On the other hand: Current issues in and meta-analysis of the behavioral laterality of hand function in nonhuman primates
Article first published online: 6 DEC 1998
Copyright © 1997 Wiley-Liss, Inc.
American Journal of Physical Anthropology
Supplement: Yearbook of Physical Anthropology
Volume 104, Issue Supplement 25, pages 201–232, 1997
How to Cite
McGrew, W. C. and Marchant, L. F. (1997), On the other hand: Current issues in and meta-analysis of the behavioral laterality of hand function in nonhuman primates. Am. J. Phys. Anthropol., 104: 201–232. doi: 10.1002/(SICI)1096-8644(1997)25+<201::AID-AJPA8>3.0.CO;2-6
- Issue published online: 6 DEC 1998
- Article first published online: 6 DEC 1998
- hand preference;
The last decade has seen a resurgence of interest in laterality of function in primates, especially in hand use as it links to handedness and language in Homo sapiens. Manual lateralization of behavior in humans reflects asymmetry in cerebral structure, which must have evolved from nonhuman progenitors. To what extent is hand function lateralized in our nearest living relations? First, we address current issues of theory and methodology: statistics, measurement, variables, setting, sensory modality, and sample size. Specific topics include preference vs. performance, posture, bimanuality, inheritance, and arm asymmetry. We categorize the published literature in a descriptive, classificatory framework of five levels that range from Level 1, ambilaterality, to Level 5, human-like handedness. In a meta-analysis we put 241 published data-sets to a methodological test of seven criteria and code the 48 survivors onto the levels framework, by taxonomic grouping (prosimian, New World monkey, Old World monkey, ape, chimpanzee). Primates at Level 1 are mostly wild or naturalistic populations performing spontaneous species-typical behavior patterns. Most primates are at Levels 2 and 3, that is, individually lateralized to either side, especially on complex, demanding or practiced tasks, usually as devised in captive settings. Only chimpanzees show signs of population-level bias (Levels 4 and 5) to the right, but only in captivity and only incompletely. We conclude that nonhuman primate hand function has not been shown to be lateralized at the species level—it is not the norm for any species, task, or setting, and so offers no easy model for the evolution of human handedness. Yrbk Phys Anthropol 40:201–232, 1997. © 1997 Wiley-Liss, Inc.