Ice Age Predators Suffered From Osteochondrosis

According to a new study, saber-toothed cats and dire wolves of the Ice Age often suffered from joint diseases. By examining the bones of predators, scientists found an unexpectedly large number of cases of osteochondrosis.

This is reported by ERR.ee.

Osteochondrosis is a developmental bone disease that is known to affect the joints of vertebrates, including humans and various pets. At the same time, the incidence in wild species is not as well documented, and publications on this topic are quite rare. In a recent study, Hugo Schmeckel and his colleagues from the Evidensia Academy in Sweden found evidence of the disease in the fossil limb bones of saber-toothed cats (smilodon fatalis) and dire wolves (aenocyon dirus). These predators lived during the Ice Age from 55,000 to 12,000 years ago.

The researchers examined more than 1,000 saber-toothed tiger limb bones and more than 500 wolf limb bones from the late Pleistocene La Brea Bituminous Lakes, finding small defects in many bones consistent with specific manifestations of a bone disease called dissecting osteochondrosis. These lesions were mostly observed in the shoulder and knee joints, with a frequency of up to 7% of the bones examined, which is significantly higher than in modern species.

Swedish veterinary surgeon Hugo Schmeckel and his American colleagues took about a thousand limb bones under a magnifying glass. The team found holes with a diameter of less than seven millimetres, characteristic of the disease, in almost six per cent of the bones of young saber-toothed tigers. At the same time, almost three per cent of the limb bones of young primate wolves had holes larger than 1.2 centimetres in diameter. Some adult animals apparently suffered from osteoarthritis throughout their lives. The disease is characterised by the destruction of articular cartilage. The damage was more common in specimens that lived at the end of the Ice Age.

The team suggests that bone disease once reduced the hunting success of large predators. This, in turn, could have affected the number of animals. Instead, the working group, referring to the behaviour of wolf packs, states that by distributing food, they could not starve sick animals. Less is known about the lifestyle of smilodons.

In addition, bone diseases were probably not the main reason for the decline in the number of large carnivores, but rather gave it an impetus. The smaller and more isolated the populations became, the more often inbreeding occurred, when closely related animals mated. This, in turn, reduced the possibility of eradicating harmful gene alleles, including those that contribute to bone disease.

The study is limited to bones from one fossil site, so further study of other samples may reveal patterns in the prevalence of the disease. This, in turn, may shed light on some aspects of the life of these animals.

For example, it remains unclear whether such joint problems could have hindered the hunting abilities of these predators. In addition, degenerative disc disease is commonly seen in modern domestic dogs, which are highly inbred. So, it is possible that the high incidence in fossils could be a sign of declining populations.

The authors add that their study adds to the growing body of literature on the palaeopathology of smilodons and dire wolves, made possible by the unprecedentedly large sample sizes at the Bitumen Lakes and the La Brea Museum. The joint work of palaeontologists and veterinarians confirms that these animals suffered from the same diseases as cats and dogs living in our homes today.