Algorithmic efficiency in the face of inelegance

March 1st, 2008 | by ian |

Seed magazine published a wonderful crossover article between the worlds of biology and engineering “Algorithmic Inelegance

The complexity of developmental regulation isn’t a product of design at all, and it’s the antithesis of what human designers would consider good planning or an elegant algorithm. It is, however, exactly what you’d expect as the result of cobbling together fortuitous accidents, stringing together helpful scraps into an outcome that may not be pretty, but it works. That’s all evolution needs from developmental processes: something that works well enough, no matter how awkward or needlessly complex it may seem.

Biological solutions can be remarkably efficient (well adapted thanks to evolution by natural selection) while being absurdly backwards in design. Nerves in the mammalian eye pass on top of the rods and cones that collect light yet I can’t complain about my eyesight (other than the need for contacts but that’s another story). Cephalopods apparently have more accurate vision thanks to happier circumstances:

The vertebrate retina is wired “backwards”. That is the photoreceptors point to back of the retina, away from incoming light, and the nerves and blood vessels are on the side of the incoming light, this means that any image formed on the vertebrate retina has to pass though layers of blood vessels and ganglion cells, absorbing and distorting the image….Now consider the eye of squids, cuttlefish and octopi. Their retinas are “rightway round”, that is the photoreceptors face the light, and the wiring and the blood vessels facing the back (1). Squid and octopi have no blind spot; they can also have high visual acuity. The octopus also has a fovea-equivalent structure, which it makes by packing more (or longer) photoreceptors into a given area (1). Because it doesn’t have to create a hole in the supporting tissue it can have arbitrarily large “fovea”, and greater visual acuity. Cuttlefish have better visual acuity than cats (2) and because of their “rightway round” retinas; this level of acuity covers nearly the entire retina (1,2) unlike vertebrates where it is confined to the small spot of the fovea.

More on this fascinating story here.

The author seems to indicate that human engineers would shy away from the needless complexity that evolution by historical accident seems to create. However, today’s leading engineers faced with shifting requirements, overwhelming problem complexity, or incomplete understanding of the science behind the solution may well adopt an evolutionary strategy toward solving a problem, as many circuit and drug designers have already done successfully. (I’ll try and dig up some references). They start with a modular design with lots of simple parts that can be tweaked and rearranged quickly, set up replication with random modification and a process for selecting the best fitted solutions. Like artificial selection, or breeding, you can achieve results quickly. This is similar to what successful organisms do, molded by the evolutionary process of natural selection working hand in hand with mutation and reproduction. And it explains why we burn brightly on this earth, have sex, and above all why we are programmed to die.

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