Fixated on the Local Flavor

So some dude over on Creative Minority Report posted something about "Did Jesus die for Klingons too?" Now that is a question that is of interest to any theologically alert science fiction writer, but it requires a bit of backtracking.

Unfortunately, our definitions in biology, despite their detail and subtlety, desert us near-completely when we begin to speculate about alien life. Animals, for instance, are defined by modern biology as "eukaryotic organisms whose development entails a fixed body-plan, although they may undergo metamorphosis, all of which must consume other organisms to survive". Plants are variously defined, but tend to be "a group of organisms that possess chlorophyll a and b, have plastids that are bound by only two membranes, are capable of storing starch, and have cellulose in their cell walls"; frequently the definition is expanded to also include those plants that use engulfed cyanobacteria for photosynthesis—although, like mistletoe, there are plants that can't photosynthesize.

But what about on alien worlds? Aliens, I regret to inform writers, are simply not going to be 100% identical with terrestrial life. We have to fall back on a much more basic distinction, something like "flora and fauna". Flora are the non self-mobile life that produces food from energy, i.e. by photosynthesis (or absorbing the heat of underwater lava rifts). Fauna are the self-mobile life that gets energy by eating other organisms, either flora or other fauna.

The reason we need to use that distinction is, SF (and non-artistic exobiological speculations) ought to avoid unnecessary assumptions. Assumptions involved in the word animal, for instance, include "has DNA" and "is eukaryotic". But it's possible, if not indeed probable, for other planets' biospheres to use some other complex molecule for genetic encoding. And, while complex alien life is likely to have cells with organelles, especially nuclei, it is unlikely in the extreme that they will all map one-to-one to terrestrial ones. Mitochondria, for instance, are members of another kingdom absorbed by the first animals' cells. It is entirely possible that an aliens' cells might have a cisgenic¹ organelle that performs the same function.

Plants, similarly, might use any color of pigment, bonded to any particular type of cells, for their photosynthesis. While something analogous to cellulose is highly likely, because photosynthesis requires fairly immobile structures that can sit in the sun for long periods, and sugars are probably how any organic life-form would store the product of photosynthesis, it's not impossible that a plant might make its cell walls from protein or even a hardened lipid (cell membranes are made of lipids, after all). Hell, it's not inconceivable for a plant to take a sponge-like approach, and make its rigid structures out of silica—which would create some scary herbivores.

For the other couple kingdoms, bacteria, protists, fungi, and "freaky things that only exist to irritate scientists", all bets are still more off. A world could have multiple "flora" classes with photosynthetic properties—actually, Earth does, algae isn't a plant—or multiple "fauna" ones that don't. A world's "mushrooms", for instance, might actually be "sponges", members of the fauna kingdom that have evolved to a sedentary-scavenger condition. There are likely to be "virus" analogs everywhere, but they might be more traditionally "alive" than our viruses (something like a parasitoid bacteria that uses the host cell's nucleus like a microscopic tarantula hawk, for instance), or they might be genetic-drift inducing toxins, even less alive than viruses are.

I'm not sure how an SF writer should refer to such things. "Plant" and "Animal" are fine, I use them myself; and my felinoids call an invertebrate with a segmented exoskeleton "a bug", even though theirs have 8 legs and usually only 2 wings, if any. You could also go with "autotroph" or "heterotroph", or as above, "flora" and "fauna". But remember not to assume. My felinoids' trees, for instance, come in two types: something like yews or other conifers with leaves, but they flower and their seeds are inside fruit rather than cones (and yes, I did consider using arils as their equivalent of fruit); and something like a cross between seaweed and an agave, whose branches, rather than leaves, are their photosynthetic part (like earthly plants that use that strategy, they have spines to ward off herbivores, the reason being that leaves are much more expendable than "a limb"...which come to think of it is probably why desert plants that have leaves are also more likely to have spines, their leaves are much less expendable). Their ground-cover isn't grass, but something that looks a bit like clover (related to the former type of tree). Their grain-like plants have some things more in common with legumes, like the seeds being in pods. And none of their vegetation is green, but brownish-purple or various shades of red or orange.

It is something of a challenge to keep from writing "fish" instead of "aquatic animal" or "bird" instead of "flier", but I enjoy trying to scrub as much terrestrial content while still remaining comprehensible (that second thing is why I still say "animal" and "plant" and "bug" and "tree").

PS. So what about the issue that started all this, whether Christ came for Klingons? Well, metaphysically, all sapient animals are "man", so what saves "man" saves all men, no matter where they're from. The same principle also, incidentally, answers the question of whether aliens have "human rights"—since rights are metaphysical, and they are not metaphysically different from any other "man", they have the same rights.