So, a visitor (whether they be from another planet or another reality) gets deposited on the face of the Earth. They find that the air's breathable, that water and suitable macronutrients are available, and that there are signs of sentient presence (us!) on this planet.

However, between:

  • Their inability to communicate fluently with the humans who they encounter
  • And their inability to pass for a human under cursory examination

they are taken in to a research hospital for evaluation. What evaluations and tests would be performed on them?

We can assume that our visitor:

  • Can't return home or bring more friends over
  • Doesn't have an alien/otherworldly biology text/set of texts with them for us to study
  • Is a carbon-based, aerobic, chemohetrotrophic life form -- their body can process Earth macronutrients (albeit perhaps with some difficulty), and does not need any micronutrients that cannot be obtained from Earth-food
  • Is sentient, and has intelligence roughly comparable to an average human (within 2 sigma of the human average, certainly), as well as having vocal cords
  • Has a bipedal (roughly humanoid) body plan, with plantigrade locomotion and opposable thumbs
  • Does not have to concern themselves with human diseases, and cannot transmit any diseases of alien origin to us
  • Is in good physical condition, with no serious heritable disorders
  • Is docile and understanding regarding our obvious curiosity, and wants to understand us in return -- obviously, they'd rather be alive than dead, though, and probably would react badly to us trying to kill them.
  • May have subtly different biochemistry to us -- not enough to make Earth uninhabitable long-term, but the possibility exists that, say, blood tests may return odd results.
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    $\begingroup$ Every test they could think of! $\endgroup$ – JDługosz Feb 4 '16 at 0:24
  • $\begingroup$ The real factor is: do their friends know he is here? as in "Wfrdrx? No, nobody came with that name. Never. So it was not us who killed him trying to get more information out of him. Have you asked for him in Mars?" $\endgroup$ – SJuan76 Feb 4 '16 at 0:53
  • $\begingroup$ @SJuan76 -- the answer to that is "their friends know they would be gone for a while, but no, they don't know our traveler's whereabouts" $\endgroup$ – Shalvenay Feb 4 '16 at 1:28
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    $\begingroup$ this is actually a REALLY original question, I would love to see some insightful answers to this. +1 But like JDlugosz says, probably every single test to prove that you ARE human would be carried out. $\endgroup$ – fi12 Feb 4 '16 at 1:32
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    $\begingroup$ Why are there always people who immediately say the humans automatically slay the aliens? They are worth so much more alive! Interrogate them, interview them, but don't kill them! Seriously, killing the creature is the worst way to go. $\endgroup$ – Xandar The Zenon Feb 4 '16 at 3:14

Obviously, people want to talk to this creature, and examine him in many different ways. We're not barbarians, though, so assuming this alien get in with the more decent science-y folk, here are some of the things it would undergo:


That's right, functional magnetic resonance imaging would be the first test for the budding xenobiologists. It's non-invasive, but gives us so much information about the alien's body structure without offending our visitor. Even better, we can copy those results and send them to everyone who is interested in the alien! As a plus, I feel like it's the first place to start learning about the alien's body; it gives the big view (and also some very small views!).


Venipuncture is a blood draw. This assumes there is something like a circulatory system in our little extraterrestrial. This will let us know about their immune and circulatory system plus any other things which are there that we don't find in earth-creatures. (Stuff like the nervocirculatory system of the Krogan from mass effect!)

Ideally, you would have the alien get their blood drawn after seeing someone (or multiple people) getting their blood drawn, so it knows that this is OK. Depending on the willingness of the alien, this could happen multiple times.

Linguist Hook-Up

This isn't a formalized test, but figuring out the language of the alien and establishing communication would make things so much easier. So we need someone who knows about languages Ideally this would be a team of polyglots and linguists.

Seeing as our visitor is curious about us, too, this seems to be the best way to go.

After These Tests?

Once the avenues of communication are available, we get to move on to studying the sentient part of the sentient alien. We can ask questions like "where did you come from?", "what is your culture like?", "Sunny side up or over-easy?", "may I take your picture?", "which transmission from earth did you receive first?", "how did you get here?", etc.

Once communication is established, we act like he's a special diplomat, because we just never know if Humanity is on Trial. The first book he writes not only makes a publisher filthy rich, but also secures a life-long income for our visitor. Even if this alien is a space redneck, it's all we got, so what it says flies.

  • $\begingroup$ Bonus points: I wonder if the visitor's ever seen his own people's insides on a MRI before... $\endgroup$ – Shalvenay Feb 7 '16 at 22:24
  • $\begingroup$ "We're not barbarians, though" -- well, some humans are more relaxed about waterboarding than others. $\endgroup$ – Steve Jessop Feb 3 '17 at 9:52
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    $\begingroup$ @SteveJessop Waterboarding? No, I think some thermometer, stetoscope, X-ray, blood pressure cuff, USG, EKG, EEG(?) etc should be tried first. Waterboarding is superfluous, if Americans want to crush will of such being, all they have to do is run a series of medical test and hand it a bill. $\endgroup$ – Shadow1024 Apr 27 '17 at 18:36

I suspect it depends a lot on where and when.

There's a few considerations in general which our visitor might not like.

Xenobiological contamination works both ways. We need to work out if the life form might pose a threat to humanity inadvertently. It could result in a outbreak similar to when the europeans settled in the americas, or mean nothing. Or the common cold would be lethal to our visitor.

As such, frustratingly, we'd need to put our guest in quarentine until we know for certain we arn't going to accidentally kill each other's species with a sneeze.

Working this out? We'd likely want all the bodily fluids we can get. Poop, piss, blood... Even other biological secretions.

We'd also want to get the psycology of our visitor. Depending on whether they're seen as a threat, this may vary wildly. We've actually done a decent job teaching non human species baseline understanding of our languages and members of our species who speak other languages, so getting a baseline communication method could be possible (though way out of my ability to SWAG into an answer.). Consider the great ape language experiments. A intellgent species with the ability to communicate verbally the way we do might actually find it easier, and what they don't know, in terms of objects and symbolism is as useful to us as what we know.

Hopefully we don't get someone too belligerent, and have them decide that the visitor is a threat and try sleep deprivation and other tortures.


Primary flaw in this presentation:

It would take a lot, a lot, a lot, a lot, I mean, man, A LOT, A LOT AND A LOT of luck for an alien life form to be so much compatible with our molecular life structure.

Their body is a telltale sign of potential mucho troublo: 'roughly humanoid' is too broad, but it tells us that they didn't necessarily evolve from primates like we did. They could be descendants of squirrels! Or from rats! Are they mammals or reptilians? Do they lay eggs and brood them or they gestate? Their basic dietary needs may vary greatly if they are mainly herbivores or more canrivorous than we are. Dental examination will be in order, for a start.

All of this to tell you that the slightest variation in DNA -that is, assuming they have DNA at all!- will make a lot of stuff from our world toxic to their methabolism.

They can breathe our air, but are we sure they can breathe the exact same gas mix?

Also, if they come from a world that finally got ridden of old pollutant technology, they'd be getting lungfuls of cancer by just moving in a city. Pollen in open country could be easily clog their respiratory apparatus

Their best hope is that they know they must call for help, hiding is out of the question. If they are stranded and knowing they're on a short fuse before any kind of sickness or poisoning kills them they must go to a hospital. But they cannot just be wandering around ("This people don't even have maglev cars! Their exhausts are chocking us!") so they should eventually, after deteriorating conditions win over panic, go to any house and somehow explain they need medical attentions.

In a hospital, they'll be x-radioed, scanned (hoping their methabolism is not too sensible to these noninvasive exams), EEGed, EKGed. They'll be given sterilized water to drink. As for food, hopefully they have the equivalent of K-rations packs so that biologists and nutritionists can create at least a nutrient sludge for them. Funny enough, needles will be the last resource to be used: I mean, these are true-than-life extraterrestrials, world's greatest discovery since prehistory! A responsible doctor wouldn't want to risk to insert ambient contaminants straight into his patients' blood flow.

And no, sorry, superimmunity can't be a thing here: a living body, per definition, hosts a microbiotic plethora. One can scrubs himself into sterylization outside, but inside antigens, intestinal flora, our tiny army of good health works 24/7 to keep us in terrific shape. Without those, the external agents will kill us. The aliens either are robots or as living thing they are at risk of exposition -and, again, immunity to most disease is not invulnerability to chemical exposures.


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