Ancient proteins from Australopithecus africanus have, for the first time, revealed the biological sex of an individual who lived in southern Africa millions of years ago. The 2025 study in the South African Journal of Science (Madupe et al.) shows how molecular methods now sit beside classical fossil morphology in human evolution.
Source: Madupe et al., South African Journal of Science, 7 February 2025.
How Palaeoproteomics Supports Fossil Study
- Tooth enamel: Sts 63, Sterkfontein
- Preserved enamel proteins
- Amelogenin analysis
- Biological sex inference: male
- Read alongside morphology
One specimen, one result. It adds to, and does not replace, classical fossil analysis.
The discovery
The team studied tooth enamel from specimen Sts 63, found at Sterkfontein in South Africa’s Cradle of Humankind. The fossil belongs to Member 4 of the cave deposits, which researchers usually date to roughly 3.5 to 2 million years ago. Tooth enamel is the hardest tissue in the body and shields proteins trapped inside it.
How the sex was read
DNA rarely survives in warm African fossils of this age, and beyond roughly 100,000 years it is hard to recover in most settings. Proteins last longer, which is why palaeoproteomics suits deep-time questions. The researchers looked at amelogenin, an enamel protein encoded on both the X and Y chromosomes. The Y version differs slightly from the X version. Finding the Y-linked variant in Sts 63 indicated a male individual.
The reasoning is simple. Enamel forms early in life and seals proteins inside a mineral shell, so the shell protects them from heat, water and microbes. Researchers can then match the peptides they recover from the shell to known protein sequences, and the presence or absence of the Y-linked form gives the answer.
Why it matters for physical anthropology
Researchers usually infer sex in fossil hominins from body size or bone shape, and both can mislead when the sample is small. A protein-based estimate gives an independent line of evidence. It also opens a route to ask whether size differences between males and females in Australopithecus were as large as some skeletal studies suggest. That question bears on social behaviour and mating systems, which are always debated for early hominins. Keep the limits in view, though: this is one tooth from one individual, and it speaks to sex, not to ancestry or evolutionary relationships.
The method is also less destructive and works in places where DNA is gone. For this reason, palaeoproteomics is a good candidate to appear in more questions on techniques in physical anthropology.
Where it sits in the wider story
Australopithecus africanus has been central to debates since Raymond Dart described the Taung Child in 1925. Later work on Sterkfontein fossils has asked how this species relates to other australopiths and to early Homo. The protein result does not settle that question. It adds a new kind of evidence to an old fossil record, which is why examiners may value it as an example of method rather than as a new phylogeny.
Cautions when writing the answer
Be careful with specimen details. Sts 63 comes from Sterkfontein. Homo naledi comes from the Rising Star cave system, a separate site. Quote ages as approximate ranges, because researchers have revised the dating of the Sterkfontein deposits more than once.
Using it in UPSC Mains
Use this under Paper I, Section 1.6(a) on the Australopithecines, and in answers on methods of studying fossils. A strong answer states the species, the site, the protein method and its limits in four or five lines.
Practise with the PYQ Australopithecus of South and East Africa and the Taung Baby (2023). More questions are in the Human Evolution and Primatology PYQs. For related reading, see New Species of Australopithecus and Hominin Diversity. The wider syllabus map is in the Anthropology Optional complete guide.