Ancient Tooth Pitting May Reveal Hidden Clues to Human Evolution!
What were once thought to be signs of dental disease or malnutrition on fossilised teeth might actually be something far more significant: a genetic breadcrumb trail leading back through our evolutionary past.
A recent study published in the Journal of Human Evolution has shed light on an unusual feature found on fossilised molars from the extinct hominin genus Paranthropus. These tiny, shallow, circular pits, dubbed “UCS pitting”, appear to be more of a consistent biological trait than a flaw, and could help scientists better trace our evolutionary lineage.
Photo Credit: Towle et al., Journal of Human Evolution (2025)
The research, led by Ian Towle from Monash University’s Palaeodiet Research Lab, examined teeth from sites across eastern and southern Africa, covering over two million years of hominin history. According to Towle, teeth are remarkably informative when it comes to understanding our past. “This specific type of pitting might turn out to be a unique marker for certain evolutionary lineages,” he told Live Science. “It could help us better identify fossil species.”
Unlike other signs of enamel stress, like horizontal grooves or widespread damage, the UCS pits are evenly spaced and remarkably uniform in size. They’re found primarily on the thick enamel of molars and show no signs of being caused by environmental stressors like poor diet or illness. This strongly suggests the pattern is genetic in origin, rather than the result of external pressures.
Most examples of UCS pitting have been found in species like Paranthropus robustus from South Africa, and other Paranthropus species from East Africa. Interestingly, a few examples have also turned up in much older fossils from Australopithecus in Ethiopia’s Omo Valley, dating back nearly three million years. However, more than 500 Australopithecus africanus teeth from southern Africa showed no such pitting, suggesting a possible evolutionary split between these regional populations.
Photo Credit: Towle et al., Journal of Human Evolution (2025)
What’s particularly fascinating is that traces of UCS-like pitting have also been spotted in a few rare fossils from other hominin species, such as Homo floresiensis (the “hobbit” species from Indonesia) and Homo luzonensis from the Philippines. Although their presence in these species is intriguing, Towle cautions that they are too rare to draw firm conclusions. “More research is needed before we can confidently use UCS pitting as a taxonomic marker,” he explained.
Further strengthening the idea that this pitting isn’t the result of disease is the comparison to a rare modern condition called amelogenesis imperfecta. This disorder, which affects about one in a thousand people today, also disrupts enamel formation in a similar way. However, UCS pitting appears in up to half of Paranthropus specimens, and has remained consistent across millions of years. That strongly suggests it wasn’t a harmful condition but rather a characteristic feature of the genus.
This discovery could add a valuable new tool to the palaeoanthropologist’s toolkit. Just as enamel thickness and tooth cusp patterns help distinguish ancient species, UCS pitting could become another reliable trait for mapping out the branches of the human family tree.
Looking ahead, scientists hope to use cutting-edge techniques like palaeoproteomics, the study of ancient proteins preserved in enamel, to dig deeper. This could help determine whether the pitting relates to sex-specific traits or other genetic features unique to Paranthropus.