Scientists from the University of Vienna have determined the biological sex of four Paranthropus robustus individuals from South Africa, dating back about two million years. This work also represents the oldest genetic data recovered from a human relative. A preprint discussing the findings has circulated within the scientific community.
Hominins form a subfamily within Hominidae, which also includes Homo sapiens, chimpanzees (Pan), gorillas (Gorilla), and several extinct lineages.
In the study, researchers conducted mass spectrometric analysis of tooth enamel proteomes from the four Paranthropus robustus specimens, which lived in southern Africa roughly 2.8 to 1 million years ago. For years, scholars debated whether Paranthropus robustus was closer to Australopithecus or a distinct lineage, with interspecies relationships remaining uncertain. While DNA data can settle such questions, suitable ancient samples for sequencing had not been available until now. Enamel, a durable tissue, can preserve proteins across vast spans of time, enabling a proteomic window into deep ancestry.
The team extracted and compared enamel proteins across the samples, successfully identifying consistent amino acid profiles with minimal contaminant signatures. Based on the proteomic data, two individuals were determined to be male and two to be female, providing rare insight into sex distribution within these early hominins. The analyses also suggested that these Paranthropus specimens were more closely related to Homo than to other primates. Specifically, researchers cataloged 17 hominid-facing single-nucleotide polymorphisms, with only two sites, COL17A1-636 and ENAM-137, showing an allelic state different from the modern human reference. These results place Paranthropus robustus nearer to the Homo lineage than to other branches in the primate family tree, while leaving room for future refinement as more data become available.
Overall, the findings illuminate how ancient enamel proteins can be used to investigate deep evolutionary questions, including lineage relationships, sex dimorphism, and patterns of genetic variation in early hominins. This approach broadens the toolkit for paleogenomics, offering a complementary path when DNA is not preserved, and it helps frame how Paranthropus robustus fits within the broader narrative of human evolution. Ongoing work aims to expand sampling, verify results across additional specimens, and integrate protein data with morphological and archaeological context to build a richer portrait of early hominin diversity.