Optimal control is a concept from engineering that has been used with some success in very well-defined industrial problems, but it is not actually common practice even in engineering. The following explores a broader and perhaps more realistic analogy between engineered and biological systems that better reflects the hardware–software distinction introduced above.
[The hardware includes the complete phylogenic set of articulated segments, neuromuscular actuators, sensors, and central neurons available to the species, thereby delimiting its ultimate capabilities, which evolution presumably seeks to optimize. The software includes whatever ontogenic modifications and memories a given individual has managed to accumulate, thereby delimiting its current performance.]
A modern engineer faced with designing, building, and programming a complex system starts first with a set of tasks that it must perform, then figures out the simplest strategies for performing those tasks, then selects the most cost-effective general purpose components that can embody those strategies, and finally assembles the hardware and writes the software as a foregone conclusion. The wise engineer knows that “mission creep” is inevitable, and so he/she designs in as much extra capacity as possible based on currently available “off-the-shelf” technologies, eschewing expensive and risky custom development unless absolutely unavoidable. These stock components themselves represent decades of intensive and expensive development that simultaneously empowers the engineer to achieve a high level of performance at low cost while confining that performance to some arbitrary limits, an acceptable bargain if that performance is “good enough” to meet the original requirements. Inevitably, the product eventually becomes obsolete as newer off-the-shelf technologies emerge (i.e., hardware evolution) and are incorporated into competing products, enabling their programmers to write software that serves new demands that thereby become requirements for competing systems.
A biological organism evolves as an assembly of “off-the-shelf” cellular and molecular components that themselves represent hundreds of millions of years of evolution. These components and the specific organism are optimal only in the sense that their survival indicates that no better designs have yet occurred in the particular ecological niches that they occupy. For most of biological history, performance depended almost entirely on such hardware. The “learning” of primitive organisms is akin to fixed rules for adaptive control that are themselves embodied in the genetic firmware of modulation and messengers, thereby limiting the behavioral repertoire of the organism. At some relatively recent point in evolution, nervous systems became capable of something akin to programming a general purpose computer. It should be noted that the precipitating factor is probably not to be found in the neural hardware itself. The underlying physics of a digital computer are no different from those of a transistor radio, but the emergent properties of those products force us to treat them differently. In particular, the actual performance of the computer depends on both the slow and expensive evolution of its hardware and firmware (now requiring billion dollar silicon foundries) and the rapid and cheap experiments with writing code (suitable for “dotcom” start-up companies). As intelligent biological organisms, humans inherit the best current neural components and system architectures that Mother Nature has yet devised and then spend our countless individual lives hacking together software.
from "Optimal isn't good enough" by loeb