I have traveled the galaxy and experienced dozens of worlds with intelligent life and civilization. I’ve been to freezing deserts, baking deserts, water worlds, jungles with ferocious predators, those whose inhabitants dwell in caves, and several Gardens of Eden with entirely pleasant surroundings. I’ve been in orbit around some worlds with very high mortality, but prudence dictated I stay in orbit. In a couple, lifespan follows an exponential decay curve, so there are a few who are thousands of years old, more who are hundreds, and a great many children and young adults.

I’ve seen many strange customs and many strange social arrangements. I’ve seen societies of extreme inequality. In one there is harmonious cannibalism where a higher caste routinely kills and eats members of the lower caste -- who understand their role in the society and accept it with equanimity.

But the stories I tell today are of societies with sexual arrangements that to us will seem very strange.

Imagine a world where women have sex only once in their entire lives, during a brief “heat” with a single man, and store the sperm and use it for all their pregnancies.

Imagine a world where they have sex all the time, and women get physically ill if they don’t get it regularly -- and imagine the opposite where it is men who must be constantly mating to stave off aging and death.

Imagine a world where it is only at the end of life, around age forty, that women have sex, and then they grow enormous during pregnancy and must die as they deliver between three and ten babies who are then raised by others.

Imagine a species that has evolved in tandem with a domestic animal somewhat like a goat. The humanoid males mate with and fertilize the female goats, while the male goats mate with and fertilize the humanoid females. The humanoids subsist entirely on goat milk, while the goats are protected by the humanoids from fearsome predators. The humanoids view the goats with contempt, and no one knows what the goats think.

But I will focus on just a few stories in greater depth, stories with people who are very much like us in most respects, and the few differences will hopefully intrigue you and resonate with you, my reader.

The galaxy is very large, and the wonder and variety to be observed among the intelligent species is stunning.

1. The agony of getting pregnant

I asked how they made babies, and a married couple volunteered to show me. They had two children but wanted another. Anyone could tell when a woman was fertile by the smell, and I could too. I asked how likely it was that this act would result in conception, and they told me it was almost a sure thing, 90% or so.

The wife said that the man should tie her up, and no matter what she said, not let her go until he had finished impregnating her. The naked woman cooperated as he tied each of her wrists and ankles to the four different posts at the corners of a bed.

The man’s erection appeared and he entered the woman. She winced. I could see her biting her lip and struggling not to cry out as he thrust into her with enthusiasm. After a couple minutes he groaned and held himself deep, looking just like one of our human males when he ejaculated. As he did, the woman yelped. The man withdrew, cock shrinking.

I thanked them, thinking it was pretty tame -- no worse than house cats on earth, perhaps. But they smiled and said they were just getting started. It would take about 12 hours in all. The man busied himself with other activities and the woman lay on the bed, watching a TV on the wall. After half an hour the man returned with something like a milkshake that the woman drank. And then his cock got hard and he entered her again. The woman yelped again and cried while he thrust away, shrieking when he ejaculated.

The man appeared each time with a beverage. At the fifth time, the woman refused it and said she couldn’t stand the pain and he really ought to untie her. Two children was plenty. But the man didn’t. He mounted, and as she cried and writhed he thrust into her harder than before. When he came she gave a full-throated scream. She ask that he turn off the TV, and with this request he readily complied.

Every half hour or so he appeared again and ignored the woman’s pleas to be released. He penetrated and thrust hard to the point of violence. If he paused the woman relaxed visibly, but when he went back to thrusting she convulsed in pain.

Eight hours on, the woman begged for mercy as the man disengaged. I followed him out of the room and asked how it was for him. He grinned sheepishly and said there was nothing quite so hot as a screaming woman in heat. Other times, when the woman wasn’t fertile, they had sex, she had orgasms and it felt OK to him. But this was magnificent. Didn’t it bother her that she was so upset? Yeah, kind of, he said, but there was no other way to make a baby.

The man reappeared to screw his mate more frequently. By ten hours he was doing her every ten minutes, penetrating her deep, thrusting hard and fast and coming after about two minutes, followed by eight minutes of catching his breath. Whether he was resting or copulating, the woman kept pleading with him to stop and let her go, but he didn’t. Blood was oozing from her vagina now.

After about eleven hours he entered her once more and told me over his shoulder that this was the last time. The woman groaned at the announcement and then he started humping away. This time he didn’t come after a few minutes but just kept humping and thrusting and rutting as the woman kept moaning and crying and occasionally screaming. And then at last, after his thrusts got even faster and more insistent, he lunged deep and help still. I got to see the contrast of his face relaxed in ecstasy as hers was scrunched up in agony. They held that position for a full minute before the man finally withdrew.

It was a stunning display of male power and female subjugation.

He didn’t untie her right away, he explained, because sometimes women got violent until they had more time to calm down. She fell asleep and only woke up a little when he untied her.

And then -- she thanked him! They kissed.

I asked if their women ever got pregnant without being restrained, and they said no woman had ever succeeded at that, though a few had tried. Some men subdued the women with physical force, but no threat was enough to make a woman keep cooperating during the act.

I asked about pregnancy and they said women felt good when they were pregnant. I explained the morning sickness our women typically experience, and they thought that sounded weird and awful. I explained the aches, pains, and weariness of late pregnancy, and they said there was none of that. Everyone knew a pregnant woman felt great.

Later they said a woman they knew was going to give birth, and asked if I’d like to attend the labor and delivery. This was a party, with friends and relatives invited. Every time there was a contraction the woman moaned with orgasm and people cheered her on. As the contractions got closer together the orgasms got bigger. In the pushing phase the midwife reminded her a couple times to push instead of just relaxing in afterglow, and the woman with a sheepish smile did. She was working hard, heart pounding during the contractions, but what she felt was ecstasy. At the final push she cried out, and the women present sighed, some remembering how absolutely fantastic it felt when they had given birth, others looking forward to the day they could experience it too.

When I thought about conception on the one hand and the birth process on the other, I realized that the women experienced less pain overall to have a baby than we humans did. It’s just that their pain was all at conception, while human women suffered various forms of unease during pregnancy and then had plenty of pain during childbirth.

When I described how things worked with humans they were horrified and said they’d never choose that instead.

2. Desiring a woman is sick

The scientists explained that in their species pathogens such as viruses, bacteria and fungi have been a strongly driving force. Sex among animals on earth was a response to this problem, and here the response is even more dramatic. Females collect in their uterus the semen from many men, and through a complicated process involving their own immune system and the pathogens they are exposed to, they create the genetic blueprints for future babies based on their own DNA, then mixing and matching from the genetic material contributed by dozens or hundreds of men. Having many years to try out different combinations is a real benefit, so their girls were wired to start collecting semen not long after they turn 3. The process is complete by the time they undergo most of the changes we associate with puberty around age 13 -- larger size, breasts, and wider hips, all geared to actual pregnancy and childbirth. But their eggs are all “fertilized” (speaking loosely) by puberty. Their genetic make-up is fixed and so the women have no use for semen. So naturally the species has evolved so that they have no interest in sex and men have no interest in having sex with them.

All the long-lived land creatures on the planet use this method. The rough equivalents to our rodents use the same method as we earthlings do, so they are familiar with the concept but it naturally is seen as primitive.

Little girls feel sexual pleasure based primarily on how genetically different the sperm is from what they have already collected. They are therefore strongly attracted to men who look different from them and who smell different. It is common for groups composed of well-off uncles and nieces (there are no identifiable “fathers”) to take extended world tours to regions where people look different. The local little girls are very interested in the uncles, and the little niece tourists can be deliriously happy collecting dozens of exotic semen samples a day if they choose. (The girls only keep the genetic material, and the semen flushes out within a day as a vaginal discharge.)

Though a member of a different species, I was apparently still “human” enough to attract their interest and in fact was the ultimate in exotic. During my visit I was besieged by small girls. I wondered if my genetic material might be so different as to be harmful, but their scientists scoffed at the idea. Their little girl uteruses would have no trouble sorting out any genetic sequences that didn’t belong.

Once I explained our mating habits, they understood intellectually why I resisted the advances of the little girls, but it was hard for them. Many a preschool girl was taken from my presence in tears. The mothers offered the explanation that I had just given my sperm to other girls so there was virtually none left, but it mollified them only a little, as even a tiny amount of very exotic genetic material is valuable.

I decided to participate in the culture as best I could, which is of course part of our training. The bigger girls, presenting their rear end to me for a doggy-style mating, were sufficiently attractive that I could perform. The first one’s vagina gave superb pleasure beyond anything I have experienced on earth. The reaction of the girl after I was done delivering my load was extraordinary. She fell to her side, moaning, groaning and twitching, with an ecstatic smile on her face. She then passed out, but shortly regained consciousness and the pleasure lasted days.

As the experiment was a success I was naturally interest in participating further in the culture. Yet I confess that the extraordinary vaginal welcome interested me inherently, and I started doing a girl a day. Although I tried to be open-minded, I could not manage an erection for the act with any girls younger than nine or ten, despite my best efforts.

They were surprised to learn that we usually insisted on having sex in private. There, little girls and men copulating in public spaces was noticed less than two people kissing would be here. But with an exotic man like me, there was much interest in watching if we did it in public, and eventually dozens of people were crowded around for each copulation I performed, and it was often captured on video. Perhaps I have an exhibitionist streak. The girl’s mother, aunts and adult sisters were so delighted by the prospect that my natural revulsion at what here would be committing sexual abuse was greatly reduced. Younger sisters were kept away, as they would be strongly envious and frustrated that they weren’t benefiting from my sexual attentions instead.

When I first explained that in my species men wanted sex with adult women and had sex with them, the audience was uncomfortable. When I cheerfully added that I found many of their women attractive, that was apparently too much. One woman abruptly left the room, another gagged and the men looked horrified. They said some things are just too serious to joke about. From then on, when the subject of our world’s sexuality was introduced it was preceded by a rough equivalent of a trigger warning, and the horrible idea that I personally might in my mind entertain thoughts towards the adult women on their planet was not mentioned.

For as in our world, there are perverts. There are men who do lust after grown women and a few who rape them. While no one defends such rape, their scientists try to explain that the attraction these strange men feel to adult women is inborn and can’t be changed, and that it’s better if such men are accepted so they can be given help to make sure they never do rape women. But it is a very hard sell, and I read many opinions as to why such attractions are evil and such men should be killed. The purpose of sex is reproduction and no such matings can contribute. Past puberty, vaginas serve only as an exit conduit for babies. (In response to a privately posed question, one open-minded, gentle scientist confirmed they are also dry and unsuited to receive a penis in any comfort.) To them it is obvious that once a woman grows hips and breasts her body has moved to the phase of bearing and nursing children, and no sane man could find her sexually attractive. Those few women who were raped were in fact terribly traumatized by it.

There are also a very few young girls whose vaginas are still small at the age of 4 and who do not welcome male attention. Such girls are considered to have a shameful and serious condition, though of course their mothers still do their best to love them. I was fascinated to learn that their ovaries are always removed at the start of puberty. Otherwise a few of them at least would develop sexual interest in men. That is too horrifying for the society to contemplate. A few wild-eyed radicals suggested that if these girls developed into such women they could serve as a safe sexual outlet for those few men who are attracted to adult women. Such a view is considered only slightly less crazy than the idea they should cook and eat their little children for dinner.

We who land on other worlds know we may not survive. Local diseases may kill us, or we may run afoul of local customs we do not understand. In this case the problem was arranging to leave after a year. I was just too valuable to them as a source of new genetic material. When I figured out that they were making excuses to delay my departure, I said I would refuse to have sex with any more of their girls. Eventually we reached a compromise. I would provide a month’s worth of semen samples which they could then divide into tiny doses and insert in hundreds of girls by artificial insemination. Some could be kept frozen for future use. That and a few seminal bribes to the nieces of key bureaucrats (and daughters of those who were women) were enough to get me back to my spaceship in orbit.