Cost of evolutionary adaptation

A second constraints on optimal design pertains to the costs of adaptations. Consider as an analogy the risk of being killed while driving a car. In principle, we could reduce this risk to near zero if we imposed a ten mile-per-hour speed limit and ofrced everyone to drive in armored trucks with ten feet of padding on the inside. But we consider the costs of this solution to be ridiculously high. … The existing fear of snakes that characterizes humans is not optimally designed - after all, thousands of people do get biten by snakes every year, and some die as a result. But it works reasonably well, on average. —p20-21, Evolutionary psychology (book)