exact a greater cost than the benefit of acquiring the resource. You would expect clever birds to realize that they might have to fight someday, so they better scout their potential opponents by observing them in battle. The observers (or “eavesdroppers” in biolingo) could choose to be either a hawk or a dove when it’s their turn to fight—depending on what they’ve observed about their adversary.

Rufus Johnstone, of the University of Cambridge, extended the math of the hawk-dove game in just this manner to evaluate the eavesdropper factor. In this game, the eavesdropper knows whether its opponent has won or lost its previous fight. An eavesdropper encountering a loser will act hawkish, but if encountering a winner the eavesdropper will adopt a dove strategy and forgo the chance to win the resource.

“An individual that is victorious in one round is more likely to win in the next, because its opponent is less likely to mount an escalated challenge,” Johnstone concluded.11

Since eavesdroppers have the advantage of knowing when to run, avoiding fights with dangerous foes, you might guess that eavesdropping would reduce the amount of violent conflict in a society. Alas, the math shows otherwise. Adding eavesdroppers to the hawk-dove game raises the rate of “escalated” fighting— occasions where both combatants take the hawk approach.

Why? Because of the presence of spectators! If nobody is watching, it is not so bad to be a dove. But in the jungle, reputation is everything. With spectators around, acting like a dove guarantees that you’ll face an aggressive opponent in your next fight. Whereas if everybody sees that you’re a ferocious hawk, your next opponent may head for the hills at the sight of you.

So the presence of spectators encourages violence, and watching violence today offers an advantage for the spectators who may be fighters tomorrow. In other words, the benefit to an individual of eavesdropping—helping that individual avoid high-risk conflict—drives a tendency toward a higher level of high-risk conflict in the society as a whole.

But don’t forget that adding spectators is just one of many

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