Fig. 1: Box and whisker plots showing the distribution of δ^44/42Ca values (in ‰) between the various non-hominin and hominin primates analyzed in this study as well as some modern representatives (Papio anubis, Theropithecus gelada, and Gorilla gorilla gorilla).

Note the ⁴⁴Ca-enriched isotope values of Paranthropus boisei in comparison to other groups. The boxes represent the first and third quartiles with the medians as horizontal lines. The lower and upper whiskers represent 1.5 * the interquartile range (numbers of biologically independent samples per group: n = 9 for Colobini; n = 5 for Papio anubis; n = 4 for Parapapio sp.; n = 2 for Theropithecus gelada; n = 7 for Theropithecus brumpti; n = 8 for Theropithecus oswaldi; n = 4 for Gorilla gorilla gorilla; n = 8 for Australopithecus anamensis; n = 5 for Kenyanthropus platyops; n = 8 for Paranthropus boisei; n = 13 for early Homo). Welch’s one-way ANOVA and Kruskal–Wallis tests show significant differences of average means (Welch’s one-way ANOVA on all groups except the two T. gelada individuals: 10 groups with a total of 71 biologically independent individual samples, p value < 10⁻⁴, F = 11.7, df = 9; Kruskal–Wallis on all groups: 11 groups with a total of 73 biologically independent individual samples, p value = 0.0005, df = 10). δ^44/42Ca values are expressed both against ICP Ca Lyon (left) and SRM915a (right). Source data are provided as a Source Data file.