The role of testosterone in risk-taking behaviour

• Applicant: Dr. Ines Fürtbauer
• Subject Area: Sensory and Behavioural Biology
• Term: from 2013 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 246718376

Virtually every decision in life bears risk. However, individuals vary in their risk-taking propensity. Research has shown that risk-taking is partly hard-wired by our genes. Yet, underlying proximate mechanisms must be examined in order to specify the intermediate pathway linking our genes to our behaviour. The steroid hormone testosterone (T) has been identified as one potential pathway. Research on humans suggests that higher T levels are associated with greater economic and health risk-taking; however, drawing conclusions about causality from such studies is impossible because T levels are necessarily based on single-point hormone samples, studies often only focus on one sex, and confounding factors are difficult to control. Therefore, to more thoroughly study the potential causal link between T and risk-taking, we need to look to suitable animal models. I will test the hypothesis that T levels underlie individual variation in risk-taking behaviour in the model organism Gasterosteus aculeatus, a small, freshwater teleost fish. Using a three-step approach and a natural experiment (in breeding condition T is naturally increased in both sexes), I aim to investigate between- and within-individual differences and temporal consistency in individual risk-taking and waterborne T profiles. Hormone and behavioural data will be collected from n=90 individually marked male and female subjects. In fish, free steroids diffuse from the bloodstream into the water through the gills. Confining a fish to a known volume of water for a known period of time, one can extract these steroids and quantify their concentration. 1350 water hormone samples will be collected and analysed for immunoreactive T, following previously described and validated procedures. Four standard behavioural experiments focussing on exploratory and anti-predatory contexts will be conducted, i.e. I will determine to what extent individuals take risks and explore a novel environment and a novel object in a familiar environment, and investigate the subjects risk propensity after a simulated aerial predator attack, and exposure to a live predator. Fish movements will be video-taped, and behavioural measures will be extracted from videos and used to assess risk-taking profiles. Finally, using multivariate methods, hormones and behaviour will be integrated in order to test the overall hypothesis that basal T underlies risk-taking behaviour. This innovative and integrative study will, for the first time, examine the potential causal relationship between T and risk-taking in a quantitative and systematic manner, and thus, is a crucial step in understanding the proximate mechanisms underlying individual variation in risk propensity. The project will generate clear and testable predictions concerning the causes and consequences of variability in risky decision-making at the level of individuals, groups, and populations.

• DFG Programme: Research Fellowships
• International Connection: United Kingdom
• Host: Professor Andrew King, Ph.D.