Journal on Policy and Complex Systems
zations . From The Edge of Organization ( Marion , 1999 ):
In a coevolving system of potential energy landscapes , actors perturb each other ' s landscapes and knock each other out of their holes . Imagine marbles on a vibrating potential surface . Typically they will pop in and out of holes , but as they work their way into ever deeper holes it gets increasingly difficult to pop them out . Eventually marbles find a hole so deep that the vibrations no longer dislodge them . Similarly , actors on coevolving landscapes are not allowed to rest on their laurels . They perturb one another ; new actors enter the stage and existing ones leave it ; and in the process , actors work themselves into deeper and deeper holes .... ( p . 248 )
I can see several misunderstandings about coevolution in that quote , some of which could have been caused by flipping the landscape . ( Marion does include Templeton ’ s shaking force , though it is much weakened .)
1 . Coevolving species do not only “ knock each other out ” of optimality : sometimes they boost each other into it . This is harder to imagine when a boost towards greater fitness looks like a nudge over a cliff .
2 . A population that reaches a state of locally maximized fitness is not just as likely to “ pop out ” out of that state again , because “ locally maximized fitness ” means higher fitness surrounded by lower fitness . That is , life surrounded by death . Such a state is easier to imagine when you view optima as peaks . ( Yea , though I walk through the valley of the shadow of death , I will fear no evil .)
3 . No population is ever so perfectly adapted that changes in its environment “ no longer dislodge ” it . Just ask the dinosaurs . That is why the vision of a mountain peak , with its multiplicity of paths and crumbling erosion , is such a useful representation of the uncertainty inherent in evolution . Mountains and holes erode , but when we think of erosion we think of mountains .
4 . Coevolution does not cause actors to “ work themselves into ” increasingly optimal states . The best that can be said is that things change because of coevolution . Whether the change is adaptive or maladaptive depends on context and history . The image of marbles falling into deeper and deeper holes makes such an increase seem certain , but it is not .
Flipping the adaptive landscape opens the door to a different set of explanations about evolution , one that tends toward increased certainty and teleology . Evolution , however , is anything but certain . In the story of any population , some organisms live to reproduce and some die first , and the ones that lived were more likely to live , and we can see that because they ... lived . It is obvious only in retrospect , like Paine ’ s keystone species , and like Lorenz ’ s butterfly .
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