Ancient Proteins Reveal Sex of Australopithecus africanus

Source: South African Journal of Science | February 07, 2025

The Scientific Breakthrough

In a landmark discovery, scientists have identified the sex of a 3.5-million-year-old Australopithecus africanus individual using ancient protein analysis.
The study, led by Palesa P. Madupe and published in the South African Journal of Science, confirms that the fossil remains and tooth examined belonged to a male individual.

This marks the first successful sex determination of Australopithecus africanus using molecular evidence.

The Site: Sterkfontein Caves

The fossil was recovered from the Sterkfontein Caves, South Africa, a key component of the Cradle of Humankind, a UNESCO World Heritage Site.

The site is globally significant as it has yielded remains of at least six hominin species, including:
• Australopithecus africanus
• Homo naledi

Sterkfontein continues to play a central role in reconstructing early hominin evolution in Africa.

How the Sex Was Determined

Researchers analysed the molecular structure of amelogenin, a protein involved in tooth enamel formation.
Amelogenin exists in sex-specific variants, allowing scientists to reliably determine whether fossil remains belonged to a male or female individual.

This method bypasses the limitations of skeletal morphology, which often fails in highly fragmentary or sexually dimorphic fossils.

Role of Paleoproteomics

The technique used is known as paleoproteomics, a field developed around three decades ago that focuses on extracting and analysing ancient proteins.

Key features of paleoproteomics include:
• Proteins are more stable than DNA
• They can survive for millions of years under favourable conditions
• They are composed of amino acid chains that preserve biological information

Beyond roughly 100,000 years, extracting usable DNA becomes nearly impossible, making protein-based methods crucial for deep-time evolutionary studies.

Anthropological Significance

This discovery has important implications for anthropology:
• Enables accurate sex determination in early hominins
• Improves understanding of sexual dimorphism in Australopithecus
• Strengthens the use of molecular techniques alongside morphology
• Opens new possibilities for studying social structure and mating patterns in early hominins

It marks a shift from reliance solely on skeletal traits to integrated molecular anthropology.

Why This Matters for UPSC Aspirants

This study is highly relevant for:
• Anthropology Paper-I – Australopithecines, methods in physical anthropology
• Questions on dating techniques, molecular approaches, and fossil interpretation
• Enriching answers with recent scientific advances beyond DNA analysis

Relevant UPSC Anthropology PYQs :

1. Explain the biological changes that made human beings capable of making cultures. 20 Marks | 2018

2. Describe the practical applications of DNA technology in the current scenario. 15 Marks | 2023