How leopard leftovers might help solve forensic cases

When a leopard eats a baboon, what is left behind? This question is not only relevant to primatologists and zoologists. Even though instances of predation on humans is relatively rare, big cats still kill and consume people, and when they do they can virtually obliterate a body. Yet, just like a human criminal, the dining habits of big cats leave tell-tale clues, and in 2004 researchers Travis Pickering and Kristian Carlson fed two captive leopards eight complete baboon carcasses each in order catalog the most useful ways to identify the victim of a big cat kill.

This experimental design is a classic. Way back in 1822, when the English geologist William Buckland was studying Kirkdale Cave in North Yorkshire, he was able to determine that the site was a hyena den by comparing the gnawed bones from the cave to the bones given to living hyenas at a zoo. In the case of Pickering and Carlson, though, the scientists were after more delicate details. Specifically, they wanted to know which bones regularly turned up as refuse (bits and pieces which were strewn about during feeding) and which commonly came out in vomit or scat. If certain bones are more likely to turn up as refuse or scat, then forensic investigators can direct their attention to certain aspects of a cat kill to glean the most information about the victim's identity.

As expected, the researchers saw a pattern emerge when what was left of the baboons was recovered from the cats. Parts of the upper spine, shoulderblades, hips, and limb bones were most frequently found in the refuse assemblages, while parts of the mid- to lower-spine, hands, and feet were found in the scat. This latter finding was particularly significant. The leopards typically proceeded to eat the hands and feet of the baboons by eating one joint at a time. This means that the relatively small finger and toe bones wound up in the scat nearly intact, oftentimes with some soft tissues attached, and so when a human is killed by a big cat it would be wise for investigators to pick through any scat they find in the hope of finding part of a finger or toe with enough flesh still on it to provide a fingerprint.

As the authors suggest, it seems that scat has greater potential to help investigators identify the victim of a big cat than the scattered remains in the refuse collections. The only exception to this may be teeth, which would be found in the collection of non-digested bones since leopards did not consume the skulls of the baboons (and hence would probably be unlikely to attempt eating human heads). Equipped with this background information, forensic scientists will hopefully be better able to analyze big cat kills.

Yet the benefits of such studies extend beyond forensic science. Leopards and other big cats have been hunting primates, including hominins, for millions of years, and the patterns identified by Pickering and Carlson will help paleontologists identify bones accumulated by carnivores in the fossil record. In fact, many famous fossil human specimens, from the Homo erectus of Dragon Bone Hill in China to Orrorin from Kenya, show signs that they were collected by the activities of carnivores. Odd as it may seem, the dining habits of carnivores may have allowed for the preservation of numerous fossil humans.

For more on carnivore-primate interactions, see my posts on tamarin-hunting margays and why leopards prefer big monkey which travel in groups.

PICKERING, T., & CARLSON, K. (2004). Baboon taphonomy and its relevance to the investigation of large felid involvement in human forensic cases Forensic Science International, 144 (1), 37-44 DOI: 10.1016/j.forsciint.2004.03.003