When your deep-space probe finally lands on GX598 and you step out, what sort of creatures will you see? The pundits have proposed aliens both large and small, agile runners or plodding hulks, creatures with two legs, four legs, or more. But one of the most critical characteristics debated by the experts is body cover. When we finally meet up with intelligent life from on high, will the species we find be smooth-skinned or furry, covered with downy feathers or flat, bony plates? It all depends on the environment of the alien planet. But given the laws of evolution, it seems likely we'll find some of the same outer body characteristics already found on creatures of the Earth.
Many people argue that since extraterrestrial life is genetically unrelated to us, extraterrestrials will look nothing like us or anything we can imagine. That argument is based on the assumption that our form is strictly genetic, and that it results only from chance mutations. If, on the other hand, much of what we are is rooted in logical and physical laws, then those laws may turn out to be universal and may constrain aliens in the same way and to the same extent that we are constrained. If that's the case, we may be able to make some very solid predictions about the way intelligent aliens will look.
One example of a feature that might be under strong constraint is body cover. Any alien, no matter where it lives and no matter what its shape (as long as it has a shape), will have a point where the individual ends and space begins; in other words, the individuals in an alien species are likely to have a body surface.
It is also reasonable to assume that an alien will have some sort of developmental scheme--that is, that it developed from a simple form into something more complex. What is true for the alien as a whole must also be true for its body cover. Early in its development, alien body cover must have been flat, the simplest form it can attain. Then, in accordance with physical laws, the alien skin could have become more complex through time.
In becoming more complex, skin has only three choices: It can remain flat; it can thicken or fold out (evaginate), forming structures such as feathers or scales; or, it can fold in (invaginate), giving rise to hair, teeth, claws, or nails.
There are many reasons why animals develop hard dermal appendages: These structures aid in sensory preception, protect the organism, and help to regulate body temperature by acting as insulation. Indeed, just as in a house, the better the insulation, the less the energy required to maintain a constant temperature. The importance of thermoinsulating appendages is particularly clear in light of the fact that they have evolved independently here on Earth several times among terrestrial organisms. Look at the panoply of Earthtly life, and you'll see an abundance of insulating feathers and hairs.
So, travelers to GX598, stand prepared! When we encounter that alien, it is likely to have a body cover resembling skin. And, unless its world is unusually hospitable, we're also likely to see a combination of fur, feathers, nails, teeth, and scales.
COPYRIGHT 1993 Omni Publications International Ltd.
COPYRIGHT 2004 Gale Group