Physical competition increases testosterone among Amazonian forager-horticulturalists: a test of the 'challenge hypothesis'

Proc Biol Sci. 2012 Jul 22;279(1739):2907-12. doi: 10.1098/rspb.2012.0455. Epub 2012 Mar 28.


The challenge hypothesis posits that acute increases in testosterone (T) during male-male competition enhance performance and survivability while limiting the physiological costs of consistently high T. Human challenge hypothesis research focuses on young men in industrial populations, who have higher baseline T levels than men in subsistence populations. We tested whether the Tsimane, pathogenically stressed forager-horticulturalists of the Bolivian Amazon, would express acute T increases in response to physical competition. Saliva was collected from 88 Tsimane men (aged 16-59 years) before and after a competitive soccer match. Tsimane men had significantly lower baseline levels of T (β = -0.41, p < 0.001) when compared with age-matched United States (US) males. Linear mixed-effects models were used to establish that T increased significantly immediately following competition (β = 0.23, p < 0.001), remaining high 1 h later (β = 0.09, p = 0.007); equivalent to 30.1 and 15.5 per cent increases in T, respectively. We did not find larger increases in T among winners (p = 0.412), although T increases were positively associated with self-rated performance (β = 9.07, p = 0.004). These results suggest that despite lower levels of T than US males, Tsimane males exhibit acute increases in T at the same relative magnitude reported by studies in industrialized settings, with larger increases in T for those who report better individual performance.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Bolivia
  • Ecosystem
  • Human Activities
  • Humans
  • Industry
  • Linear Models
  • Male
  • Middle Aged
  • Models, Biological
  • Saliva / chemistry*
  • Soccer
  • Stress, Physiological
  • Testosterone / chemistry*
  • Testosterone / physiology*
  • United States
  • Young Adult


  • Testosterone