Fluctuating asymmetry, a marker of poor growth quality, is associated with adult male metabolic rate

Daniel P Longman,James Cracknell,Nathan Thompson,Sakura Oyama,Jonathan C K Wells,Dan Gordon,Jay T Stock

doi:10.1002/ajpa.24276

Abstract

Life history theory, a branch of evolutionary theory, predicts the existence of trade-offs in energetic allocation between competing physiological functions. The core metabolic cost of self-maintenance, measured by resting metabolic rate (RMR), represents a large component of human daily energy expenditure. Despite strong selective pressures for energetic frugality and high observed interindividual variation in RMR, the link between RMR and energetic allocation to life-history traits remains understudied in humans. In a sample of 105 (m = 57, f = 48), we investigated the relationship between adult RMR and investment in growth quality, as measured by fluctuating asymmetry (FA). Measurement of RMR and FA in university rowers revealed a significant positive correlation amongst males (n = 57, r = 0.344, p = 0.005, 1-tailed; standardized 95% CI, 0.090 to 0.598). Convincing evidence for a correlation among females was not found (n = 48, r = 0.142, p = 0.169, 1-tailed, standardized 95% CI, -0.152 to 0.435). The data suggest that low-quality asymmetrical growth is associated with later-life metabolic inefficiencies in males. Energetic investment in processes (likely concerning the stress-response) unrelated to growth during childhood may thereby trade-off against adult metabolic efficiency. We suggest that the presence of a relationship between RMR and FA in males but not females may be explained by the additional metabolic strain associated with larger body size and increased male muscularity, which may amplify the inefficiencies arising from low-quality growth.

Highlights

As previously mentioned, there is evidence relating environmental stressors to increased fluctuating asymmetry (FA), we propose that it is unlikely that a high resting metabolic rate (RMR) in early life would act to constrain the quality of growth
Regression analysis revealed no significant correlation between RMR and composite FA (CFA) (n = 48, r = 0.142, r2 = 0.020, p = 0.169, 1-tailed; standardized 95% CI, −0.152 to 0.435)
This study identified a significant positive correlation between male RMR and fluctuating asymmetry (n = 57, r = 0.344, p = 0.009, 1-tailed; standardized 95% CI, 0.090 to 0.598)

Summary

| MATERIALS AND METHODS

The participants were 57 male and 48 female student rowers from the University of Cambridge, and testing being carried out in Cambridge, UK. RMR was measured in accordance following standard procedure (Compher et al, 2006) using a Cortex Metalyzer 3b under controlled conditions (29% humidity and 18C). Seven bilaterally symmetrical traits were selected given their previous use in the literature, high repeatability, and resistance to the effects of mechanical loading. These traits were: lengths of all four fingers, wrist width, ankle width, and foot length.

| RESULTS

Findings

| DISCUSSION