Table 2.
Crown extension rates for human, chimpanzee, and Neanderthal first molars
| Cusp* | Taxon | Mean | N | Range |
|---|---|---|---|---|
| U mp | Homo sapiens | 5.82 | 14 | 5.28–6.66 |
| Pan troglodytes | 7.77 | 3 | 7.66–7.90 | |
| Homo neanderthalensis | 7.60 | 1 | — | |
| U mb | Homo sapiens | 5.87 | 13 | 4.68–7.47 |
| Pan troglodytes | 6.93 | 3 | 5.81–7.61 | |
| Homo neanderthalensis | 8.47† | 1 | — | |
| L mb | Homo sapiens | 6.61 | 18 | 5.35–7.42 |
| Pan troglodytes | 7.94 | 5 | 7.07–8.88 | |
| Homo neanderthalensis | 7.70‡ | 1 | — | |
| L ml | Homo sapiens | 6.30 | 27 | 5.07–7.27 |
| Pan troglodytes | 8.82 | 5 | 8.00–9.43 | |
| Homo neanderthalensis | 7.68‡ | 1 | — |
Values represent the length of the enamel–dentine junction (EDJ) divided by the cusp-specific crown formation time, followed by the sample size of each cusp (N) and the range (minimum to maximum values).
*U, maxillary; mp, mesiopalatal cusp (protocone); mb, mesiobuccal cusp (paracone); L, mandibular; mb, mesiobuccal cusp (protoconid); ml, mesiolingual cusp (metaconid).
†Estimated using minor reconstruction of dentine horn tip and prenatal enamel equal to mesiopalatal cusp.
‡Calculated using mCT data to virtually section tooth (optimizing for mesial EDJ length); cusp-specific EDJ length was divided by formation times reported in ref. 8 for each cusp.