Local Optima: Survival of the Imperfect
What do a peacock, a toilet tank, and a diamond have in common?
They all are examples of an animal, a device, or a chemical compound that is stable but not necessarily in its most efficient or effective form. In biology this is called the local fitness peak, in technology we call it the local optimum, and in chemistry it is a local energy minimum.
The detailed mechanism of how these outcomes are arrived at differ wildly, but there are similarities that might provide some insight into the world we live in.
This concept permeates nearly everything around us. Many things, in one way or another, are an example of a local optimum. An optimum based on the specific constraints or conditions in place for that situation. To move to a better or more stable optimum requires overcoming a barrier. The barrier can be energy, ideas, resources, or simply surviving a transitional period. Because this is difficult, things often remain stuck where they are.
Biology
The plant and animal world is littered with examples of designs which are clearly not optimized in a general sense, but in their local environment, are the best solution. Birds are a great example. The diversity of unusual and extreme bird designs that exist are often fine tuned to their immediate environment. This includes specialized beaks, plumage to attract mates, extraordinarily long necks, or any number of bizarre features.
Take the peacock. The incredible feathers on the male peacock serve an important purpose: attract a female peacock. Yet these feathers have a downside. They are actually a hindrance to almost anything else it does. However, in the biological niche it inhabits, it is currently at a fitness optimum. The plumage helps attract a mate and any less will hurt that effort, but too much of it creates other problems, like making movement and survival more difficult. So the peacock right now is at a perfect balance.
At one time dinosaurs ruled the Earth, but when the Chicxulub meteorite struck, it disrupted the existing biological balance. This opened opportunities for other animals, and after things settled down, millennia later, a new local fitness optimum emerged, leading to the age of the mammals.
Humans are not immune to this phenomenon. Even our brain size is a compromise. First it has to fit through a pelvis during birth, then requires many years of childhood to enable further development. If designed from scratch we might allow for larger brains by having the baby emerge without having to go through a narrow passageway.
Technology
In technology the toilet tank is an example. It is a complicated contraption, prone to failure, with lots of components. However, it stays largely as the standard for a variety of reasons. Technological systems have constraints that, in one way or another, usually come down to cost. There is a large installed base of manufacture. It would be costly to change, even if we had a superior design. In these man-made situations there are other issues as well. A better solution may exist, but perhaps it hasn’t been discovered yet.
Arriving at better local optima may be the main thing driving the advancement of technology. And we end up with wonderful new devices which are better than what existed previously but still not ideal. Along the way we pause at these local optima which have plenty of room for improvement.
Chemistry
Starting to stretch the idea a little, in chemistry substances naturally tend to find their lowest energy state, the energy minimum. A diamond is a form of carbon that exists in a local energy minimum, but graphite sits at a lower energy level and is more stable. To move from a diamond to graphite requires an input of energy to overcome an energy barrier. Similar forces are at play for molecules, resulting in many chemical compounds which are stable but not the most stable form. And we are lucky that happens, because the ultimate stable form for the elemental components of a human body would be a bunch of carbon dioxide, water, nitrogen and a few pounds of inorganic oxides.
When constraints are removed
When released from the confines of real constraints, for example in the minds of Hollywood writers, we get some amazing creatures. Like the villain in the alien movies: mouth within a mouth with crazily effective teeth, ability to implant parasitic eggs within the torso of a human, a nearly impervious exoskeleton, extraordinary athletic ability and speed… And this could indeed represent an optimum that just never had the chance to develop. Or it could be that there are unanticipated problems that would arise preventing such a creature from being successful.
So rather than lamenting that imperfect things exist, the suboptimal equilibrium is something to be celebrated. Without it life as we know it would be impossible.
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