- Fossils of the nearly complete 3.8-million-year-old skull of Australopithecus anamensis. [Credit: KNM-WT/T. Riba, Nariokotome, Kenya]
The discovery of a nearly complete 3.8-million-year-old skull of Australopithecus anamensis in Kenya in 2016 is providing new insights into the evolution of our human ancestors. The skull, which is the oldest known ancestor of the genus Homo, to which modern humans belong, is helping to fill in some of the gaps in our understanding of how we evolved from ape-like ancestors.
Key findings:
1. Evidence of a mosaic of traits: The skull of Australopithecus anamensis shows a mix of primitive and more modern features, suggesting that it may have been a transitional species between earlier ape-like ancestors and later human-like ancestors.
2. Smaller brain, bigger face: Compared to earlier hominins (ancestors of humans), Australopithecus anamensis had a smaller brain but a larger face, particularly in the region of the jaws and teeth. This suggests a shift in diet towards a more plant-based diet, requiring stronger jaws and teeth.
3. Bipedal but tree-dwelling: The shape and structure of the skull indicate that Australopithecus anamensis was fully bipedal, walking upright on two legs, but its long arms and curved fingers suggest it spent a significant amount of time climbing trees.
4. Diverse group of ancestors: The discovery of Australopithecus anamensis alongside other hominin species from around the same time period suggests that there may have been a diverse group of early human ancestors, rather than a single linear progression from one species to another.
5. Reevaluating the timeline of human evolution: The presence of Australopithecus anamensis in eastern Africa 3.8 million years ago challenges previous estimates that the human lineage diverged from chimpanzees around 7 million years ago. It suggests that this divergence may have occurred earlier.
The skull of Australopithecus anamensis is providing valuable information that is helping to refine our understanding of the complex evolutionary history of our human ancestry. It allows scientists to gain insights into the physical characteristics, behavior, and ecology of our early ancestors and helps us to piece together the intricate tapestry of human evolution.
