Upon our ambassador’s return from his visit
to Leechian homeworld, he described them as the most noble and wise species he’d ever
encountered, and with a glint in his eye, encouraged all his fellow high ranking leaders
to visit their world to gain a new perspective and enjoy a complimentary stay at the Saunas
of Enlightenment & Implantation. So we return to the alien civilization series
for a look at parasitic & symbiotic aliens. Bit of tricky topic because ‘parasite’
is a somewhat vague word as is symbiotic. The specific biological term isn’t super-precise
either, but it certainly doesn’t mean quite the same thing as we did when we came up with
the word. Originally it meant ‘someone who eats at
the table of another’, and in that context it’s really about the same as saying ‘moocher’,
a bit of slang that was more popular when I was young for a person who lives off others
without giving anything in return. This again can be a bit vague, since one could
argue any hunter or predator was a parasite on whatever species they hunted, as opposed
to a farmer or herder who is arguably in a more symbiotic relationship, you eventually
eat your flock or crop, but provide food and protection in the meantime. So like a lot of terms we look at in science
fiction, we want to be careful about over-extending the definition, for the same reason we wouldn’t
count a person as a cyborg because they had a pacemaker or metal filling in a tooth. The strict biological definition is an organism
that lives on or in another organism, the host, causes it some harm by doing so, and
is adapted structurally to this existence. Which is to say, it’s body has evolved heavily
to fit this role, often to the point that it wouldn’t be functional without it. When we think of parasitic aliens though,
we tend to think of critters that control other people’s minds or eat and replace
us. Brain bugs who land here and wiggle into your
ear, or catch you by yourself and eat you and mimic you to others. There are countless films, books, and TV shows
that have used this, such as John Carpenter’s 1982 Film “The Thing”, which is merely
the third of four adaptation of the novella “Who Goes There?”, by John W. Campbell,
the legendary editor of Astounding Science Fiction Magazine, where so many of the authors
of the Golden age of Science Fiction got their start. You can pick up a free copy of “Who Goes
There?” and also get a 30-day trial of Audible, just use my link, Audible.com/Isaac or text
Isaac to 500-500. So we have a lot of examples from science
fiction to look at and we’ll get through a number of them today, but it’s also worth
noting that we have a lot of surprising examples from nature too. Some are simply outright gross and entirely
harmful to their host, while others actually provide some benefits, and are arguably symbiotic. But we tend to assume that critters like this
couldn’t really evolve a civilization because they’re not really smart themselves. Indeed many of our examples for today from
fiction could only be considered ludicrous from an evolutionary perspective, and for
many others, their parasitic nature is more behavioral, they only latch on to us and feed
in a metaphorical sense. It’s worth mentioning though that quite
a few parasites do engage in mind control or impersonation. For mind control, we have any number of fairly
revolting parasites that either directly infect the brain or perhaps the spine or sometimes
even just the digestive system and create cravings for a food their host normally would
not have. An alien parasite, for instance, might get
in someone’s stomach and cause them to have a craving for minerals heavy in Tungsten,
because it needs Tungsten to live. Many of these are nearly brainless, even compared
to their often rather stupid hosts, yet can annex their motor functions and control them. We’ve got a type of fly that infects ants
with eggs, which when the larva hatch crawl into its brain, eats it, and causes it to
continue to act and work like normal till it has a chance to bury itself somewhere so
the fly can finish maturing. This can happen with no brain at all either. We’ve got a fungus that infects caterpillars
and actually causes them to plant themselves by burying their head upside down in the ground,
and then uses them for nutrients and as a stalk it sprouts from. This can also sometimes be a bit symbiotic,
we’ve got a type of acacia tree that ants love the nectar from, so much so they’ll
protect that tree from animals and weeds, which sounds mutually beneficial except the
ants not only get addicted to that nectar, but lose the ability to digest anything else. Still these are all fairly simple organisms,
indeed those last two were mindless, but for parasitic behavior by impersonation we’ve
got some clever ones. Perhaps the best known example is the brown
headed cowbird, that lays its eggs in other birds’ nest, often after destroying the
eggs already there, and is called a brood parasite, as it relies on other animals to
actually raise its young. There are many species that do this, but the
cuckoo stands out as birds are generally considered the smartest class of animals after mammals,
and indeed a few are smarter than many mammals, which would indicate this is a plausible evolutionary
pathway for a species to take on the road to higher intelligence. A parallel to brood parasites are social parasites,
like certain types of bees that invade a hive, replace the queen, and let the workers continue
to feed them and care for their own young, that’s a strategy that’s often implied
in a lot of secret alien invasion scenarios where, for instance, an alien might impersonate
a leader. We’ve also got Kleptoparasites, that steal
food gathered by the host, and that’s got some interesting extreme variations like the
tongue eating louse, which infects fish, cuts off their tongue and latches onto the stump
to replace it. Regular viewers will note that, unlike in
many episodes, I did not suggest getting a drink and snack before beginning, as many
of these little monsters are rather unpleasant to look at or contemplate. However, there is the symbiosis route, and
for instance a species might replace something’s tongue with itself, and steal some food that
way, but give a heightened sense of taste or smell in exchange. Humans have a huge number of somewhat symbiotic
bacteria inside us, ranging from our gut bacteria that helps us digest food to mitochondria,
the separate bacteria-like powerhouses that live in the thousands in each of our cells
and make up one fifth of our typical cell by volume. Nor does our intelligence keep us from being
mind controlled by something much stupider. The Influenza virus is often considered parasitic,
indeed it’s sometimes called the perfect parasite, in that it’s thought to make people
infected with it act more social, thus being around more people and infecting more of them. Any parasite that relies on its hosts interacting
with each other to spread benefits from a more social species, so for instance one that
could cause you to feel drunk might be very effective. Keep that one in mind for later, as we’ll
discuss how alien beer may represent one of the more likely scenarios for being destroyed
by aliens, and yes I did say alien beer. It still seems very unlikely something could
evolve to higher intelligence by being a parasite, let alone one able to parasite critters with
an alien biology. However here’s three caveats on that, first,
that impersonation pathway the cuckoo uses benefits from higher intelligence, and mimicking
a critter doesn’t necessarily require compatible biochemistry. One could imagine something taking a chameleon
pathway. Second, a species that evolved with technology
might no longer act in ways their ancestors did, like I don’t tend to go swinging around
trees or even chasing mammoths, but it probably shapes their philosophical outlook and how
you’d interact with them. They might be very predatory or parasitic
even if they weren’t openly hostile. Pierson’s Puppeteers from Larry Niven’s
Ringworld and Known Space series are a good example of that, especially as we get to know
them. They are initially described as tri-sexual,
with two genders that are smart and a third described as non-sentient. We later find out that it’s not really a
third gender at all, one fertilizes another, as normal, who then lays an egg in some unrelated
creature with an ovipositor, like a wasp. This is also our third caveat, because while
here we see they’ve developed a close enough relationship with that species they lay their
eggs in to regard them as part of their race, it’s not hard to imagine more symbiotic
versions of this. Interestingly, while we don’t hear much
about that egg-bearing host species, odds are the Puppeteers see to their needs the
same as a farmer to his livestock. This isn’t a loving and warm relationship
but is arguably mutually beneficial. You also can have back and forth evolution
where parasite and host, or symbiote and host, push each other to evolve. This is presumably the case for one of science
fiction’s best known symbiotic races, the Trill from Star Trek. That’s a weird evolutionary path, basically
a big swimming brain, very akin to to Gou’ald from the Stargate Franchise, or their nicer
cousins, the symbiotic To’kra. But let’s imagine an advanced form of that
fly from earlier that gets into ant brains, eats the brain, and replicates their behavior. We often say a good parasite is one that never
actually kills the host, and of course symbiosis relies on this too. So imagine it didn’t quite eat the brain
but hijacked part of the brain and the nutrient system feeding it, grows on the ant’s back
like a big hump, spawns, and flies off and lays another egg in another ant. Over time, this could setup a symbiotic relationship
with feedback encouraging more intelligence in both parties, and potentially the sharing
of sensory functions, if the parasite had a better set of eyes, for instance, to spot
its host. This could get very integrated with time and
increasingly complex, and potentially even end with the host intentionally and knowingly
transferring mature parasites from other hosts and sticking them on their kids. Indeed, being able to put a smarter, older,
wiser parasite on your kid to act as a babysitter and teacher would have some major survival
advantages. With this system in place, that parasite no
longer benefits from having any motor system itself, even to jump onto its host, and actually
gains from being smarter and wiser and longer lived, since those would be the preferred
babysitters. So you could end up with something that was
a parasite originally and now was essentially nothing but a symbiotic brain. One can imagine them eventually become a high-tech
democracy that always elected the brain slugs since everyone was so used to them as a wise
parental authority figure. It wouldn’t be very likely it could infect
any other species, let alone an alien one, but there’s some ways around that too. First, for other species of the same planet,
we often talk in sci-fi about colony organisms or brains that are essentially networks of
fungus or algae, such as the Pattern Jugglers in the Alastair Reynold’s Revelation Space
series or the Xeno Fungus from Sid Meier’s Alpha Centuari. One can imagine those as your early brains
and hijacking every animal nearby, like that fungus we mentioned that hijacked caterpillars. And we certainly have plenty of examples of
plants that already somewhat hijack many species for their survival and reproduction, relying
on them for pollination or eating fruit to be carried away and planted. So you might have some algae intelligence
in a pond that had hijacked every fish and frog and insect to do its bidding, in which
case, increased intelligence is handy since it lets you better control your minions in
what is now essentially a hive mind. It also has every motivation to kill off any
species it can’t control. As to non-hive mind alien parasites, that’s
harder of course. Fiction has plenty of examples, the Xenomorphs
from the Alien Franchise, who lay eggs in you that kill you when they hatch, again like
a wasp. We also have the Tyranids from Warhammer 40k,
a setting with plenty of parasites including the Emperor of Mankind, who eats a thousand
people every day, though this is arguably symbiotic. The Tyranids are definitely not symbiotic,
but are a bit more subtle than the Xenomorphs sometimes by infecting people with what they
call Genestealer Cults, hybrids initially raised by infected parents whose brains have
been ravaged so they can’t even realize their cute new bundle of joy is a monster,
an example of a brood parasite like the cowbird. Of course, later the Tyranids just turn everything
biological on the planet to soup, and reconstitute it into more versions of themselves, slightly
evolved from their original form - a more believable way to parasitize a whole planet. However while they make good fiction, it’s
hard to imagine how something from another planet could evolve to take over your brain. So much like vampires, another parasite of
fiction, they make good stories but wouldn’t seem too plausible. But if you’re on alien planets, it usually
implies you have space travel which implies you have technology. You could engineer yourself to incorporate
biological enhancements, possibly to adapt to a new environment, or even go post-biological. The Borg from Star Trek would be an example,
who act exactly like our algae intelligence of a moment ago, they steal bodies to act
as minions basically. This is actually an example that could be
a credible threat to us, given how divergent we expect to be from aliens biologically. As a cyborg, though, you wouldn’t really
need to interact with the diverse nervous systems or biologies of your hosts. You could, in theory, simply locate the motor
neurons for the host and puppet their bodies using electrical impulses, in much the same
way as the Gou’ald did but not in a biological way. The host could still be aware and living on
in their own brains but unable to interact with the outside world. There are plenty of other examples too, The
Vex from the video game Destiny, arguably even the Reapers from the Mass Effect Franchise,
especially as allegedly in the original plot they were indeed farming and reaping civilizations
to borrow their intelligence or perspective to solve a problem. The Borg also steal knowledge, assimilating
cultures and technology, and that’s an example of where you might see parasitic tendencies
in a non-hostile body-stealing way. Aliens who love knowledge or poetry or art
and visit planets with emerging civilizations just to get theirs, either by open trade or
exploitation or outright invasion. As we said the term itself originally meant
‘someone who eats at the table of another’, a mooch, and the most effective folks at that
sort of behavior are the ones who make themselves welcome. It’s a bit of a gray line, I guess the analogy
would be that a travelling storyteller who visited farmhouses and told stories in exchange
for a bed and meal, a symbiotic behavior, versus one who did that, but burgled their
cellar before leaving, but did so in just small enough quantity and covertly so that
they didn’t notice and cheerfully bade him a good trip and welcomed him back when he
next returned. And again, same as a parasite might evolve
to be fairly noble, a non-parasite can certainly exhibit parasitic behaviors, like that storytelIer. The Stargate Franchise gives us the Gou’ald
as an example of parasitic behavior and the To’kra as symbiotic ones, but it also shows
us the vampiric Wraith and even the Aschen, a society that essentially showed up on other
planets and offered lots of technology, including life extension, Technological Uplifting, but
then would wipe out most of the local population through a sterility plague and in one case
reduced the natives to fairly simple and backwater farmers who supplied food to their empire,
unaware they’d been victims of that empire. Indeed you might subtly invade a planet in
stages that way by offering them a genetically modified crop that was much more productive,
that you could also eat, and whose pollen rendered people stupider or less fertile. This is a common theme in fiction too, aliens
openly greet us, rather than sneaking in, offer us technology, but have an ulterior
motive. The Taelons from Gene Roddenberry’s Earth
Final Conflict show up on Earth doing nothing but good deeds but while not implied to be
evil as a species by any means, have a lot of rather dark projects and members. One of which was a symbiote they’d give
people that shot energy blasts and another called a Cyber Viral Implant that enhanced
cognition and recall, but also tampered with your mind to make you loyal to them. So they’re friendly alien visitors with
sinister plots. That can go the other way too. In another TV show, Threshold, there is an
apparently evil invader race taking people’s brains over but it’s hinted near the end
they might be trying to help us out. Sadly we don’t get to find out as it only
got one season, in spite of having Brett “Data” Spiner and Peter “Tyrion” Dinklage in
it. But while we can point out the options technology
offers to let you get around the alien issue, we also shouldn’t discount that something
might be able to get us as a parasite even if it wasn’t technological. You don’t necessarily need the same biochemistry
or adaptation to a specific host organism to puppet or impersonate someone. While life probably originated on Earth in
deep sea vents or tidal pools, we can’t rule out Panspermia, life distributed around
the cosmos by comets or interstellar dust, permitting a common basic biochemistry. Moreover, while we can’t rule out alternate
chemistries for life, it’s quite possible our carbon and water approach is the only
viable one, and is almost certainly the easiest and most common one, those elements being
way too common in places where there’s plausible conditions for advanced and diverse life. Now we often say here that you wouldn’t
want to ever land on an alien planet, even in a space suit, since just sneezing could
infect a planet to the point of total extinction in favor of what you had in you. However, we’re not really talking about
viruses, the simplest parasite and one usually so adapted and simplified it can’t even
infect a species just a few million years removed from its preferred host. Hence why you don’t often get colds from
your cat or dog, but it can happen. But more importantly, microbes in your body,
not viruses, just need basic nutrients, ones probably present on most life-bearing planets. Giant viruses could theoretically bridge that
gap however. With more than double the amount of genes
of their smaller cousins, they are often mistaken for bacteria. As an example, the Pandoravirus is a huge
virus with over 2000 genes, most of which we haven't found anywhere else on earth. And many viruses have the ability to survive
in the harsh conditions of space, often raining back down on us from above. With more genes and diversity than smaller
viruses, the potential for them to turn symbiotic and/or parasitic is there. And the Pandoravirus isn’t even the largest
or most diverse. The more specialized a cell is, generally
the less adaptable it is in changing conditions. However these large viruses are so diverse,
who knows in what conditions or species they may one day call home? One way that such a virus could infect diverse
hosts is if it is designed to do just that. This ties into alien abductions, where an
alien race arrives at a planet, collects samples from its local flora and fauna and then sets
about designing a doomsday genetic weapon that is capable of wiping out every species
on that planet, or at least the intelligent ones. If you design a big enough genome and have
a powerful enough computer to design such a weapon, I think you could pull that off. This is similar to the Shadows plague virus
in the Babylon 5 universe that decimated Earth and destroyed many other worlds. It was automated in that it had a parasitic
learning phase where it quietly infected its hosts and learned from the physiology of its
victims without actually harming them and then adapted itself before dealing the final
deadly infection phase that quickly wiped its hosts out. The Shadows in the Babylon 5 series also had
a mind-controlling puppeteer called a Drakh Keeper that they modified to the biology of
the host and infected them to do their bidding in a more traditional parasite role. So, you will probably never shake hands with
an alien, since you’ll both be potential walking plague carriers, and their embassy,
if they have one in your system at all, might be on an island but much more likely won’t
even be on the planet, but on a space station. With enough technology in play people could
presumably visit and maybe eat the food, which of course they would if they could. Not only would people want to try exotic alien
cuisine on general principle, but big and expansive empires tend to have the best selection. They are also fairly likely to try the booze
too, which aliens might well have. So diplomats and traders are likely to be
up there in person, and eat and drink the stuff even if it requires decontamination
procedures on your guts by some device of a unsettlingly tentacular nature. When they get home, they are likely to rave
about how excellent it is, probably even if it wasn’t. Of course you can’t let anything with a
live culture down on the planet and you need to be sure all the microbes are gone. You don’t want those microbes down here
and the aliens might well be smart and benevolent folks who don’t want that either. You could, in theory, brew up vats of beer
or yogurt or cheese using alien microbes, and maybe safely by having the place be off-world
or like a biohazard lab, but odds are it would be banned on general principle. Now as everyone knows, the only thing that
makes a cigar or drink better is if it comes from some place under embargo and sanction,
and let’s be honest, if someone offered you a forbidden alien beer, you are going
to have a rough time saying no and aren’t likely to report them. This also means there’s now a black market
for it, only anyone supplying it isn’t likely to be making it in an ultra-safe biohazard
lab but rather brewing it up in their bathtub like moonshine. So next thing you know, you’ve been invaded
by aliens and your ecosystem wrecked, not because they’re parasitic or bad guys, but
because someone couldn’t resist having a drink. And who can blame them, Alien Beer is to die
for. All right, so some food for thought about
alien ecosystems and parasitic aliens. Personally I don’t think we need worry about
it much, even ignoring my usual skepticism about us encountering any aliens civilizations
at all, because I do think brain bugs or mimics able to originate in alien ecosystems but
still get humans is a pretty unlikely evolutionary scenario, biologically or culturally. This is especially true when it comes to the
divergence of biological systems, even here on our own home planet and other planets are
likely to be so much more different from our own. However, it’s not something we can completely
rule out. Regardless, it definitely makes for some good
stories, and one of the best of those is John W. Campbell’s classic novella, “Who goes
There?” which inspired so many more stories. In spite of being a classic that’s been
turned into popular film’s many times, the story varies from them quite a lot and is
not one we can discuss without ruinous spoilers, so I’ll limit myself to saying you’ll
still be surprised even if you’ve seen all the film adaptations, and you will quickly
realize why John W. Campbell is considered one of the grandfathers of science fiction
whose work explores so many fascinating concepts. You can get a free copy of “Who Goes There?”
today, just use my link in this episode’s description, Audible.com/Isaac or text Isaac
to 500-500 to get a free book and 30 day free trial, and that book is yours to keep, whether
you stay on with Audible or not. And while you’re there, you can explore
their catalogue, and find some more books you can listen to and enjoy, while still out
enjoying your summer. So we talked a lot about alien biology and
Earth’s biology, and next week we’ll be taking a deeper look at ecology in space,
as we consider how you would move large and complete colonies on interstellar ships to
colonize other worlds, in “Exporting Earth”. We also talked today about alien invasions,
and we’ll be looking at that and other futuristic warfare scenarios in two weeks, when we examine
the use of drones, remote controlled and autonomous, as weapons in “Attack of the Drones”
For alerts when those and other episodes come out, make sure to subscribe to the channel. And if you enjoyed this episode, hit the like
button and share it with others. Until next time, thanks for watching, and
have a Great Week!
