Figure 2. Relative length of the thumb in H. naledi Hand 1.

Relative length of the thumb (ray 1, total length of the first metacarpal and first proximal phalanx) and third ray (total length of the third metacarpal and third proximal and intermediate phalanges) within the same individual, in all taxa except A. afarensis (*), for which the ratio is one potential estimate of hand proportions derived from multiple individuals7,8,10. (a) A box-and-whisker plot, where the box represents the 25th and 75th percentiles, the centre line represents the median and the whiskers represent the non-outlier range, of ray 1 to ray 3 length (as a percentage) demonstrates that Hand 1 has a relatively longer thumb than all other hominins, apart from A. sediba, and falls within the upper range of variation in modern human males only. (b) Linear regression of ray 1 length to ray 3 length, with regression line fit to modern humans (males and females combined), shows that Hand 1 (DH1) has a relatively long thumb for its small hand size, falling on the edge of modern human variation. Male and female modern human sample comprises African (n=31), Nubian Egyptian (n=11) and small-bodied Khoisan (n=25) individuals. Data for Shanidar 4 are derived from ref. 17.