Ancient humans and hyenas in a battle of the scavengers

Our ancient human ancestors may have been able to hold their own against large scavengers, such as giant hyenas, according to modelling by European researchers.

In the late Early Pleistocene (roughly 1.2 to 0.8 million years ago) hominins – the group that includes humans and our extinct relatives – would have had to compete with other scavengers over carcasses abandoned by sabre-toothed cats and jaguars.

The study which models population dynamics is published in Scientific Reports. It suggests that moderately-sized groups of hominins may have been the most successful scavengers.

A computer simulation was run to test the competition for carrion between hominins and giant hyenas (Pachycrocuta brevirostris) in the Iberian Peninsula a million years ago.

They also used their model to see whether large apex predators like sabre-toothed cats (Homotherium latidens and Megantereon whitei) and extinct European jaguars (Panthera gombaszoegensis – double the size of modern jaguar) would have left enough flesh to support hyena and hominin populations.

It seems it depends on the size of the group of hominins vying for a ready meal.

Scavenged meats would have been a valuable source of protein and fat for these hominins, especially in winter when plant resources were scarce.

The authors found that teams of 5 or more individuals would be capable of chasing away giant hyenas. They also found that hominin populations exceeded that of giant hyenas by the end of the simulation.

If the hominins scavenged in very small groups, however, their population lasted to the end of the simulation only when there was a high predator density, meaning there would be more opportunities to scavenge.

The simulation gave a potential optimum group size of scavenging hominins as between 10 and 13.

More than 10 and the ancient humans were able to chase away even sabretooths and jaguars. But more than 13 and the hominins required more carcasses to sustain their numbers and energy expenditure.

“The results showed that maintaining an optimum group size can be an important factor for success in the competition for carrion in the form of interference competition,” the authors write. “Therefore, an optimum group size protects against predation and improves scavenging efficiency.”

But the authors note that these numbers were based on arbitrarily assigned values for the hominin group size required to scare away hyenas from a carcass.

While based on assumptions, the research gives a glimpse into what it took for our early human relatives to survive in the early Late Pleistocene. It required a bit of teamwork to discourage other scavengers from carrion so that ancient hominins could get their fill from these sources.