 Evolution of knuckle-walking There are competing hypotheses as to how knuckle-walking evolved as a form of locomotion, stemming from comparisons between African apes.
<clarity>  Evolution of knuckle-walking There are competing hypotheses as to how knuckle-walking evolved as a form of locomotion, stemming from comparisons between African apes.
 Evolution of knuckle-walking Competing hypotheses are given as to how knuckle-walking evolved as a form of locomotion, stemming from comparisons between African apes.