonal profiles of warriors with high versus low PTSD symptom severity. Our results imply that the relationship between PTSD and hormonal diurnal variation may vary across populations and ecologies or that the association documented in Western populations stems from other correlated life factors. Studies in a wider range of populations and ecological contexts are needed to understand the evolutionary underpinnings of hormonal responses to trauma.

Background and objectives: Pregnancy, heat stress, and physical activity (PA) are all known to independently increase human water requirements. We hypothesize that climate conditions and behavioral strategies interact to shape water needs in highly active pregnancies.

Methodology: We recruited 20 female endurance runners who were pregnant (8-16 weeks gestational age; n = 13) or planning to be pregnant (n = 7) for an observational, prospective cohort study. At three timepoints in the study (preconception, 8-16 weeks, and 32-35 weeks), we measured water turnover (WT) using the deuterium dilution and elimination technique, PA using ActiGraph wGT3X-BT accelerometers, and heat index (HI) using historical temperature and humidity data. We also compared athletes to nonathletes from a previously published study.

Results: Athletes maintained high WT from preconception through the end of pregnancy. PA was positively associated with WT among athletes for preconception and early pregnancy time periods but not for the third trimester. HI weakly moderated the relationship between PA and WT in predicting a more positive slope in hotter and more humid weather conditions. WT in athletes was higher than in nonathletes, but this difference attenuated during the third trimester, as nonathletes increased their WT.

Conclusions and implications: Athletes experience higher WT with greater levels of PA, and this relationship is somewhat stronger in higher HI conditions. With the threat of climate change expected to exacerbate extreme heat conditions, evidence-based, global policies are required for particularly vulnerable populations.

Viruses differ in the number and types of host tissues in which they replicate. For example, systemically replicating viruses such as measles infect cells and tissues throughout the body, whereas respiratory viruses such as influenza viruses and coronaviruses replicate only in the respiratory tract. Reinfections with respiratory viruses are thought to be driven by ongoing antigenic immune escape in the viral population. However, this does not explain why antigenic variation is frequently observed in respiratory viruses and not systemically replicating viruses. Here, we argue that the rapid rate of waning immunity in the respiratory tract is a key driver of antigenic evolution in respiratory viruses. Waning immunity results in hosts with immunity levels that protect against homologous reinfection but are insufficient to protect against infection with an antigenically different (heterologous) strain. Thus, when partially immune hosts are present at a high enough density, an immune escape variant can invade the viral population even though that variant cannot infect solidly immune hosts. Invasion can occur even when the variant's immune escape mutation incurs a fitness cost, although any such cost is likely to be short-lived from compensatory evolution. Thus, the mutant lineage may replace the wild type and, as immunity to it builds, the process will repeat. Our model provides a new explanation for the pattern of successive emergence and replacement of antigenic variants that has been observed in many respiratory viruses. We discuss our model relative to others for understanding the drivers of antigenic evolution in respiratory viruses.

Background and objectives: Research to identify fetal predictors of infant mortality among singletons born in the United States (US) concludes that poorly understood and unmeasured "confounders" produce a spurious association between fetal size and infant death. We argue that these confounders include Vanishing Twin Syndrome (VTS)-the clinical manifestation of selection against frail male twins in utero. We test our argument in 276 monthly conception cohorts conceived in the US from January 1995 through December 2017.

Methodology: We use Box-Jenkins transfer function modeling to test the hypothesis that among infants born from 276 monthly conception cohorts conceived in the US from January 1995 through December 2017, the sex ratio of twins born in the 37th week of gestation will correlate inversely with infant mortality among singleton males born at the 40th week of gestation.

Results: We find support for our hypothesis and infer that the contribution of survivors of VTS to temporal variation in infant mortality among the hardiest of singleton male infants, those born at 40 weeks gestation, ranged from a decrease of about 7% to an increase of about 5% over our 276 monthly conception cohorts.

Conclusions and implications: We conclude that an evolutionary perspective on fetal loss makes a heretofore "unmeasured confounder" of the relationship between fetal size and infant mortality both explicable and measurable. This finding may help clinicians better anticipate changes over time in the incidence of infant mortality.

Background and objectives: Rituals have been reported to serve as a vital mechanism for expressing grief and fostering communal support worldwide. Despite these benefits, use of rituals in Indigenous communities is threatened by missionization, globalization, and westernization. This study sought to examine the relevance of traditional mourning rituals in community morality and well-being. Anchored in cultural evolutionary theory, the study employed an ethnographic research design.

Methodology: Data were collected from 45 community elders, 30 bereaved adults, 30 bereaved adolescents, and 8 religious leaders through focus group discussions and interviews.

Results: The study established five mourning rituals practiced by the Luhya people, each potentially serving an evolutionary function for community survival and well-being. Our findings show that Luhya traditional mourning rituals play an important role in community well-being, though not all members may benefit equally from these effects.

Conclusions and implications: The study established conflict over rituals with differing viewpoints from religious leaders, cultural leaders, and the western biomedical approach to mental well-being. Yet, the bereaved reported that both Luhya and religious rituals helped them process their grief. To address mental health issues fully, it is important to establish collaboration between western models, religious approaches, and cultural approaches.