There are a lot of popular clichés about humans among people not as informed as they should be about evolutionary biology that get too much air play and word of mouth. For instance, there’s the claim that we’re the only species that fight each other in groups. Not true. Or that we’re the only species that kills our own kind. Hilariously not true.

Then there’s the metaphor of the human on human predator. This image is usually reserved for those stalking murder or sexual assault victims. Since such individuals rarely eat their victims this predator notion is of course just a metaphor. Yet, looking a little deeper into the metaphor does in fact reveal something profound about us as a species.

Richard Alexander was an early adopter of the now widespread view in evolutionary biology that the main driving force for the evolution of the human brain was the unique competitive conditions of human sociality. Combined with our species’ relative success at insulating ourselves from the other hostile forces of nature, to use Darwin’s phrase, it was in fact other humans who became our primary hostile force of nature. It was other humans who were more likely to act as obstacles to any one of us optimizing our control over resources and mating opportunities.

And the irony of that is that, despite this fact, we’re also a species of unparalleled cooperation. How can both these claims be true? On the most recent episode of The Biological Realist, long-time colleague of Alexander, who has made valuable contributions to these ideas himself, Mark Flinn joins the show to discuss Alexander’s legacy and how these complicated issues play out in the real biological world.

Real human on human predation may be rare, today, but in the metaphorical sense, despite the many benefits of cooperation, we do all remain the primary threat to each other’s evolutionary success. Come over and check it out. Let us know what you think.