Competition in the Plio-Pleistocene East African large carnivore guild: impact of hominins
The large carnivore guild in East Africa today is a. remnant of its past diversity, with 6 species of body mass greater than 21 kg: 3 species of Felidae, 2 species of Hyaenidae (of which one is mainly a scavenger/frugivore), and 1 species of Canidae. In contrast, at its peak some 3 million years ago, that guild comprised at least 14 species larger than 21 kg body mass, including 6 species of Felidae, 4 species of Hyaenidae, as well as Canidae, Mustelidae, and Ursidae. The gradually increasing encroachment of the human lineage on the ecospace of the large carnivore guild would likely have had consequences for the carnivores. I have previously argued that the loss of species among large carnivores was a result of increasing hominin cognitive ability. If this is the case, we must ask what specific factors could have led to this decrease. One such aspect is competition between large carnivores for prey. Preliminary data from δ13C values in carnivore tooth enamel from a range of sites in the Omo-Turkana Basin, Kenya indicates that, contrary to expectation, all carnivores had a similar grazer/mixed feeder dietary mix around 4-2 Ma. Coupled with the greater species richness, this indicates substantially greater competition in the large carnivore guild than at present, leading to a situation where the addition of another competitor may have destabilized the guild with species loss as a consequence.