Reading a fossil skull
Palaeontologists compare skulls of apes, early hominids and modern humans. Key features and the trend towards modern humans:
| Feature | African apes | Modern humans | What it shows |
|---|
| Foramen magnum | Towards the back | Central, under the skull | Head balanced on an upright spine: bipedalism |
| Brow ridges | Prominent | Reduced | Change in face and skull shape |
| Jaw (prognathism) | Protruding | Flat face | Smaller jaw and teeth, softer or cooked diet |
| Canines | Large, with gaps (diastema) | Small, no gap | Change in diet and behaviour |
| Cranium | Small, low | Large, rounded | Larger brain |
Brain volume across hominids
| Genus / species | Approximate brain volume |
|---|
| Australopithecus (e.g. A. africanus) | 400–500 cm³ |
| Homo habilis | 550–680 cm³ |
| Homo erectus | 750–1 250 cm³ |
| Homo sapiens | about 1 350 cm³ |
The general trend is an increase in brain volume, linked to tool use, more complex behaviour and diet. The trend is not a straight line: some later species, such as Homo naledi, had small brains.
South African sites
- Taung (1924) — the Taung Child, the first Australopithecus africanus described, by Raymond Dart.
- Sterkfontein — “Mrs Ples” (A. africanus, 1947) and “Little Foot”, a nearly complete australopithecine skeleton.
- Malapa (2008) — Australopithecus sediba, with a mix of ape-like and human-like features.
- Rising Star cave (found 2013, named 2015) — Homo naledi: a small brain (estimates vary, roughly 450–600 cm³) but human-like hands and feet. It lived about 236 000–335 000 years ago, overlapping in time with early Homo sapiens.
These sites are part of the Cradle of Humankind World Heritage Site and support the Out of Africa hypothesis, along with mitochondrial DNA evidence.
Evidence of behaviour: Blombos and Wonderwerk
- Blombos Cave (Southern Cape coast) — engraved ochre pieces and perforated shell beads about 75 000 years old, and an ochre-processing kit about 100 000 years old. They show early symbolic behaviour in Homo sapiens, such as decoration and possibly communication through symbols.
- Wonderwerk Cave (Northern Cape) — burnt bone and plant ash about one million years old, among the earliest evidence of controlled fire, associated with early Homo.
Why caves preserve evidence: they are sheltered from wind and rain, sediments build up in layers that can be dated, and the stable conditions slow decay. Excavated caves are often closed to the public to protect deposits that are still being studied.
Worked example: comparing two skulls
✏️ Exam-style comparison
1Skull A has a central foramen magnum, small canines and a large rounded cranium; skull B has the foramen magnum further back, a protruding jaw and prominent brow ridges.
2Skull A is more likely Homo; skull B is more likely Australopithecus.
3In a table of differences, compare the same feature in both columns, for example “Brow ridges: reduced in A, prominent in B”.