Testosterone histories from tusks reveal woolly mammoth musth episodes.

Hormones in biological media reveal endocrine activity related to development, reproduction, disease and stress on different timescales1. Serum provides immediate circulating concentrations2, whereas various tissues record steroid hormones accumulated over time3,4. Hormones have been studied in keratin, bones and teeth in modern5-8 and ancient contexts9-12; however, the biological significance of such records is subject to ongoing debate10,13-16, and the utility of tooth-associated hormones has not previously been demonstrated. Here we use liquid chromatography with tandem mass spectrometry paired with fine-scale serial sampling to measure steroid hormone concentrations in modern and fossil tusk dentin. An adult male African elephant (Loxodonta africana) tusk shows periodic increases in testosterone that reveal episodes of musth17-19, an annually recurring period of behavioural and physiological changes that enhance mating success20-23. Parallel assessments of a male woolly mammoth (Mammuthus primigenius) tusk show that mammoths also experienced musth. These results set the stage for wide-ranging studies using steroids preserved in dentin to investigate development, reproduction and stress in modern and extinct mammals. Because dentin grows by apposition, resists degradation, and often contains growth lines, teeth have advantages over other tissues that are used as records of endocrine data. Given the low mass of dentin powder required for analytical precision, we anticipate dentin-hormone studies to extend to smaller animals. Thus, in addition to broad applications in zoology and palaeontology, tooth hormone records could support medical, forensic, veterinary and archaeological studies.

Trust in scientists and rates of noncompliance with a fisheries rule in the Brazilian Pantanal.

Natural resource rules exist to control resources and the people that interact with them. These rules often fail because people do not comply with them. Decisions to comply with natural resource rules often are based on attitudes about legitimacy of rules and the perceived risks of breaking rules. Trust in agencies promulgating rules in part may determine perceptions of legitimacy of the rule, and in turn depends on individuals' trust in different agency actors. The purpose of this research is to explore the relationship between fishing rule noncompliance and trust in scientists, a key group within management agencies. We interviewed 41 individuals in one rural fishing community in the Brazilian Pantanal from April to August, 2016, to assess (1) noncompliance rates, (2) noncompliance-related attitudes, and (3) the relationship between trust in scientists and noncompliance decisions in the region. We found that among study participants, noncompliance was common and overt. Trust in scientists performing research in the region was the best predictor of noncompliance rate with a fishing rule (nonparametric rank correlation ρ = -0.717; Probit model pseudo-R2 = 0.241). Baseline data from this research may help inform future interventions to minimize IUU fishing and protect the Pantanal fishery. Although our results are specific to one community in the Pantanal, trust in scientists is potentially an important factor for compliance decisions in similar situations around the world. These results build not only on compliance theory but also speak to the important role that many scientists play in rural areas where they conduct their research.