Recently I read a news item about a crusade to ban slaughtering horses in the United States for human consumption. My first reaction was, "Huh? Who in this country eats horsemeat?" It turns out that some slaughterhouses in North America supply horsemeat for foreign markets. Eating horses, not to mention dogs or guinea pigs (the latter were originally domesticated as meat animals), strikes us as repugnant. As Steven Pinker mentions in HOW THE MIND WORKS, most of us eat flesh from only a few animals and, from that small group, only certain parts of the creature's body. Cultural squeamishness prevents us from taking advantage of a wide variety of perfectly nourishing protein sources. Not that I'm complaining; I share that squeamishness. (I once tried in good faith to eat a soft-shelled crab. I had to stop after one bite, since the texture struck me as not unlike a giant insect.) Pinker has a valid point, though.
Americans embrace and enshrine in law some few cultural taboos that have no readily identifiable secular, civic justification. A couple of examples immediately come to mind. Not that I personally endorse these practices—I simply propose that banning them doesn't necessarily have a rational basis.
Speaking of eating animals, what about animal sacrifice? To most Americans, the phrase conjures images of dark, savage rites. Until the destruction of the Jerusalem temple in A.D. 70, however, animal sacrifice played a central role in virtually all the world's religions. Since the meat of sacrificial animals is eaten, the practice effectively amounts to a different, more intentional and reverent way of preparing animals for food. If performed with as little pain as possible, why should it be illegal? Animals killed that way probably suffer less trauma than those herded into a slaughterhouse.
Changes in sexual mores and marriage laws often evoke cries of alarm from some people that we're sliding down the slippery slope to all kinds of dire outcomes, including legalized polygamy. But polygamy was also a widespread custom through most of Earth's history and remains legal in many countries today. Why shouldn't it be?—among consenting adults, needless to say. The only valid SECULAR reason I can think of to ban that marriage structure is fiscal. Social Security and health insurance for additional spouses would have to be funded. That problem doesn't seem insurmountable, though. Such programs cover multiple children. With minor adjustments, they could cover multiple spouses (for increased premium payments, maybe.)
When we meet extraterrestrial aliens, we'll probably encounter customs that seem as appalling to us as, maybe even more than, the practices of "primitive" cultures on Earth appeared to European explorers. For example: Most of us consider it an ethical obligation to use heroic measures to save the lives of premature babies. (The word "heroic" itself reveals our feelings about this issue.) In a hunter-gatherer society, a newborn infant too small or sickly to survive (given that culture's level of medical technology) would be left in the forest to die quickly rather than linger for days or weeks and then die anyway. A mother who refused to "expose" such a newborn wouldn't be praised for her devotion; she would be censured for subjecting the clan to a futile burden.
In Robert Heinlein's STRANGER IN A STRANGE LAND, Mike (the human castaway brought up by Martians) tells his new friends on Earth that in Martian society competition for fitness to survive occurs at the beginning of life, not in adulthood. Martian "children" past the hatchling stage are relegated to the wilderness to live or die on their own. In this novel, also, characters propose a favorable view of group marriage and ritual cannibalism. In THE DARK LIGHT YEARS by Brian Aldiss, Terrans discover aliens that make nests of their own dung. This species is intelligent, but the Earth scientists don't know that. They provide the creatures with clean, sterile environments in a well-meaning attempt to improve their health and living conditions. The aliens sicken, because their symbiotic relationship with the lower animals that live on their droppings is essential to their well-being.
Imagine meeting intelligent ETs who devour their spouses after mating, like praying mantises and black widow spiders. There's a major challenge for a romance writer! Or a civilized species in which babies eat their way out of the mother's body, like some Earth spiders. In that culture, a female who manages to survive the birth of her offspring would be an object of scandal. Octavia Butler's "Bloodchild" features human-size, centipede-like sapients who've made a deal with Terran colonists: In exchange for being granted refuge on this planet, some human hosts allow eggs to be laid in their bodies. If all goes well, the larvae get removed immediately upon hatching, and the host (usually a young man) survives unharmed. Sometimes, though, things don't go so well. . . .
Margaret L. CarterCarter's Crypt