Pre-cleaning of hair is not beneficial in LA-ICP-MS studies of chronic metal exposure.

Chronic exposure to toxic metals is a serious global health concern. However, population-wide biomonitoring is costly and carries several sampling constraints. Though hair sampling can be a useful way to assess environmental exposure, external contamination is a long-standing concern, and a pre-cleaning step prior to metal quantification has long been recommended despite a lack of evidence for its efficacy. In this study, we quantified the spatial distribution of 16 elements in unwashed human hair samples using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), then tested how two common pre-cleaning treatments (Triton-ethanol, Triton-nitric acid) affected metal content in external and interior layers of hair using LA-ICP-MS. We show that elements differ in their spatial distribution across hair and that pre-cleaning is not consistent in its effect on element concentrations and decreases interior concentrations of some elements. We demonstrate that differences among individuals can be quantified reliably with LA-ICP-MS analysis of interior concentrations of unwashed hair. Our study tests the widespread notion that pre-cleaning is essential in analyses of hair for environmental exposure to metals, and examines the benefits of a unified approach to analysis of metals in hair using LA-ICP-MS.

Skill not athleticism predicts individual variation in match performance of soccer players.

Just as evolutionary biologists endeavour to link phenotypes to fitness, sport scientists try to identify traits that determine athlete success. Both disciplines would benefit from collaboration, and to illustrate this, we used an analytical approach common to evolutionary biology to isolate the phenotypes that promote success in soccer, a complex activity of humans played in nearly every modern society. Using path analysis, we quantified the relationships among morphology, balance, skill, athleticism and performance of soccer players. We focused on performance in two complex motor activities: a simple game of soccer tennis (1 on 1), and a standard soccer match (11 on 11). In both contests, players with greater skill and balance were more likely to perform better. However, maximal athletic ability was not associated with success in a game. A social network analysis revealed that skill also predicted movement. The relationships between phenotypes and success during individual and team sports have potential implications for how selection acts on these phenotypes, in humans and other species, and thus should ultimately interest evolutionary biologists. Hence, we propose a field of evolutionary sports science that lies at the nexus of evolutionary biology and sports science. This would allow biologists to take advantage of the staggering quantity of data on performance in sporting events to answer evolutionary questions that are more difficult to answer for other species. In return, sports scientists could benefit from the theoretical framework developed to study natural selection in non-human species.

Daylight saving time can decrease the frequency of wildlife-vehicle collisions.

Daylight saving time (DST) could reduce collisions with wildlife by changing the timing of commuter traffic relative to the behaviour of nocturnal animals. To test this idea, we tracked wild koalas (Phascolarctos cinereus) in southeast Queensland, where koalas have declined by 80% in the last 20 years, and compared their movements with traffic patterns along roads where they are often killed. Using a simple model, we found that DST could decrease collisions with koalas by 8% on weekdays and 11% at weekends, simply by shifting the timing of traffic relative to darkness. Wildlife conservation and road safety should become part of the debate on DST.

Receivers limit the prevalence of deception in humans: evidence from diving behaviour in soccer players.

Deception remains a hotly debated topic in evolutionary and behavioural research. Our understanding of what impedes or facilitates the use and detection of deceptive signals in humans is still largely limited to studies of verbal deception under laboratory conditions. Recent theoretical models of non-human behaviour have suggested that the potential outcome for deceivers and the ability of receivers to discriminate signals can effectively maintain their honesty. In this paper, we empirically test these predictions in a real-world case of human deception, simulation in soccer. In support of theoretical predictions in signalling theory, we show that cost-free deceit by soccer players decreases as the potential outcome for the signaller becomes more costly. We further show that the ability of receivers (referees) to detect deceptive signals may limit the prevalence of deception by soccer players. Our study provides empirical support to recent theoretical models in signalling theory, and identifies conditions that may facilitate human deception and hinder its detection.