Anatomical evidence of one-sided forelimb dominance in the rhesus monkey

1. Differences in muscle and bone weight in the right and left forelimbs have been studied in twelve Rhesus monkeys. 2. There is anatomical evidence suggestive of one-sided limb dominance in nine animals, dominance being right sided in six animals and left sided in three animals. 3. The mean weights of all muscles and bones are greater on the dominant side except for the pectoralis major, the teres major and the clavicle. 4. The mean weight of the pectoralis major is greater on the non-dominant side and that of teres major and clavicle is equal on the two sides. The significance of these findings has been discussed in the light of observations in human adults and foetuses.