Figure 1.

A preliminary dataset including 34 species (Artiodactyla: n = 5, Carnivora: n = 13, Cetacea: n = 1, Chiroptera: n = 2, Primates: n = 13) suggests that most habitual tool users do seem to acquire their skills relatively late during ontogeny compared with other species that were not qualified as habitual tool users by Shumaker et al. [1] (although differences are not significant). Legend numbers refer to tool-use category as displayed on the x-axis. Sea otters appear to be an outlier among the habitual tool users (acquiring their tool use relatively fast); whereas spotted hyaenas and wolves appear to be outliers among the non-routine tool users because they acquire their skills (i.e. hunting skills) relatively late. Data on age at skill competence (ASC) and age at first reproduction (AFR) were taken from Schuppli et al. [55]. Data on routine tool use come from Shumaker et al. [1].