Would Aliens be under the Kingdom Animalia?

[Beleriphon]

Or, if you want to get more sciencey, Xenofauna.

I would say that xenobiology would belong to a different tree. The tree of life is things that stem from a single (or incredibly close groups) of life, and alien life would simply not be connected to it at any point. An alien life form that does horrifying Alien stuff could have the Earthling "morph" be considered to be on the tree, but the original species itself would not.

Maybe, but if the root is Life we add a branch for Earth, and then another one for Tau Ceti. In theory both branches include Life as the most basic structure on such a tree.

Or it could turn out that the theory of panspermia is correct, and we actually are related to those things on Tau Ceti.

[Radar]

Maybe, but if the root is Life we add a branch for Earth, and then another one for Tau Ceti. In theory both branches include Life as the most basic structure on such a tree.

Or it could turn out that the theory of panspermia is correct, and we actually are related to those things on Tau Ceti.

It would make only sense for panspermia, since for two different abiogeneses (is it a correct plural?) there is no connection whatsoever, so there is no common root - far better to to talk about life forest with completly independet trees instead.

[veti]

Even the assumption that alien - things will be readily and recognisably divisible between "living" and "non-living" - let alone between such specific categories as "animal", "plant", "fungus" etc. - seems to me to be taking a lot for granted.

[Jay R]

We cannot begin to answer this question until we see the aliens.

Evolution might be sufficiently parallel that they seem to be closely related to animals. Or they might be clearly and unambiguously plant-based. Or they might be something totally different in a category that we (obviously) have no experience with.

Perhaps instead of being carbon/water based, they are silicon/methane based.

It took a long time for us to classify birds and dinosaurs together, and they're earth-based.

But since the hypothetical aliens didn't evolve from the same primordial soup that we did, and everything on earth did, they are probably more chemically and biologically different from us than we are from mushrooms, coral, algae, fleas, or green slime mold.

There's no way to know how to characterize a structure without knowing anything about the structure you are characterizing.

[Lvl 2 Expert]

It took a long time for us to classify birds and dinosaurs together, and they're earth-based.

Which is why we grouped them together based on common ancestry, the same logic used to create the kingdom animalia.

Aliens presumably being alien would not share that ancestry. At best they're related through very primitive spacebourne ancestors, which would not have been birds or dinosaurs.

[Tvtyrant]

Which is why we grouped them together based on common ancestry, the same logic used to create the kingdom animalia.

Aliens presumably being alien would not share that ancestry. At best they're related through very primitive spacebourne ancestors, which would not have been birds or dinosaurs.

That is when we find out that there are tiny portals throughout the galaxy, and all life descends from baby crabs and other tiny organisms slipping back anf forth.

[LibraryOgre]

That is when we find out that there are tiny portals throughout the galaxy, and all life descends from baby crabs and other tiny organisms slipping back anf forth.

Or ancient aliens, seeding their DNA across the galaxy.

[Tvtyrant]

Or ancient aliens, seeding their DNA across the galaxy.

It is what I would do to be fair.

[Jay R]

Which is why we grouped them together based on common ancestry, the same logic used to create the kingdom animalia.

Aliens presumably being alien would not share that ancestry. At best they're related through very primitive spacebourne ancestors, which would not have been birds or dinosaurs.

Yep. Based on our knowledge 100 years ago, we had another system. Based on our current knowledge, we do it based on common ancestry. Common ancestry is the most reasonable basis we have for life forms that actually have a common ancestry.

When and if we encounter alien life, we will have an overwhelmingly new bit of knowledge -- a new type of ancestry. If the aliens look like intelligent dogs, or peacocks, or Venus fly traps, and the DNA evidence indicates that they are closely related, then this new information would lead us to new knowledge about evolution, and we will modify our methods accordingly. I think that's highly unlikely, but I have no basis for ruling it out.

I repeat: We cannot begin to answer this question until we see the aliens.

...

I also repeat: But since the hypothetical aliens didn't evolve from the same primordial soup that we did, and everything on earth did, they are probably more chemically and biologically different from us than we are from mushrooms, coral, algae, fleas, or green slime mold.

But that's a guess; we don't know. There's no way to know how to characterize a structure without knowing anything about the structure we are characterizing.

[jayem]

I repeat: We cannot begin to answer this question [sensibly] until we see the aliens.

I also repeat: But since the hypothetical aliens didn't evolve from the same primordial soup that we did, and everything on earth did, they are probably more chemically and biologically different from us than we are from mushrooms, coral, algae, fleas, or green slime mold.

But that's a guess; we don't know. There's no way to know how to characterize a structure without knowing anything about the structure we are characterizing.

Almost seconded, with the modification above. If we (or more usefully S.F writers and Ignoble prize entrists) have these discussions (along with 'human'-rights and the like) we'll be just a bit more ready if we actually have to do it for real. Plus there might be real world consequences (how do we deal with GM creatures? how do we deal with interbreeding/horizontal transfer)

One option that seems to make sense to me (subject to it being useful) would be that similar primordial soups are classified as a 'common' pseudo-ancestor regardless of actual connection. Obviously further back from any specific promordial soup and the almost lifey chemicals where direct descent is meaningful.

So you'd have something like VolcanicSoupia-Aminoacidia-Earthgenesisia(proteins and DNA)-Eukarykote-

But as you said above, that depends on it making sense and being useful. And we can't imagine what the other "branches" might be.

Another option is that we have lots of somethings with an entirely different underlay, but so many examples of convergent evolution that we have to have a system that can cope with that. In one sense that's really easy to imagine "DNAcid-cat", "TNAlco-cat", (in fact you just need to consider 5 equal sized marsupial-esque groups and you'd have incentives on earth. On the other hand cat's are clearly too specific, and we don't really have the words to imagine the groupings there'd be.

[Chronos]

Quoth Bohandas:

There's already two layers above kingdom. First are the "Three Domains" of Eukarya, True Bacteria/Eubacteria, and Archaebacteria. Above that is the division of prokaryotes vs eukaryotes

You have your layering wrong. We eukaryotes are more closely related to the Archae than either us or the Archae are to the Bacteria, which means that the prokaryotes are polyphyletic.