In an interesting article in the American Scientist associate professor Robert Dorit challenges a common misunderstanding about how evolution works, and explains how the evolutionary process doesn’t necessarily lead to an optimal design.
This perspective [that evolution inexorably leads to optimal adaptations] beguiles in its simplicity, but in the end, it trivializes the complexities of the evolutionary process. Natural selection sorts among existing alternatives, but sometimes a good-enough solution may become inextricably locked in place. Evolution is not about what’s best, but what works.
The placement of alphabet on typewriter/keyboard is a prefect example of how persistence of an early functional solution can account for the survival of a feature – the QWERTY arrangement, in this case. The early solution is often not the best solution, but can have such a tenacious grip that the possibility of other adaptations/changes gets minimized.
There are many explanations for why the inventors of QUERTY keyboard chose this specific arrangement out of total 4 x 1026 ways the alphabet could have been laid out. The most convincing explanation is that this arrangement minimized the mechanical constraint of jamming keys in those old typewriters with metal arcs.
However, the days of mechanical typewriters are gone and we don’t have the jamming-keys issue with our electronic keyboards. Moreover, whether the QWERTY arrangement was the best solution for minimizing jamming is also questionable. But, this arrangement survived the test of time. The QWERTY arrangement, in spite of being a sub-optimal solution, prevailed because it was deeply embedded in the technology and our consciousness.
Can the constraints of history and optimality can play similar role in biological evolution as well? Read the fourth page of this article (here) to understand how the alphabet of our nucleic acid (A, U, C and G) in RNA are not optimally coded. (I have to confess that it took me some time to understand this so called redundancy of the genetic code.)
The power of the evolutionary perspective resides in its acknowledgment of the importance of [the] past. Perhaps more subtly, evolutionary logic makes a profound distinction between history and destiny. We may find great comfort in the idea of inexorable progress, but the products of the evolutionary process, like the products of human ingenuity, are not about perfection.