Why Are Most Humans Right-Handed? The Modified Fighting Hypothesis

Matz Larsson, Astrid Schepman, Paul Rodway

Research output: Contribution to journalReview articlepeer-review

Abstract

Humans show a population-level preference for using the right hand. The fighting hypothesis is an influential theory that suggests that left-handedness persists because its rarity provides a surprise advantage in fighting interactions, and that left-handedness is less frequent because it has a health cost. However, evidence for the health cost of left-handedness is unsubstantiated, leaving the greater frequency of right-handers unexplained. Research indicates that homicide may have been common in early hominins. We propose that the hand used to hold a weapon by early hominins could have influenced the outcome of a fight, due to the location of the heart and aorta. A left-handed unilateral grip exposes the more vulnerable left hemithorax towards an opponent, whereas a right-hand unilateral grip exposes the less vulnerable right hemithorax. Consequently, right-handed early ancestors, with a preference for using the right forelimb in combat, may have had a lower risk of a mortal wound, and a fighting advantage. This would explain their greater frequency. In accordance with the original fighting hypothesis, we also suggest that left-handed fighters have a surprise advantage when they are rare, explaining their persistence. We discuss evidence for the modified fighting hypothesis, its predictions, and ways to test the theory.

Original languageEnglish
Article number940
JournalSymmetry
Volume15
Issue number4
DOIs
Publication statusPublished - 2023 Apr

Subject classification (UKÄ)

  • Psychology (excluding Applied Psychology)

Free keywords

  • ancestor
  • hand preference
  • lateralized function
  • tools
  • warfare

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