Intermarriage with an extraterrestrial sentient species

This is going to be one of the weirdest questions I have ever asked concerning marriage and sexuality…

Say that we stumble upon a planet inhabited with life. There is a sentient alien species distinct from us (homo sapiens) living on that planet. This species has human-like intelligence, has a concept of language, perceives that there is good/evil, etc. (Basically, they act just like us.) In addition, they can produce hybrid offspring with homo sapiens which are healthy and behave just like any one of us.

My question is: What would the Church’s stance be on our interactions with this new species, should something like this happen?

This question has been burning in my mind, even before Pope Francis made his homily on baptizing Martians.

Well the two cannot become one flesh as the human and the alien are not “bone of my bone, and flesh of my flesh”, therefore there can be no sacramental marriage.


I’m not certain that the “bone of my bone, flesh of my flesh” point is the salient point in the determination of the sacramentality of marriage.

Let’s ask this question: when God removed Adam’s rib, could He have created a horse from it? (Of course He could.) Would that horse then have been “bone of [Adam’s] bone, flesh of [Adam’s] flesh”? Well… yes! Would that horse have been a candidate for sacramental marriage? Of course not.

It would seem that the notion of the imago Dei – that is, being created “in the image and likeness of God” – is more relevant to the question at hand.

A valid marriage can only be contracted between a male and female person. A sacramental marriage – which is the question you’re asking – can only be contracted between Christians. So, if an alien could become a Christian, it would seem that he might be a candidate for a sacramental marriage, considerations of ‘bone of my bone’ notwithstanding… :wink:

Guess we’d need to see what these aliens were like, have a few more specifics…lol :smiley:

God didn’t create a horse, He created a woman.

God didn’t choose other clay to make the woman he chose the rib of Adam - bone of my bone, flesh of my flesh.

We can only have sacramental marriage with a human female (if male), or a human male if female.

Otherwise why is the Church arguing against gay marriage?

Marriage is a sacrament in the order of nature.

If nature didn’t intend it then it ain’t marriage whether the participants are Christian or not.

There are many deeply Christian gay people, but they cannot be sacramentally married to someone of the same gender.

IMHO, guess it would depend on how humanlike they were. For example, if they looked liked lobsters, then I would say no. However, if they were pretty close to being human in every way, then IMHO, possibly yes, after they had accepted baptism.

Marriage is a sacrament in the order of nature: that means the union must be natural.

Men and women can look fairly androgynous, and therefore similar, but even so men cannot marry men and women cannot marry women.

Nor can they marry primates even if they are female, or monkeys etc etc etc.


Let’s reexamine the OP’s question in light of what I highlighted from the quote above.

  1. the OP question assumes that an alien and human inter-specie couple can have fully functioning offspring.

  2. on earth, there are NO two animal species which can have crossbreed and have fulling functioning offspring. Horses and donkeys come close, but two mules cannot naturally breed. Therefore, a horse & donkey cannot have fully functioning offspring.

  3. humans were made in God’s image.

If there is an alien species out there which humans can successfully mate with, without artificial tampering (DNA tampering, etc) then nature is allowing it.

If nature allows it and the alien becomes a baptized Christian, then would be something within God’s plan.

If we meet intelligent alien life, it will ONLY happen because its part of God’s plan and will.

Here’s another way to look at it: if God created the universe (and physics) with a way to create warp drives or travel through wormholes; and IF the aliens we meet have DNA so close to ours (if not identical) that we can actually interbreed; then how could that not be God’s will? If we have to travel 100s or 1000s of light years to find a species to interbreed with, because we can’t do it on earth; then that sure seems like intelligent design to me.

Food for thought.

Male humans cannot marry female monkeys for the same reason male humans cannot marry other male humans… The natural creation of fully functional offspring is not possible.

But the OP’s question assumes that creation of fully functional offspring IS naturally possible.

Huge difference


You go to the top of the class!!

Elaborating further - A creature cannot create fertile offspring with another creature unless both creatures are of the same species. In fact, I’m pretty sure that’s one of the ways biologists define different species.

A horse and a person cannot create offspring together at all - horses and humans are different species. A horse and a donkey can create offspring together (mules) but this offspring is infertile - therefore we can tell that horses and donkeys are also different species.

So technically if these other beings were exactly like us and made fertile offspring with us, we could class them as being in the same species i.e. human. And therefore marriage wouldn’t be a problem. :twocents:

We won’t!

Incorrect. Mules mostly cannot naturally breed, but there are isolated but scientifcally verified instances of this happening.

In the plant world there are plenty of examples of hybrid species. In fact much of our food is made of plants that were originally hybridized from different species of wild plants.

Recent paleontological research shows that early humans interbred with neanderthalers and that there is probably some neanderthal DNA (albeit strongly diluted) in the majority of humans alive today.

There are species that have lost the ability to reproduce sexually. They only produce offspring by producing clones of themselves. If being able to mate and produce fertile offspring was part of the definition of a species, then surely every individaul of the above species ought to be a species unto itself.

Also, as I said above, there are exmples of inter-species hybridization. Lions and tigers for example can be crossed although they are distinct species.

I meant more that it’s one way to determine whether a creature is the same species as another creature.

Lions and Tigers can be crossed but their offspring is generally infertile too I think. Like mules.

Truly, the weirdest post I’ve seen on here.

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