The discovery of the Taung child’s skull in 1924 was a seismic moment in understanding human origins. It was the first Australopithecus specimen ever found. As such, it’s the holotype of the group—the standard measuring stick future specimens were judged by. Now those specimens are coming under renewed scrutiny in a study published in npj Palaeoecosystems.
An international team of paleobiologists decided to give the Taung child’s noggin a fresh look, and the more they looked, the more discrepancies they found. By comparing the rate of tooth mineralization with chimpanzees, gorillas, humans, and other fossils, the team determined the skull likely belonged to a child (not a juvenile as the original investigating anthropologist surmised). Analysis of the dentine-enamel junction (where the tooth’s hard shell meets its chewy center), revealed a resemblance to Paranthropus robustus, a more ape-like hominin that likely originated after Australopithecus.
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Focusing on the braincase, the researchers found other discrepancies. Using chimp and gorilla skull growth as a guide, they compared digitally reconstructed skulls found in the same region and purported to belong to Australopithecus to the Taung child’s braincase. They found that the size and shape of the Taung child’s skull indicate it could have grown into a hominin resembling some of the Australopithecus specimens, but not others.
In other words, the team’s modeling indicates there was a lot more variation among hominins living in the area at the time, and lumping them all into Australopithecus may downplay this diversity. Their investigation of the paleoclimate at the time paints a picture of a region in flux, and they hypothesize these shifts were fueling hominin diversity. As wet and dry cycles continually remodeled the region, hominin populations expanded and contracted, confronting new pathogens and predators, diverging, and interbreeding, according to their theory.
“For over 100 years, we assumed the Taung Child was just one of many similar fossils from the era,” study author Gabriele Macho of Vrije Universiteit Brussel said in a statement. “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.”
Of course, it’s important to note it’s merely a hypothesis. Still, if the past 20 years have taught us anything, it’s that our family tree has more branches than we previously thought.
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Lead Image: Didier Descouens / Wikimedia Commons
