**4. Results**

## *4.1. Description of Cerebellar Asymmetries*

Results of the descriptive statistics and bootstrapped *t*-test were shown in Table 4. No significant asymmetry was observed among the four measurements within *H. erectus* and *H. neanderthalensis*. However, the result of Neanderthals should be taken with caution as only a small sample size is available. Within the *H. sapiens* group, only the cerebellar length is significantly larger on the left side.

**Table 4.** Descriptive results of measurements and bootstrapped *t*-test.


\* Significance level is lower than 0.05.

Together with the boxplot (as illustrated in Figure 2), a preliminary evolutionary change of the cerebellar metrics can be summarized. There is an obvious growth of the cerebellar length and cerebellar height for Neanderthals and modern humans over the *H. erectus*. However, the sagittal orientation of the cerebellar is wider for Neanderthals and *H. erectus* while this value is quite small for modern humans. For the horizontal orientation, Neanderthals and modern humans are relatively steep while it is rather flat in *H. erectus*. The CVs of horizontal orientation are high in the process of error evaluation and may contribute to within-group variation here.

**Figure 2.** Boxplot of cerebellar metrics.
