The story of human evolution may be far less orderly than traditional textbooks suggest. A fresh analysis of a landmark fossil indicates that our ancient family tree was shaped by a tangled mix of lineages, environmental upheaval and changing populations.
The study focuses on the celebrated Taung Child, one of the most significant fossils ever found. Researchers say the child lived among a much more complicated community of early human relatives than previously recognised.
Discovered in South Africa in 1924, the skull provided the first compelling evidence that human origins lay in Africa rather than Europe or Asia.
For more than 100 years, scientists have treated the fossil as the defining example, or “type specimen”, of the species Australopithecus africanus.
However, an international research team now says the evolutionary setting surrounding the child was considerably more complex.
The analysis places the fossil between 2.96 and 3.03 million years old, a period when southern Africa was undergoing major and repeated environmental changes.
“For over 100 years, we assumed the Taung Child was just one of many similar fossils from the era,” Professor Gabriele Macho of Vrije Universiteit Brussel said.
“Our findings turn that on its head. The human family tree wasn’t a neat, straight trunk – it was a chaotic, tangled bush driven by climate shifts.”
The skull, found in South Africa in 1924, offered the first convincing evidence that humanity originated in Africa
The Taung Child may have lived among a far more diverse group of early human relatives than scientists once believed
Researchers examined the child’s teeth and compared patterns of brain and dental development with those found in other ancient human relatives.
Their results challenge longstanding assumptions about fossils that have repeatedly been assigned to the same species.
The findings do not necessarily mean that the Taung Child was assigned to the wrong species. Instead, they suggest that scientists may have grouped many other fossils with it incorrectly over several decades.
The differences in brain development were especially notable. They point to the possibility that several hominin species lived in the Sterkfontein region at the same time, or occupied it during successive periods.
If the interpretation is correct, southern Africa was not inhabited by a single ancestral human lineage. It was instead home to a varied collection of closely related groups.
The study, published in npj Palaeoecosystems, states: “The discovery of the Taung child marked a turning point in palaeoanthropology and stimulated the search for hominin fossils in Africa.
“Despite numerous Plio-Pleistocene hominin discoveries, particularly in eastern and southern Africa, Taung’s evolutionary position and relationship to other hominins remains unclear.”
The evidence indicates that many fossils may have been incorrectly grouped with the Taung Child for decades
The researchers say repeated shifts between wetter and drier conditions transformed the landscape and frequently separated populations from one another.
As habitats grew and contracted, early human relatives moved, adapted to unfamiliar predators and diseases, and sometimes interbred with neighbouring groups.
Southern Africa’s position between tropical and temperate environments may have made it an important crossroads, allowing populations to split apart and later come back together over thousands of generations.
Fossilised pollen adds another important detail to the picture of the Taung Child’s environment.
The evidence suggests that the region was substantially wetter and more densely forested than the drier parts of South Africa seen today.
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Taken together, the findings challenge a central assumption in human evolution: that fossils from this era can be neatly divided into a small number of ancestral species.
Earlier reconstructions of the Taung Child, pictured, sought to rely on scientific data while limiting artistic interpretation
Instead, the researchers propose that several distinct human relatives may have lived alongside one another in southern Africa around three million years ago, making the origins of our lineage considerably more complicated than previously thought.
“Regarding the potential reasons for early hominin/morphological diversity during the Plio-Pleistocene, we argue that South Africa’s geographic position and the complex population dynamics associated with it may have played an important role,” they wrote.
“Admittedly, disentangling the complex drivers of (species) diversity will be challenging, but it will be essential for determining the origin(s) of our genus Homo.
“The Taung child, the holotype (original physical example) of A. africanus, must stay at the heart of future investigations.”
The most widely accepted estimate is that the child was approximately 3.3 years old when it died. That age is based on detailed studies of tooth development and enamel growth.
Earlier estimates placed the child’s age at between five and seven years, but researchers have since largely revised that figure downward.
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