A rumination on gears
As promised we now return to the topic of animal gears. I begin by admitting that my memory fails me for although I can tell you that the research which first announced this discovery appeared in September, I cannot recall where I learned of it. My best guess is that I came across some micrographs while searching for images to illustrate a recent, and not unrelated, post which concerned the leaping ability of the flea. The internet being what it is I now know that this story has achieved nearly viral status; it was the subject of a report on NPR, and was even the topic of a post at another WordPress blog. The story is a one which involves the nymphs of a little Planthopper by the name of Issus. In much the same way as the flea, Issus leaps great distances as it moves from place-to-place. To jump in as straight a path as possible it is important that Issus’ rear legs be in perfect synchrony. You can imagine how asymmetries in jump trajectory could be generated if one leg or the other lead, lagged, or otherwise jumped-the-gun during launch. As a mechanism to ensure that the legs act together, a tiny set of gears may be found along the trochanter which is, in human terms, much like a knee joint between the coxa and femur of the leg. The action of the gearing is to synchronize the legs by providing a mechanism which links their movements.
Interesting, to be sure, but what strikes me most about reports of this discovery is the tone of surprise adopted by nearly all who describe it. Is it because people believe so strongly that only humans are capable of feats of engineering and good design? Do we not understand that a great number of human architectural constructions are simply mimics of nature’s own? A long-ago post about mimetics which appeared here focused on the many parallels between natural and artificial forms, and recognized that these parallels fostered the development of the field of Biomimicry which looks to nature for answers to solutions to human problems. So, given that solutions to many of our engineering challenges had already been solved, perhaps millions of years ago, why are we surprised when we discover something like Issus’ geared legs? Perhaps because the first principles of good gearing were developed and practiced by humans, including Leonhard Eular, back in the eighteenth century such that people think that we got it first? Guess what? We didn’t.