title: Digit ratio (2D:4D), testosterone, cortisol, aggression, personality and hand-grip strength: Evidence for prenatal effects on strength.
abstract: Digit ratio (2D:4D) is a putative marker for prenatal testosterone and is correlated with performance in many sports. Low 2D:4D has been linked to strength but the evidence is mixed and strength is also influenced by mass, testosterone, and behavioural factors. It has been hypothesised that the 2D:4D-strength correlation may be strongest in challenge conditions when short-term changes occur in steroid hormones.
  
  
  
  We tested this suggestion in men.
  
  
  
  We used a cross-over study design with a challenge (an aggressive video of rugby tackles) and control (a blank screen) condition.
  
  
  
  89 healthy men.
  
  
  
  Finger lengths (2nd and 4th for both hands), hand-grip strength (HGS), testosterone (T), cortisol (C), aggression (Buss-Perry Aggression Questionnaire) and personality type (Ten Item Personality Measure). In both conditions participants provided saliva samples (for hormone assays).
  
  
  
  In the challenge condition there was a highly significant increase in HGS, and modest changes in T, physical aggression and emotional stability. HGS correlated negatively with left hand 2D:4D. In a multiple regression, left hand 2D:4D was negatively related to HGS and emotional stability was positively related to HGS. In the control condition HGS was not correlated with 2D:4D. In a multiple regression, BMI, physical aggression, and emotional stability were significantly related to HGS.
  
  
  
  2D:4D is a negative correlate of strength in challenge situations. This finding may in part explain associations between 2D:4D and sports performance.
authors.affiliation: Department of Physiology, University of Paraná, Curitiba, Brazil.
authors.forename: Evaldo
authors.initials: E
authors.lastname: Ribeiro
authors.affiliation: Department of Psychology, Northumbria University, Newcastle-upon-Tyne, UK.
authors.forename: Nick
authors.initials: N
authors.lastname: Neave
authors.affiliation: Department of Physiology, University of Paraná, Curitiba, Brazil.
authors.forename: Rosana Nogueiro
authors.initials: RN
authors.lastname: Morais
authors.affiliation: Applied Sports, Technology, Exercise and Medicine (A-STEM), Swansea University, Swansea, UK.
authors.forename: Liam
authors.initials: L
authors.lastname: Kilduff
authors.affiliation: Sport and Exercise Sciences, Glyndwr University, Wrexham, UK.
authors.forename: Suzan R
authors.initials: SR
authors.lastname: Taylor
authors.affiliation: Department of Cross-Cultural Psychology and Human Ethology, Institute of Ethnology and Anthropology, Russian Academy of Sciences and Russian State University of Humanities, Moscow, Russia.
authors.forename: Marina
authors.initials: M
authors.lastname: Butovskaya
authors.affiliation: Institute of Psychology, University of Göttingen, Göttingen, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Fink
authors.affiliation: Applied Sports, Technology, Exercise and Medicine (A-STEM), Swansea University, Swansea, UK. Electronic address: j.manning@swansea.ac.uk.
authors.forename: John T
authors.initials: JT
authors.lastname: Manning
mesh_terms: D000293:Adolescent; D000328:Adult; D000374:Aggression / Q000502:physiology*; D054874:Athletic Performance; D018592:Cross-Over Studies; D047109:Fetal Development / Q000502:physiology; D005385:Fingers / Q000033:anatomy & histology*; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D008297:Male; D010551:Personality / Q000502:physiology*; D012463:Saliva / Q000737:chemistry; D012727:Sex Characteristics; D013739:Testosterone / Q000032:analysis*; D006113:United Kingdom; D055815:Young Adult
chemical_list: D013739:Testosterone; D006854:Hydrocortisone
keywords: Aggression; Digit ratio; Hand-grip strength; Testosterone