You probably shouldn’t eat ET

Charlie Jane Anders says that if we meet intelligent Space Aliens, we’d probably try to eat them (and we shouldn’t). I agree, because people are horrible, but I also think we shouldn’t because at the least we’re going to get Space Diarrhea, but we’re probably just going to get Space Death.

Anyway, I made a video. Unfortunately, I didn’t script it, but just charged off extemporaneously, which means it ended up about an hour long. Sorry. College professor. Wind me up, I talk for an hour about anything.

The summary: earth life maintains mutual compatibility (more or less) because of its common origin, 4 billion years of co-evolution, and because specialization and cooperation maximizes efficient extraction of resources. Aliens have none of that, and are quite likely to have diverged biochemically in ways that are inherently inimical to our biochemistry, and we have not had any opportunity to adapt to their differences. I also suggest that one hypothesis to explain the so-called Fermi Paradox is that habitable worlds evolve such different detailed chemistries that they are basically tainted toxic soups to other species, and that any sensible starfaring species would flag stellar systems with living biospheres with a great big biohazard symbol. Mars-like worlds which lack any native life (presumably) but are terraformable might be the optimal target for human colonization.


  1. microraptor says

    Next you’ll tell me that despite decades of interspecies relationships in sci fi, having sex with ET would also be a bad idea.

  2. octopod says

    Depends what you mean by sex, I guess. I definitely wouldn’t recommend anything that involves swapping fluids though.

  3. consciousness razor says

    I also suggest that one hypothesis to explain the so-called Fermi Paradox is that habitable worlds evolve such different detailed chemistries that they are basically tainted toxic soups to other species, and that any sensible starfaring species would flag stellar systems with living biospheres with a great big biohazard symbol.

    So when they come to visit, they put on their biohazard suits first. Or they could simply hang out wherever they want in our solar system for an indefinite period of time, studying us or whatever it is they do. Unlike sci-fi books/movies, they may exercise a sensible degree of caution, which is not to say they’ll remain completely undetectable. It would take a while for them to travel here, so they may not feel a need to do stupid stuff which will conclude the plot in the next two hours. But that leaves plenty of other options on the table. One premise we started with is that these things have had an enormous amount of time to work themselves out, yet no evidence we’re aware of has collected in all that time.
    Or, it may be the aliens don’t visit this system at all, but what reaches us here is a signal that they’ve created – one that we could simply detect, whether or not it’s directed at us.
    What you’d have to explain is why we don’t have any evidence like this, even though the probability they exist is supposed to be very high, not just that we don’t have evidence of making tasty recipes out of each other. Maybe we should just conclude that these probability estimates are crap, at least in terms of conforming to our evidence.

    Mars-like worlds which lack any native life (presumably) but are terraformable might be the optimal target for human colonization.

    Okay, but we also don’t have evidence of them trying to colonize Mars, as well as other nearby celestial objects. Maybe they would interested in mining our moons, comets, asteroids and such…. But no. Our neighborhood seems to be a pretty empty place.

  4. springa73 says

    If the chemistry is really different, would it necessarily be toxic, or might it just be something that our bodies couldn’t digest and use for nutrition? In either case, eating it without lots of testing would probably be a bad idea.

    As for the “Fermi Paradox”, I think it’s mainly a problem if you think of extraterrestrial life in the sense of popular science fiction where there are numerous intelligent spacefaring species at the same time in every Galaxy, all at fairly similar levels of technology. If that was the case, it would indeed be strange that we’ve detected no signs. The universe is so vast, though, that it could include trillions of intelligent species while still having an average of only one intelligent species per Galaxy. If that was the case, there’s a good chance that no two intelligent species would ever find each other or be able to communicate. Intelligent life could be common on the scale of the universe but still so rare that each intelligent species is effectively alone.

  5. slithey tove (twas brillig (stevem)) says

    let me strongly recommend her book The City in the Middle of the Night. I’m halfway through and it is an impressive case of world building [a key part of sf story development she often wrote about on io9]. The lead characters share their emotions well.
    Thank you CJA
    Yes i am a fan of CJA from her first SF novel which combined magic and SF into a coherent story.
    No I am not paid by CJA to promote her (hint, I’ll willing accept gratuities, hint hint :-) )
    Thank you for letting me fanrave about CJA

  6. cartomancer says

    The billionaires, on the other hand, pose no such problems. We can eat as many of them as we need to!

  7. John Morales says

    Just watched it. Most excellent; IMO, PZ at his best.

    Hit the spot.

    Nice to follow the biochemical issues, the brief interruption for a “squick factor” appeal, the elaboration of associated issues, and in particular the very final philosophical point (his 3rd appeal to evolution, to be specific).

    In passing, PZ has a nice slow cadence that invites watching at at least 1.25x — so it was not really that long. ;)

    Super-minor quibbles about terminology; ‘culinary’ refers to cooking, it should have been ‘gastronomic’; also, when talking about toxins speaking about eating venom (though I know PZ knows more about that stuff than I do, duh).

    (Actually, the entirety of my quibbles — it was that good)

  8. microraptor says

    octopod @3: What are the odds that ET even reproduces with internal fertilization?

  9. octopod says

    @microraptor: It’s always funny when sci-fi stories assume compatible reproductive anatomy across different life forms, but I guess you gotta keep the monsterfucker contingent happy. That said, it does seem like internal fertilization is surprisingly common among Earth animals. If you want to stay out of the water and keep your gametes from desiccating, it’s pretty much that or super tough spore/pollen coats, really. (Maybe stay off of E.T.’s planet during sporulation season lest you end up with Space Hayfever.)

  10. unclefrogy says

    taking in the vast distances and untile we can go faster than lightt ala the convention of some kind of warp drive which as yet is not even a speculation but a mere fantasy
    the only way we would be able to get some where would be with generation ships. that would be really just man made space colony that can travel across the vast distances and utilizing what ever resources we would find along the way top expand and replicate itself. doubt a destination would even be required.
    I must admit because of my lack of all but a superficial understanding of the biochemistry involved I had no idea what the difficulties could be. Now I understand just how absurd much of the fictional alien interaction really is though as story still engages me.
    thanks for the insight.
    It is becoming clear that there is nothing here on this planet we live on that is not present in simpler forms and without the gravity problem to deal with all over the place in space add to that the biological danger posed by the “biological infestation” it is sounding like the only way we will ever contact anyone else is remotly through text, sound and images using some form of radio or lasers
    uncle frogy

  11. Crudely Wrott says

    P.Z., it appears that you are suggesting that “To Serve Man” is not a cookbook.
    Geeze. Way to spoil a good story.

  12. Gregory Greenwood says

    On the upside. that probably also means that aliens shouldn’t eat us. I choose to look at this as a glass half full type situation.

  13. says

    They’d just drop a rock on us from Saturn’s orbit – humans don’t seem like a particularly smart or worthwhile species. And, if we did meet ET they’d be the starfarers; you do not want to mess with any lifeform capable of interstellat travel.

  14. Stephen G LYNN says

    I think a good place to look is right next door — Venus. There’s been speculation about acid-loving bacteria in its upper atmosphere. Also, (according to Wikipedia), there’s a persistence of three compounds in the atmosphere that normally wipe one another out — hydrogen sulfide, sulfur dioxide, and carbonyl sulfide, so some complex process must be continually producing them (like oxygen on earth).

  15. prez says

    I’m with Crudely. There goes one of my all time favorites. So what shall we serve our alien guests?

    However I recall that most sci-fi movies in the golden (?) age of the ’50’s were far more interested in sex, demonstrated in the subtly named, “Mars Wants Our Wimmin”. Add to that the fact that alien women were all scantily clad hussies and we’re showing our Freudian slips.

  16. madtom1999 says

    The trouble with the Fermi Paradox is it was conceived before the big bang which explains it pretty much fully:
    In order for their to be life you need to be in quiet unfashionable corner of a quiet galaxy on a planet round a 3rd generation star. That’s going to take you 9 billion years before you can start life – any sooner and the local area will probably be too full of radiation that will kill off any attempts at life. Then you have to wait another 4 billion years for it to get to our level of stupid and start looking around for life on other worlds. I think its safe to say there is other life in the universe however we are going to be pretty much in the first vanguard of intelligent life purely because physics doesnt really allow it to start earlier and survive long enough to get intelligent.

  17. jackal says

    The biochemistry was really well explained. You could have skipped the “ick factor” arguments. Those rely too heavily on presupposing your own cultural norms on the future humans who encounter the aliens. There are plenty of present day humans who eat bugs, jellyfish, and octopuses, and have no problem with seeing their food slaughtered or doing it themselves. The moral argument is also moot because all of the sci-fi examples are of people thinking their eating non-sentient organisms only later to find out they were sentient. It’s really the biochemistry that would stop us from eating alien life forms, sentient or not.

  18. kevinv says

    You might want to look for a TelePrompter type app so you don’t have to look down at your notes then back at the camera. I think they’re some good iOS or Android ones you can run on a phone or tablet positioned by the camera.

  19. aziraphale says

    madtom1999 @19: the Fermi paradox was stated in 1950, Big Bang cosmology was conceived in 1931 and had been amply confirmed by red-shift observations before 1950.

    I also don’t know where you get your 9 billion years before you can start life. I don’t see why a Sun-like star that formed 1 billion years before ours would be in a significantly worse environment. 1 billion years head start is plenty of time for the aliens to colonize the galaxy if they have a mind to.

  20. anxionnat says

    Loved the video. Your going on and on reminds me of myself. My mom tells me that I started to talk at 18 months and haven’t shut up since. Maybe those grandkids will do that, too!

  21. birgerjohansson says

    Re.Fermi Paradox. David Waltham in Britain wrote a quite interesting book (sorry forgot title) following up on “Rare Earth” by Brownlee et al.
    He identified many more elements that need to be just right to provide a stable biosphere that will permit complex life to thrive.

  22. Callinectes says

    I loved the video. One other solution to the Fermi Paradox (though it has its problems) is the Dark Forest Hypothesis, which describes a galaxy teaming with life, but who deliberately stay as quiet as possible so not to attract attention from any known or unknown predatory force that might wipe them out.

    Several of the problems you listed were featured in the video game series Mass Effect. Two of the sapient species in the galaxy, the Turians and the Quarians, have proteins of dextro-amino acids. The consequences of eating the wrong food were described as ranging from no effect (though no nutrition) through diarrhoea and vomiting to severe allergic reactions at worst. It makes catering for mixed species a bit of a nightmare (“you don’t mix your spice chirality. What culinary school did you say you went to again?”), though since Krogan drinks routinely set off radiation alarms and hit the human digestive system “like ground glass,” chirality seems to be only one of a plethora of issues for interspecies kitchens.

    Your Captain Kirk-like character gets the opportunity to hook up with certain crew members during the series, several of them alien, and in one memorable scene the ship’s doctor awkwardly advises you not to “ingest” any tissues from the dextro-partners for fear of possible mood-killing reactions, and the Quarian is from a species suffering from extreme immune system deficiencies which puts her at extreme risk of exposure when she permits her suit to be breached in an unsterilised environment (not to mention in an unhygienic way). The toxic skin secretions of a different species apparently causes psychedelic reactions in humans, and the good doctor sees fit to warn you about that also. Or possibly as a recommendation.

    There’s also an amusing tale relayed by a centuries-old bartender about a Krogan who drank a liquidised Turian. “Nobody came out of that one looking pretty.”

    The first game features a world you can visit that has an idyllic habitable band at certain altitudes that are very similar to Earth and would make an ideal colony site, except for the pollen in the air that induces extreme and fatal reactions in any offworlder that breathes it.

  23. microraptor says

    prez @18: A lot of aliens in the 50s were stand-ins for Communists, too.

  24. steve1 says

    Good thing we are getting Space Force. We need them to fight toxic aliens
    and Space ISIS..

  25. pavium says

    In spite of the wishful thinking of SF fans, faster than light travel is fiction and will probably remain so. There is effectively ZERO chance of meeting an alien, and the question is moot, as PZ said.

  26. Crudely Wrott says

    @ pavium, #29:
    I’m not informed enough, nor do I think many others are, to decide what chances there are that we will meet aliens. I do, however, acknowledge your take on FTL travel.
    As far as we can tell, and we can tell very far, to exceed the speed of light would require an infinite amount of energy. That amount is simply not available. One would have to convert every single atom in the universe to move that fast and, all hail mathermatics, the distance traveled would be moot because, should all the atoms be converted to some imaginary fuel and burned with 100% efficiency, there would no longer be any place to go. This is what happens when you attain all the energy in the universe. It is demonstrably better to just take it slow, mosey casually through local space and be on the look out for bacterial or viral life forms and call it a good job.
    That’s probably the best outcome in the foreseeable future. At least until we go all Trump and figure out how to turn all the atoms in alternate universes into energy and go on a witch hunt. At that point our home planet will no longer exist and most of the survivors, not counting those on the B-Ark, will be listlessly coasting towards yet another star with most of its planets in absurdly close orbits around their parent stars.
    Other than that, maybe we should be considering how to go about the business of being the first intelligent specie in the whole of creation. After all, someday we may be faced with actually having to introduce ourselves.
    Oh, my lands and stars (thank you Lila Johnson).

  27. madtom1999 says

    #22 In order for radiation levels to be low near a sun like star it needs to be in a relatively inactive part of a galaxy. This extrapolates to a slow star creation cycle hence the 9 billion years. If you try and do the statistics the chances of a sun like star and low enough radiation earlier than that are astronomically small! Many of the supernovae we see in distant galaxies will wipe out all life in that galaxy. We’ve been incredibly lucky to survive long enough to work out how lucky we are. Even Hart (1975 analysis) doesnt seem to acknowledge the universe as we now see it.
    As for the big bang while it was posited earlier it wasn’t really until 64 when CRB was found that it really started to gain traction.

  28. microraptor says

    madtom1999 @31:

    Many of the supernovae we see in distant galaxies will wipe out all life in that galaxy.

    Citation needed. That seems several orders of magnitude more energetic an explosion than is possible.

  29. says

    I think one of the problems with the Fermi Paradox is that it ignores the question of culture. Fermi assumed that if a civilisation exists that could produce self replicating probes they would do so. Certainly humanity would do so, but there’s no way of knowing if an alien culture would do so. They might think such an effort was a waste of time, or dangerous, or violates the tenants of their primary religion. Or are too busy watching The Real Houseblemnis of Asteroid 36 to bother with interstellar exploration any more.

  30. Gregory Greenwood says

    timgueguen @ 33;

    Or, if you want to go all sci fi horror about it, we might one of the few species foolish enough to scream our existence out into a vast and largely unknown void, totally oblivious as to what might be listening. Other surviving species might either be too prudent to do that, or alternatively have been around long enough to know to a certainty how bad an idea it is to announce your existence to whatever is out there. Other shouty or exploration obsessed species like humanity don’t tend to last long, because if they don’t kill themselves off then something else out there does it for them. We are still about because we live out in the galactic sticks and nothing dangerous has yet heard us, but who is too say how long that state of affairs might hold…?

    Que Twilight Zone/The Outer Limits theme music

  31. pacal says

    Regarding H.G. Wells’ War of the Worlds. Well’s did in fact deal with in his novel with the Martian’s bringing their own life to Earth in his novel. For example he talks about a “plant” called the Red Weed that due to the abundance of water on Earth grows abundantly on Earth before Earth microbes kill it off. Further Well’s fictional narrator concludes that the Martian’s had it seems whipped out most microbial life on Mars uncounted eons ago. Further he contends that the Martian’s seemed to have little to no knowledge of the processes of bacterial decay of dead organisms. In other words the Martians had few, if any microbes to bring with them.