Opposite selection pressures on stature and intelligence across human populations

Background Humans life histories have been described as “slow”, patterned by slow growth, delayed maturity, and long life span. While it is known that human life history diverged from that of a recent common chimpanzee-human ancestor some ~4–8 mya, it is unclear how selection pressures led to these distinct traits. To provide insight, we compare wild chimpanzees and human subsistence societies in order to identify the age-specific vital rates that best explain fitness variation, selection pressures and species divergence. Methods We employ Life Table Response Experiments to quantify vital rate contributions to population growth rate differences. Although widespread in ecology, these methods have not been applied to human populations or to inform differences between humans and chimpanzees. We also estimate correlations between vital rate elasticities and life history traits to investigate differences in selection pressures and test several predictions based on life history theory. Results Chimpanzees’ earlier maturity and higher adult mortality drive species differences in population growth, whereas infant mortality and fertility variation explain differences between human populations. Human fitness is decoupled from longevity by postreproductive survival, while chimpanzees forfeit higher potential lifetime fertility due to adult mortality attrition. Infant survival is often lower among humans, but lost fitness is recouped via short birth spacing and high peak fertility, thereby reducing selection on infant survival. Lastly, longevity and delayed maturity reduce selection on child survival, but among humans, recruitment selection is unexpectedly highest in longer-lived populations, which are also faster-growing due to high fertility. Conclusion Humans differ from chimpanzees more because of delayed maturity and lower adult mortality than from differences in juvenile mortality or fertility. In both species, high child mortality reflects bet-hedging costs of quality/quantity tradeoffs borne by offspring, with high and variable child mortality likely regulating human population growth over evolutionary history. Positive correlations between survival and fertility among human subsistence populations leads to selection pressures in human subsistence societies that differ from those in modern populations undergoing demographic transition.

Download Full-text

Host-Virus Arms Races Drive Elevated Adaptive Evolution in Viral Receptors

Journal of Virology ◽

10.1128/jvi.00684-20 ◽

2020 ◽

Vol 94 (16) ◽

Cited By ~ 1

Author(s):

Wenqiang Wang ◽

Huayao Zhao ◽

Guan-Zhu Han

Keyword(s):

Positive Selection ◽

Local Adaptation ◽

Adaptive Evolution ◽

Negative Selection ◽

Host Cells ◽

Human Populations ◽

Arms Races ◽

Selection Pressures ◽

Selection For ◽

Viral Receptors

ABSTRACT Viral receptors are the cell surface proteins that are hijacked by viruses to initialize their infections. Viral receptors are subject to two conflicting directional forces, namely, negative selection due to functional constraints and positive selection due to host-virus arms races. It remains largely obscure whether negative pleiotropy limits the rate of adaptation in viral receptors. Here, we perform evolutionary analyses of 96 viral receptor genes in primates and find that 41 out of 96 viral receptors experienced adaptive evolution. Many positively selected residues in viral receptors are located at the virus-receptor interfaces. Compared with control proteins, viral receptors exhibit significantly elevated rate of adaptation. Further analyses of genetic polymorphisms in human populations reveal signals of positive selection and balancing selection for 53 and 5 viral receptors, respectively. Moreover, we find that 49 viral receptors experienced different selection pressures in different human populations, indicating that viruses represent an important driver of local adaptation in humans. Our findings suggest that diverse viruses, many of which have not been known to infect nonhuman primates, have maintained antagonistic associations with primates for millions of years, and the host-virus conflicts drive accelerated adaptive evolution in viral receptors. IMPORTANCE Viruses hijack cellular proteins, termed viral receptors, to assist their entry into host cells. While viral receptors experience negative selection to maintain their normal functions, they also undergo positive selection due to an everlasting evolutionary arms race between viruses and hosts. A complete picture on how viral receptors evolve under two conflicting forces is still lacking. In this study, we systematically analyzed the evolution of 96 viral receptors in primates and human populations. We found around half of viral receptors underwent adaptive evolution and exhibit significantly elevated rates of adaptation compared to control genes in primates. We also found signals of past natural selection for 58 viral receptors in human populations. Interestingly, 49 viral receptors experienced different selection pressures in different human populations, indicating that viruses represent an important driver of local adaptation in humans. Our results suggest that host-virus arms races drive accelerated adaptive evolution in viral receptors.

Download Full-text

The Three Ts of Pathogen Evolution During Zoonotic Emergence

10.32942/osf.io/tueyb ◽

2021 ◽

Author(s):

Elisa Visher ◽

Claire Evensen ◽

Sarah Guth ◽

Edith Lai ◽

Marina Norfolk ◽

...

Keyword(s):

Time Scales ◽

Time Scale ◽

Zoonotic Diseases ◽

Control Measures ◽

Effective Control ◽

Human Populations ◽

Selection Pressures ◽

Trade Off ◽

Pathogen Evolution ◽

Trade Offs

When novel zoonotic diseases like Sars-CoV-2 emerge, they are likely to be poorly adapted to humans. Effective control measures will suppress transmission before significant evolution can occur, but extended transmission in human populations allows time for selection pressures to act. In this review, we discuss these selection pressures with the aim of better understanding the factors shaping both transmission and virulence in zoonotic pathogens as they become established. We discuss how selection pressures during epidemics of emerging zoonotic disease are determined by the three Ts: trade-offs, transmission, and time scales. In short, virulence and transmission may trade-off, but transmission is likely to be favored by selection early in emergence. However, the relative selection pressures on transmission and virulence shift depending on the time scale of the epidemic. Predicting pathogen evolution in zoonoses therefore depends critically on understanding both the trade-offs of transmission-improving mutations and the time scales of selection.

Download Full-text

Controlling the SARS-CoV-2 outbreak, insights from large scale whole genome sequences generated across the world

10.1101/2020.04.28.066977 ◽

2020 ◽

Cited By ~ 12

Author(s):

Jody Phelan ◽

Wouter Deelder ◽

Daniel Ward ◽

Susana Campino ◽

Martin L. Hibberd ◽

...

Keyword(s):

Genome Sequencing ◽

Molecular Diagnostics ◽

Large Scale ◽

Vaccine Development ◽

Human Populations ◽

Whole Genome ◽

Selection Pressures ◽

Infected People ◽

The World ◽

Genome Sequencing Effort

ABSTRACTBackgroundSARS-CoV-2 most likely evolved from a bat beta-coronavirus and started infecting humans in December 2019. Since then it has rapidly infected people around the world, with more than 4.5 million confirmed cases by the middle of May 2020. Early genome sequencing of the virus has enabled the development of molecular diagnostics and the commencement of therapy and vaccine development. The analysis of the early sequences showed relatively few evolutionary selection pressures. However, with the rapid worldwide expansion into diverse human populations, significant genetic variations are becoming increasingly likely. The current limitations on social movement between countries also offers the opportunity for these viral variants to become distinct strains with potential implications for diagnostics, therapies and vaccines.MethodsWe used the current sequencing archives (NCBI and GISAID) to investigate 15,487 whole genomes, looking for evidence of strain diversification and selective pressure.ResultsWe used 6,294 SNPs to build a phylogenetic tree of SARS-CoV-2 diversity and noted strong evidence for the existence of two major clades and six sub-clades, unevenly distributed across the world. We also noted that convergent evolution has potentially occurred across several locations in the genome, showing selection pressures, including on the spike glycoprotein where we noted a potentially critical mutation that could affect its binding to the ACE2 receptor. We also report on mutations that could prevent current molecular diagnostics from detecting some of the sub-clades.ConclusionThe worldwide whole genome sequencing effort is revealing the challenge of developing SARS-CoV-2 containment tools suitable for everyone and the need for data to be continually evaluated to ensure accuracy in outbreak estimations.

Download Full-text

The bottleneck may be the solution, not the problem

Behavioral and Brain Sciences ◽

10.1017/s0140525x15000886 ◽

2016 ◽

Vol 39 ◽

Cited By ~ 1

Author(s):

Arnon Lotem ◽

Oren Kolodny ◽

Joseph Y. Halpern ◽

Luca Onnis ◽

Shimon Edelman

Keyword(s):

Working Memory ◽

Language Acquisition ◽

Recent Theory ◽

Cognitive Mechanisms ◽

Selection Pressures ◽

Biological Trait ◽

Memory Bottleneck

AbstractAs a highly consequential biological trait, a memory “bottleneck” cannot escape selection pressures. It must therefore co-evolve with other cognitive mechanisms rather than act as an independent constraint. Recent theory and an implemented model of language acquisition suggest that a limit on working memory may evolve to help learning. Furthermore, it need not hamper the use of language for communication.

Download Full-text

The sense of obligation is culturally modulated

Behavioral and Brain Sciences ◽

10.1017/s0140525x19002371 ◽

2020 ◽

Vol 43 ◽

Author(s):

Andrea Bender

Keyword(s):

Cultural Studies ◽

Cross Cultural ◽

Human Populations ◽

Cultural Group ◽

Target Article ◽

Sense Of Obligation ◽

Cross Cultural Studies

Abstract Tomasello argues in the target article that, in generalizing the concrete obligations originating from interdependent collaboration to one's entire cultural group, humans become “ultra-cooperators.” But are all human populations cooperative in similar ways? Based on cross-cultural studies and my own fieldwork in Polynesia, I argue that cooperation varies along several dimensions, and that the underlying sense of obligation is culturally modulated.

Download Full-text

Self-Injurious Behavior vs. Nonsuicidal Self-Injury

Crisis ◽

10.1027/0227-5910/a000127 ◽

2012 ◽

Vol 33 (2) ◽

pp. 106-112 ◽

Cited By ~ 3

Author(s):

Christopher M. Bloom ◽

Shareen Holly ◽

Adam M. P. Miller

Keyword(s):

Positive Reinforcement ◽

Empirical Investigation ◽

High Stress ◽

Animal Research ◽

Stress Conditions ◽

Human Populations ◽

Pharmacological Interventions ◽

Self Injury ◽

Cns Stimulant ◽

Nonsuicidal Self Injury

Background: Historically, the field of self-injury has distinguished between the behaviors exhibited among individuals with a developmental disability (self-injurious behaviors; SIB) and those present within a normative population (nonsuicidal self-injury; NSSI),which typically result as a response to perceived stress. More recently, however, conclusions about NSSI have been drawn from lines of animal research aimed at examining the neurobiological mechanisms of SIB. Despite some functional similarity between SIB and NSSI, no empirical investigation has provided precedent for the application of SIB-targeted animal research as justification for pharmacological interventions in populations demonstrating NSSI. Aims: The present study examined this question directly, by simulating an animal model of SIB in rodents injected with pemoline and systematically manipulating stress conditions in order to monitor rates of self-injury. Methods: Sham controls and experimental animals injected with pemoline (200 mg/kg) were assigned to either a low stress (discriminated positive reinforcement) or high stress (discriminated avoidance) group and compared on the dependent measures of self-inflicted injury prevalence and severity. Results: The manipulation of stress conditions did not impact the rate of self-injury demonstrated by the rats. The results do not support a model of stress-induced SIB in rodents. Conclusions: Current findings provide evidence for caution in the development of pharmacotherapies of NSSI in human populations based on CNS stimulant models. Theoretical implications are discussed with respect to antecedent factors such as preinjury arousal level and environmental stress.

Download Full-text