An alien landing on Earth would, Hermann J. Muller deduces from biological principles, find our species as just another weird type in the possible infinite diversity of weird types:
The alien would find it most remarkable that we had an organ combining the requirements of breathing, ingesting, tasting, chewing, biting, and on occasion fighting, helping to thread needles, yelling, whistling, lecturing, and grimacing. He might well have separate organs for all these purposes, located in diverse parts of his body, and would consider as awkward and primitive our imperfect separation of these functions. Thus, for the science fictionist to picture the alien with an absurdly all-purpose mouth like ours, as he usually does, is a prime example of the prevalence among our supposed intelligentsia of utter unsophistication in regard to basic biological matters.
Our example of the mouth is by no means the most striking of its kind that might be given. The whole concept of the head as we think of it is pretty much a man-centered or rather, a vertebrate-centered one, as one realizes when examining a spider, octopus, or crab, in which the head and much of the trunk are merged. Moreover, neither the organs of hearing nor of smell need be near the brain or mouth - as witness the grasshopper, which has its ears in its abdomen, and the fly, which smells and tastes with the tips of its feet. Again, consider the scallop, a headless but alert mollusc that can swim actively and whose many eyes, structured much like ours, are arranged in a long row on the mantle, just beyond the edge of each shell. So we could go on and on, citing the seeming outré of this very planet earth as evidence of our own singularity.
(Quoted from “Life Forms to Be Expected Elsewhere Than on Earth,” by H. J. Muller, in The American Biology Teacher, Vol. 23, No. 6, October 1961, pp. 331-346.)
For a short biography of Hermann J. Muller, click here.
Comments