An Evolutionarily Stable Strategy (ESS) is a strategy that cannot be beaten if adopted by a population. It’s a subset of game theory arrived at through natural selection, where species compete for resources and make ‘rational’ decisions about their relative payoffs. Memes evolve through natural selection like genes, and for both, the best evolutionary strategy for the individual depends on what the rest of the population are doing. When major environmental changes occur, the ‘Meme pool’ (an analogy to the ‘Gene pool’) falls into a state of instability, oscillating between strategies until equilibrium is achieved. Using game theory you can demonstrate in relatively simple terms how seemingly counter-intuitive traits like cooperation could evolve as a dominant strategy among self-interested individuals.
Cooperation risks incurring some cost to yourself for the benefit of the group. On surface level this shouldn’t occur, other than to help closely related family members, because evolution compels us to pass on our genes above all others. As British biologist JBS Haldane quipped “I would lay down my life for two brothers or eight cousins”, referring to the fact that our siblings on average share 50% of our genes and cousins 12.5%. However in war humans lay down their lives for complete strangers, on the basis of a shared religion or imaginary national borders. Much of our how modern economy works necessitates peaceful cooperation between people we’ve never met, and may never see again. Most of us enjoy the ability to walk out of our house unarmed, take a public bus to the city centre, and buy a croissant and a coffee – without interacting with a single blood relative – and with zero risk of being savagely attacked. Why is that?
Some talk about group selection, the theory that sometimes evolution acts on whole groups of organisms, but actually this premise isn’t necessary to explain how altruism can arise. Consider two tribes, the ‘Hawks’ and the ‘Doves’. Members of the Hawk clan were taught by their Elders to always fight tooth and nail if threatened, and Doves were taught to ‘turn the other cheek’. Neither strategy is stable: the Hawks will tear themselves apart infighting, and the Doves never stand their ground to protect resources. Hawks initially dominate through aggression, and when there are mostly Hawks, Doves survive by hiding and letting them fight it out. However if the Hawks destroy themselves in a civil war and the Doves come out of hiding, all it takes is a single defector back to the Hawk way of life to decimate the weakly held peace.
Then a wise old master, tired of all the fighting, teaches a new concept – ‘Retaliation’ – "An eye for an eye and a tooth for a tooth.". Only fight if attacked, otherwise protect the peace. As Dawkins describes: “A retaliator behaves like a hawk when he is attacked by a hawk, and like a dove when he meets a dove. When he meets another retaliator he plays like a dove. A retaliator is a conditional strategist. His behaviour depends on the behaviour of his opponent.” This idea spreads like wildfire, because it’s always better for the individual than the Hawk or Dove strategies. When it reaches critical mass, it dominates. Most people, most of the time, interact peacefully as Doves. Though if someone breaks the peace, we activate Hawk mode and take them down. This acts as a deterrence to anyone thinking of defecting, and over time removes anyone with Hawkish tendencies from the ‘meme pool’. As this thought experiment shows, Memes have no objective value, separate from the surrounding culture: Hawkishness dominates only until Retaliation appears. We’re never dealing with evolution in isolation: it’s survival of the ‘fittest’, as in the best fit to the current environment.
The reason ‘Retaliation’ is an Evolutionarily Stable Strategy is that we never go back to full Dove or Hawk: the system is self-correcting. When people get too soft and Dovish, Hawks start to reappear to take advantage. When Hawks get out of control, otherwise peaceful members of the population stand up and fight. Those willing and able to fight get institutionalised as a protected class – warrior, police, lawyer – who are given conditional permission by society to punish defectors. We also never fall back into a fully Hawkish society: Doves that lose power hide in waiting, until Hawks turn on each other and there’s an opportunity to retaliate. Once an evolutionarily stable strategy is reached, the balance of power only gets disrupted by large technological or environmental shifts. If a new valuable resource is discovered society goes temporarily Hawkish in order to capitalise on it. If a new technology makes our lives easier, we might get too complacently Dovish for a time. Cultures who navigate this successfully outgrow those that don’t, and eventually assimilate or eradicate less well balanced groups.
A Simple Game: Hawks and Doves
Eye for an eye, Wikipedia
Game Theory, Evolutionary Stable Strategies and the Evolution of Biological Interactions
Greed Is Good (Unless You’re Human)
Kin selection, group selection and altruism: a controversy without end?
Origins of altruism: why Hamilton still rules 50 years on
Richard Dawkins Quote, Retaliator