Smarter people are (a bit) more symmetrical: A meta-analysis of the relationship between intelligence and fluctuating asymmetry

Individual differences in general mental ability (g) have important implications across multiple disciplines. Research suggests that the variance in g may be due to a general fitness factor. If this is the case, a relationship should exist between g and other reliable indicators of fitness. Some empirical results indicate a relationship between g and fluctuating asymmetry. However, there have been inconsistencies in the results, some of which may be due to random sampling error, and some of which may be due to moderating variables, publication bias, and methodological issues. To help clarify the literature, a meta-analysis was conducted on the relationship between g and fluctuating asymmetry. Based on 14 samples across 1871 people, estimates of the population correlation ranged from −.12 to −.20. There was a difference in the magnitude of the correlation between published studies and unpublished studies with published studies showing larger magnitude negative correlations and unpublished studies yielding results closer to zero. The implications for our understanding of g and its relationship with fluctuating asymmetry are discussed.