**4. Discussion**

These findings sugges<sup>t</sup> greater R > L height asymmetry associated with no bridging pattern, moderate R > L height asymmetry for both R and L bridge patterns, smaller L < R height and width asymmetry with a L bridge pattern, and smaller R < L height asymmetry associated with right bridge pattern. Additionally, there was less uncertainty when predicting right and left siding using occipital lobe width rather than occipital lobe height, indicating width is a more reliable predictor than height. This has implications for the suitability of metrics chosen to examine an association with bridging patterns, especially if the sample is unknown where width provides more reliable predictors than height for future research in modelling occipital lobe bridging patterns and possible associations. Although we sugges<sup>t</sup> caution is warranted with the preliminary nature of these results, they also sugges<sup>t</sup> there is a component of asymmetry for chimpanzee occipital lobe bridge patterns, and that increasing width and not simply posterior movement (or reduced height) of the occipital lobe may play an important role in exposure of the occipital-parietal bridge during human evolution, which was unexpected. Future research will compare the size of the parietal to the occipital lobe in these same subjects.

**Author Contributions:** Conceptualization and methodology, R.H. and S.H.; measurements, G.B.; Statistical analyzes, review and editing, A.P.; original draft preparation, S.H.; review and editing, S.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding. **Data Availability Statement:** Measurements are contained in the article. MRI data can be obtained from the National Chimpanzee Brain Resource (https://www.chimpanzeebrain.org (accessed on 1 September 2021)).

**Acknowledgments:** The authors would like to thank Chet Sherwood & Aida Gomez-Robles for providing access to the data for these chimpanzees and Antoine Balzeau for inviting us to participate in this Special Issue.

**Conflicts of Interest:** The authors declare no conflict of interest.
