Saber-toothed Cats Show High Spinal Tumor Rates, Indicating Inbreeding

Fossilized vertebrae from the La Brea Tar Pits have revealed an unusually high incidence of spinal nerve tumors in saber‑toothed cats (Smilodon fatalis). Researchers from the University of California, Los Angeles, noted that the tumors—rare in modern felids—were present in more than 20 % of the examined specimens, far exceeding the prevalence seen in contemporary big cats. The lesions likely caused chronic pain and impaired limb function, which could have compromised the animals’ hunting efficiency.

The study, published in the journal *Paleobiology*, interprets the tumor pattern as a sign of inbreeding that intensified in the final decades of the species’ existence. Genetic bottlenecks, combined with environmental pressures, may have reduced genetic diversity and increased susceptibility to neoplastic disease. The researchers suggest that debilitated individuals would have been more easily trapped by prey animals that fell into the tar, accelerating the decline of the population.

These findings add a new dimension to the understanding of Smilodon extinction, indicating that internal health challenges, not only external factors, contributed to the species’ demise. Further comparative analysis of other megafaunal fossils from the same site may clarify whether similar disease patterns were widespread among late‑Pleistocene fauna.