Morphological variability in chimpanzees
| Structure | Morphology | Left hemisphere | Right hemisphere | Total |
|---|---|---|---|---|
| Ipcs | One segment | 73.3% (22) | 80% (24) | 76.7% (46) |
| Two segments | 23.3% (7) | 16.7% (5) | 20% (12) | |
| Three segments | 3.3% (1) | 3.3% (1) | 3.3% (2) | |
| Ifs | One segment | 86.7% (26) | 80% (24) | 83.3% (50) |
| Two segments | 13.3% (4) | 20% (6) | 16.7% (10) | |
| Three segments | 0 | 0 | 0 | |
| Fos | One branch | 93.3% (28) | 93.3% (28) | 93.3% (56) |
| Two branches | 3.3% (1) | 6.7% (2) | 5% (3) | |
| Three branches | 3.3% (1) | 0 | 1.7% (1) |
fos, Fronto-orbital sulcus; ifs, inferior frontal sulcus; ipcs, inferior precentral sulcus.