Asymmetries in ear movements and eyebrow raising in men and women and right- and left-handers.

The abilities to move ears and eyebrows were examined in 442 subjects (204 men, 238 women) categorized as right-handed (n = 382) and left-handed (n = 60, including mixed and ambidextrous-handed subjects). Approximately 22% could move one or the other ear and about 18% could move both ears simultaneously, but significantly more men could move both ears simultaneously. Significantly more men than women were able to move both the left and right eyebrow and the left ear. No differences were observed between right- and left-handers. Significant contingency correlations were observed between raising eyebrows and moving ears. Results are discussed with reference to a possible left ear-right hemisphere advantage for localising environmental sounds, primitive ear-moving abilities no longer functional in modern humans, and epiphenomenal by-products of other adaptive sex differences.