Acknowledgments Support for this work included grants from the National Heart, Lung, and Blood Institute to Dr. Lawrence Sweet (R01HL084178) and Dr. Xiaomeng Xu (2T32HL076134-06). Conflict of Interest None declared.
How is handedness defined? Commonly, handedness means hand preference. For most people, the preferred hand is the hand which is most efficient to perform specific manual dexterity tasks (e.g., writing, manipulating objects or tools, etc.). In the Inhibitors,research,lifescience,medical present study, in line with a previously proposed concept (e.g., Hopkins et al. 1992; Triggs et al. 2000),

we propose to emphasize the distinction between two hand attributes: hand preference and hand dominance. The hand of preference is defined as the hand with which subjects prefer to work on a specific task, instinctively and without concern whether this hand is actually the most efficient one. In bimanual tasks for instance (e.g., tapping a nail with a hammer, knitting, eating with a fork, and a knife, etc.), the preferred hand is the hand Inhibitors,research,lifescience,medical which executes the most complex action or the manipulative role, whereas the nonpreferred hand acts mainly as postural support. In the above mentioned bimanual tasks, they need to be learned, whereas other bimanual tasks are more instinctive and they are also observed in nonhuman primates (e.g., peeling a fruit, Inhibitors,research,lifescience,medical cracking a nut with a stone, etc.). In contrast Inhibitors,research,lifescience,medical to hand

preference, hand dominance refers to the hand which shows the best efficiency to perform a particular unimanual action (Serrien et al. 2006), thus reflecting an intermanual difference of motor performance. The general aim of the present study was to assess separately hand preference and hand dominance in eight adult long-tailed macaque monkeys (Macaca fascicularis) and in 20 young adult

human subjects. Inhibitors,research,lifescience,medical Population-level right-handedness (preference for the right hand) was considered for a long time as a feature of human being (Raymond et al. 1996). During the last 20 years, several studies demonstrated that handedness for specific manual tasks is also present in nonhuman primates, from prosimians to great apes (e.g., Masataka 1989; Ward et al. 1990, Cediranib (AZD2171) 1993; Fagot and Vauclair 1991; Spinozzi et al. 1998; Lacreuse et al. 1999; Hopkins et al. 2011). Whereas 90% of AZD4547 humans are right-handed (Coren and Porac 1977; Raymond and Pontier 2004), the percentage and the direction of the lateralization vary among the nonhuman primates (see e.g., Papademetriou et al. 2005; mainly for reaching tasks). Concerning the great apes, a recent study by Hopkins et al. (2011) showed population right-handedness, except for Orangutans, which tend to use preferentially the left hand. These results are consistent with other studies (Lacreuse et al. 1999; Wesley et al. 2001; Hopkins et al. 2002, 2003, 2004, 2005; Sherwood et al. 2007).