27 Primate Species. Zero Abfraction Lesions. Just You.

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TL;DR: Scientists examined 500+ teeth from 27 wild primate species — gorillas, orangutans, fossil apes — and found zero instances of the gumline damage your dentist diagnoses every day. That one is apparently just us.

The Situation

Jaw clenching, teeth grinding, expensive night guards, and the slow accumulation of dental bills that no one budgeted for — the discourse around stress-induced dental destruction has been building steadily across TikTok and Reddit for months. The comments on any video about veneers or dental tourism are full of people comparing their abfraction lesions, their cracked molars, and their dentist's tone of barely contained judgment. "Why is everyone's jaw destroyed?" is the question that keeps circulating, and the working consensus has been some combination of stress, coffee, and the particular psychic toll of reading news in real time.

Researchers Ian Towle and Luca Fiorenza were not investigating that discourse. They were investigating toothpick grooves in fossil human teeth — specifically whether the narrow channels on ancient molars, long attributed to deliberate dental hygiene with sticks and fibres, might have a less culturally interesting explanation. To answer this, they needed a comparison group. So they examined more than 500 teeth from 27 primate species — gorillas, orangutans, macaques, colobus monkeys, fossil apes — all sourced from wild populations, meaning none of the specimens had ever encountered a toothbrush, a sports drink, or a 10pm anxiety spiral.

Published in the American Journal of Biological Anthropology, the study confirmed that groove-type lesions do appear naturally in other primates without any evidence of tool use, undermining decades of assumptions about ancient human behaviour. But the more striking finding was an absence. Across all 500+ teeth and all 27 species — including animals with dramatically powerful bite forces and diets that include bark, hard seeds, and tough vegetation — the researchers found not a single abfraction lesion. The deep, V-shaped gumline notches that dentists diagnose daily, so common they have a standard treatment protocol, do not appear anywhere in the wild primate dentition studied. The researchers concluded they are, in all available evidence, uniquely human.

By the Numbers

The Deeper Question Nobody Asked

Gorillas eat tough roots and hard bark with the kind of bite force that would shatter a modern dental crown at breakfast, and their teeth show natural wear but no abfraction damage. Humans eat processed food, use electric toothbrushes with adjustable pressure settings, and receive professional guidance on technique twice a year — and yet the wedge-shaped gumline lesion is a staple of any general practice waiting room. The researchers place abfraction alongside impacted wisdom teeth and misaligned dentition in a growing subfield called evolutionary dentistry, the study of dental problems that are rare in wild primates but routine in humans, which raises an obvious follow-up question: if this damage can be traced specifically to electric toothbrushes, carbonated drinks, and grinding, and not to anything in the 50-million-year primate dental record, exactly which part of modern civilisation is the field recommending we reconsider first?

Sources

• Scientists may have debunked one of humanity's oldest habits — ScienceDaily / The Conversation, June 8 2026 — overview of the study with analysis by authors Ian Towle and Luca Fiorenza
• Non‐Carious Cervical Lesions in Wild Primates: Implications for Understanding Toothpick Grooves and Abfraction Lesions — Towle et al., American Journal of Biological Anthropology 188(2), 2025 — original peer-reviewed paper