Human cooperation often gives way to a desire for self-expansion, or to fear-driven tendencies to protect against such predatory tendencies in others. In fact, “a great proportion of all efforts in the world are employed in merely neutralizing one another…energies…spent by mankind in injuring one another, or in protecting against injury (John Stuart Mill).” Mill’s observation has its game-experimental analogue in predator-prey contests that are used here to unravel the neurobiological underpinnings of greedy predation and fear-driven defense. I will present “work in progress” (with Frans van Winden, Michael Giffin, Mariska Kret, Richard Ridderinkhof, and Ilja Sligte, among others) examining two key brain circuitries–the amydgala (involved in threat-detection) and the prefrontal cortex (involved in self-control), along with three neurohormonal modulators–oxytocin, cortisol, and testosterone. Results converge on the possibility that (i) greedy predation is relatively calculative, conditioned by the prefrontal cortex, and reduced by empathy-inducing oxytocin, whereas (ii) fear-driven defense is more intuitive, conditioned by the amygdala, and modulated by stress-regulating cortisol. A study using neuro-navigated Theta-Burst Stimulation suggests that activated (versus disrupted) prefrontal cortex reduces predation but also increased prey-defense. Accordingly, cooperation can be rescued, and wasteful conflict reduced, by increasing (prefrontal cortex modulated) self-control and risk-aversion among those desiring to increase relative wealth while, simultaneously, relaxing control and risk-aversion among those fearing possible predation.