A man and his botfly
May 1, 2016 2:10 PM   Subscribe

Parasites Are Us: How biological invaders challenge our idea of self and other
The maggot was never invited into Coyne’s head. For those weeks it lived there, however, wasn’t the maggot in many ways literally Coyne? After all, other than the tip of its breathing tube, the maggot existed completely inside his body. Besides, the maggot was flesh-and-blood Coyne in the most literal sense: Almost the entirety of its physical bulk consisted of Coyne’s tissue.

“It was eating my muscles and tissues and scalp,” he said. “It’s turning human flesh into fly flesh.”

“And when I went swimming or took a shower, it would sort of freak out because its airhole would be cut off, then it would really go nuts. You know, make a lot of pain. So I tried to avoid getting my head under water.”

Botflies feed on the mammal’s tissue until, after about six weeks, they’ve grown big enough to survive on their own, and then they exit through the hole in their host’s skin. Coyne happened to be the host this time around.
posted by wonton endangerment (56 comments total) 27 users marked this as a favorite
 
Pre vi ous ly
posted by wonton endangerment at 2:22 PM on May 1, 2016


[more inside] indeed.
posted by now i'm piste at 2:23 PM on May 1, 2016 [45 favorites]


Within a couple of weeks it had become the size of an egg, then a quail egg. Coyne started wearing a baseball cap.

/facepalm
/thinks twice, inspects palm for intruders; we're good
/facepalm again
posted by Cool Papa Bell at 2:23 PM on May 1, 2016 [9 favorites]


Not gonna read, because this stuff sticks with me, but Carl Zimmer is a fantastic popular biology writer with a book titled PARASITE REX: Inside the Bizarre World of Nature's Most Dangerous Creatures. Those who like this sort of thing should like it.
posted by benito.strauss at 2:31 PM on May 1, 2016 [2 favorites]


"At what point do self and non-self merge? What if your own cells were built by an outsider and customized to house that outsider—who would be the tenant and who would be the landlord? Who makes that call? "

How does an entire article about this, including a bunch about immune responses and mitochondrial DNA and the quote about "the maggot existed completely inside his body. Besides, the maggot was flesh-and-blood Coyne in the most literal sense: Almost the entirety of its physical bulk consisted of Coyne’s tissue," NOT make the obvious comparison to gestation, probably the ultimate human "intruder" situation where the interloper "[steals] what it need[s], and, when [the host] was no longer useful, went off to live an independent life."?

Oh, right, dude scientist writing about dude scientist. But SERIOUSLY, it a major oversight, when the whole article is about the same damn processes, and he even goes to mitochondrial DNA as a human example of parasitism, but skips reproduction itself? I guess all these parasitic processes of conflict and resource theft and encapsulation to prevent immune attack and so on aren't interesting when they're happening to women. Even if it's clear that gestation obviously fits his interest: "The fact is that all of the “others”—whether they are parasitic or mutualistic, cheaters or straight-shooters, long-term residents or one-night stands—have a significant characteristic in common: They each carry their own DNA. And this means that, for however long they are inside their host’s body, two genetically distinct organisms are living under the same skin and, to one extent or another, are biologically intertwined." And is obviously the clearest example of the problem of where self and non-self merge.
posted by Eyebrows McGee at 2:31 PM on May 1, 2016 [93 favorites]


Wow, it is really time for me to take a shower.
posted by limeonaire at 2:40 PM on May 1, 2016 [2 favorites]


I don't know why, but I think I'm done getting freaked out when nothing in the world has really changed but somebody has found a new way to describe it that would be disturbing if it actually changed anything--which seems to be a staggeringly huge proportion of what we spend time reading, thinking, and worrying about.
posted by saulgoodman at 2:49 PM on May 1, 2016 [1 favorite]


I know someone who studied bot flies and whether infection interfered with the reproductive success of chipmunks. I am sure she would snort at this.
posted by acrasis at 2:51 PM on May 1, 2016 [1 favorite]


So why is the parasite tongue forever an outsider? Just because it happens to have legs and eyes?

Is this a trick question?
posted by Johnny Wallflower at 3:06 PM on May 1, 2016 [14 favorites]


gestation ... dude scientist writing about dude scientist

See, that's why I like MeFi. I never would've thought of that. Unironically, seriously, /hat tip
posted by Cool Papa Bell at 3:06 PM on May 1, 2016 [23 favorites]


I guess all these parasitic processes of conflict and resource theft and encapsulation to prevent immune attack and so on aren't interesting when they're happening to women.,

Seems like a bit of a generalization based on a single article (which is an excerpt from a book) that launches its thesis from a botfly infection. Unlike CPB, this is precisely what I *don't* like about "MeFi". Tastes differ.
posted by smidgen at 3:13 PM on May 1, 2016 [8 favorites]


Goddamn Neolutionists! :[
posted by sexyrobot at 3:15 PM on May 1, 2016 [6 favorites]


I don't really agree with the "dude scientist" criticism. Comparing pregnancy to a botfly infection seems like its own minefield. I think comparing a pregnant woman to a parasite host and characterizing a fetus as a "biological invader" akin to a botfly maggot might be kind of in poor taste, too.
posted by dialetheia at 3:25 PM on May 1, 2016 [23 favorites]


The idea that nobody at Harvard had heard of botflies is pretty nuts.

I spent a few weeks hiking in Brazil in 2008. What I was told to do in case of botflies: cover the hole on petroleum jelly, wait for the little bastard to suffocate, and pull it's corpse out with tweezers. No scalpel necessary.
posted by evidenceofabsence at 3:35 PM on May 1, 2016


Is it wrong that I imagined this happening to Wayne Coyne
posted by Merzbau at 3:36 PM on May 1, 2016 [16 favorites]


(I'm probably just disappointed because the artice is not about Wayne Coyne.)
posted by evidenceofabsence at 3:36 PM on May 1, 2016 [3 favorites]


To expand on why I don't think reproductive processes are considered here, this whole article is in the context of evolutionary biological research about interspecies interactions - specifically parasitism and mutualism. Reproduction doesn't fit into this framework because it's a relationship between organisms of the same species (not to mention that it concerns organisms that share genetic material, which are usually analyzed in a totally different framework because their relationship is strongly influenced by genetic kinship). The way they bring up mitochondria might seem to blur the lines because they are integrated into our cells, but that was an endosymbiotic association as far as we can tell - those cells were originally an entirely different organism. I agree that reproductive processes can also provide a good lens through which we can analyze self/non-self divisions, but I think in this context, it was pretty clearly about where that line gets drawn with respect to interspecies relations.
posted by dialetheia at 3:52 PM on May 1, 2016 [12 favorites]


I literally do not know a single woman who has been pregnant who has not at some point referred to the fetus as a parasite, with varying levels of seriousness. It can be an experience just as unsettling as playing host to a botfly. I mean, the article is about non-human parasites and that's fine but I wouldn't call the connection to pregnancy in poor taste, if the pregnant ladies I've known (including myself) are anything to go by.
posted by soren_lorensen at 4:01 PM on May 1, 2016 [32 favorites]


I know women who have joked about parasites and invaders, and others who haven't. I don't think it would ever occur to my wife, for example, to make such a comparison. It's as much a derail in a serious discussion about parasites as it is here though.

There's an interesting discussion to be had about the biological space parasites inhabit. They're basically pirates who steal energy or use a host's cellular mechanisms to make their own bodies and offspring. Most are completely dependent on their hosts for the future of the species, and both parasites and hosts have highly evolved strategies for dealing with the other. In some ways, we're the rocky hillside on which various parasites eke out a meagre living. Who'd a' thunk it?

Is this a good place to plug the podcasts at This Week in Parasitism? Because they're pretty great, and they're mostly dry enough that you won't be squicked out. Nobody's saying you have to go look at the pictures.
posted by sneebler at 4:12 PM on May 1, 2016 [3 favorites]


So why is the parasite tongue forever an outsider? Just because it happens to have legs and eyes?

"Paging Dr. Cronenberg. Dr. Cronenberg to the ER."

But seriously, a friend of mine returned to his northern Ontario town after a trip to somewhere bot flies are a possibilty.

When he presented to his local GP with the larva, it was the hit of the local hospital (there are only three or four doctors in this town at any given time, the local clinic is in the hospital, and it's three hours to any large urban centre, so everybody's going to know).

His GP went apeshit on the clinical literature. He recalls that every visit was an exercise in "THIS IS SO COOL! I NEVER SEE THINGS LIKE THIS!"

They let the bot fly do its thing and emerge. He's now the "bot fly guy" when he swings by for a checkup.
posted by mandolin conspiracy at 4:15 PM on May 1, 2016 [18 favorites]


Reproduction doesn't fit into this framework because it's a relationship between organisms of the same species (not to mention that it concerns organisms that share genetic material, which are usually analyzed in a totally different framework because their relationship is strongly influenced by genetic kinship).

Actually, there's a long history of work on the evolutionary relationships between mothers and offspring, especially in mammals where offspring demand a lot of energetic resources from mothers. In fact, even though the interests of mothers and offspring are mostly aligned, they're not perfectly aligned. Each individual child wants to extract as many resources from a mother as it can for its own use, whereas mothers would generally prefer to be able to invest their resources in more than one basket. (Fathers, especially in systems where monogamy isn't the norm and the next kid a given mother has might or might not be his, would generally rather any offspring that get born now take as much as it can and run.) This framework deeply underpins our understanding of things like genetic imprinting, which involve a history of maternally and paternally mediated conflicts about how much energy a given offspring should take to let it grow.

This field usually goes by the term sexual conflict, and while it isn't as simple as parasitism and mutualism seem to be on first blush, it has a lot in common with interspecies relationships and the field has a lot of intellectual crossover. That's especially true, I think, of systems where different species have interests that are sometimes aligned and sometimes conflicting--like hyphae/root mutualisms between plants and fungae, where the two species trade for the types of nutrients that each has an easier time soliciting.

On a more literary note, I'm strongly reminded of Octavia Butler's work, which uses sci-fi to explicitly draw those parallels between parasitism and pregnancy, and also parasitism and mutualism. Where's the line? It's not always as obvious as it seems.
posted by sciatrix at 4:16 PM on May 1, 2016 [50 favorites]


That's super interesting, sciatrix! I still think the piece was pretty obviously centered on interspecific interactions and thus I don't really see it as inappropriate that they neglected reproductive processes, but that's fascinating nonetheless.
posted by dialetheia at 4:24 PM on May 1, 2016 [3 favorites]


Sarah Blaffer Hrdy talks about the placenta and fetus in parasitic terms. Fascinating stuff. Depending on the complications of male parental involvement and maternal care after birth, it may be in the interest of the father's genes to suck as much life out of the mother as possible without killing her. (That obviously won't be the case for, from earlier today, white-spotted pufferfish.)

[On preview, what sciatrix said.]

But none of that prepared me for this:
"The botfly wasn’t that painful and I knew it was going to come out on its own after a while,” Coyne told me. He decided to just try to enjoy and marvel at what was happening inside him as much as he could.
[shudder]

That's one way for mutually beneficial inter-species symbiosis to get started, I guess.

FWIW, Jerry Coyne is all about the idea of the fetus as a parasite. He even uses the idea in a pro-choice argument.
posted by clawsoon at 4:29 PM on May 1, 2016 [2 favorites]


Yeah, having actually read the piece now (yes, I was that person).... I'm even more irritated that pregnancy doesn't get mentioned, because to me the piece is explicitly centered on the question of what defines selfhood within a body that is composed of cells that come from multiple individuals. And motherhood and gestation are both incredibly salient topics that need to come up in a discussion of that question. Hugely so, in fact; the only other situations within a species that I can think of that are so central to that question aren't particularly relevant to humans.

For example, look at the placenta--its entire function is centered around fusing itself to maternal organs and maternal blood supply, and it quite literally invades a mother's blood vessels in order to grab oxygen and sugars from her bloodstream. It's made up of fetal tissue. What's more, that fetal tissue establishes itself in a mother's body and can be found long after the offspring has been born. Those fetal cells interact with a mother's body and communicate with it, sometimes apparently in mutualistic ways and sometimes in ways that are rather more reminiscent of the ways that some parasites can control the behavior of their hosts.

I mean, he's explicitly getting into mosaicism; why not mention the most common form of human mosaicism? Grump, grump. He could have gotten into so many more directly relevant examples to humans that we know about! The article is so very human-focused, after all, except for that little discussion of the crustacean that becomes a fish tongue; why not tie the piece together with a more concrete example of a tissue invasion that sets up shop and vacillates between different kinds of interactions? I'm kind of astonished he didn't mention anything to do with pregnancy at all!
posted by sciatrix at 4:41 PM on May 1, 2016 [39 favorites]


oh god like i needed another reason to hate mosquitoes
posted by allthinky at 4:43 PM on May 1, 2016 [1 favorite]


Penny Arcade: The Bump
posted by Sebmojo at 4:58 PM on May 1, 2016 [3 favorites]


From the lowliest human fetus to the majestic botfly larva, we are all starstuff.
posted by Existential Dread at 5:04 PM on May 1, 2016 [9 favorites]


But parasites aren't defined in relation to individual selfhood but on the basis of species level identity. Personal identity isn't all we have now, is it? That'd be a pretty paltry, lonely thing to have, each one of us the last scions of a very lonely, dying race...
posted by saulgoodman at 5:25 PM on May 1, 2016 [1 favorite]


saulgoodman: Deep-sea anglerfish males are often called "sexual parasites", since they meld themselves into the female's body and receive all their nutrition from her. Presumably it's a net win for the female; the theory I've heard is that finding a mate in the deep sea is so difficult that she doesn't mind him hitching a ride for the rest of his life.

So is he a parasite, or is it just an amusing counter-intuitive way to think about the interactions of life?

That'd be a pretty paltry, lonely thing to have, each one of us the last scions of a very lonely, dying race...

It only has to feel lonely if that's what you're feeling already. If you think about the fact that most of the cells in your body aren't even you, you could celebrate it all as a parasite party. Sometimes the line between parasite and symbiont isn't at all clear, so you might as well enjoy that we're all in this together. No matter what, RNA and DNA polymerases will use us all, all the varied expressions of life, to keep themselves going for another few billion years - one way or another.
posted by clawsoon at 6:04 PM on May 1, 2016 [5 favorites]


How does an entire article about this, including a bunch about immune responses and mitochondrial DNA and the quote about "the maggot existed completely inside his body. Besides, the maggot was flesh-and-blood Coyne in the most literal sense: Almost the entirety of its physical bulk consisted of Coyne’s tissue," NOT make the obvious comparison to gestation, probably the ultimate human "intruder" situation where the interloper "[steals] what it need[s], and, when [the host] was no longer useful, went off to live an independent life."?

Oh, right, dude scientist writing about dude scientist. But SERIOUSLY, it a major oversight, when the whole article is about the same damn processes, and he even goes to mitochondrial DNA as a human example of parasitism, but skips reproduction itself? I guess all these parasitic processes of conflict and resource theft and encapsulation to prevent immune attack and so on aren't interesting when they're happening to women. Even if it's clear that gestation obviously fits his interest: "The fact is that all of the “others”—whether they are parasitic or mutualistic, cheaters or straight-shooters, long-term residents or one-night stands—have a significant characteristic in common: They each carry their own DNA. And this means that, for however long they are inside their host’s body, two genetically distinct organisms are living under the same skin and, to one extent or another, are biologically intertwined." And is obviously the clearest example of the problem of where self and non-self merge.


Actually the article would have been much, much stronger and better focussed if it had started with pregnancy and used that as the ruling metaphor for parasitism, because the way we and other mammals do reproduction requires the existence of a hole in our immune defenses that the fetus can fit into, and though I'm not sure how much work has been done to explore ways in which parasites have exploited that hole, I think it's a virtual certainty that many have and do, and it's beginning to be almost received wisdom that mammals are much more vulnerable to cancer because we have to have immune systems which can accommodate the fetus.
posted by jamjam at 6:20 PM on May 1, 2016 [15 favorites]


To rerail slightly (depending on one's view of viruses as parasites), there's been some research that the ability of the placenta to attach and survive is due to (apparent) viral genes.
posted by MikeKD at 6:34 PM on May 1, 2016 [6 favorites]


This might be were I ran across the info
posted by MikeKD at 6:35 PM on May 1, 2016 [1 favorite]


I strongly recommend everyone run a Google image search for human botfly
posted by beerperson at 7:31 PM on May 1, 2016 [6 favorites]


cover the hole on petroleum jelly, wait for the little bastard to suffocate, and pull it's corpse out with tweezers
I also read about the "meat cure", either in an Oliver Sacks book, or perhaps a David Quammen book, I can't quite remember where. The idea is you put a piece of raw meat over the hole, and the botfly larva burrows into the raw meat, not realizing its exiting its host. Then you pull off the meat with the botfly larva inside.
posted by smcameron at 7:45 PM on May 1, 2016 [1 favorite]


Oh here's a youtube video of botfly larva removal, but not using the meat cure method.
posted by smcameron at 7:48 PM on May 1, 2016 [1 favorite]


That's a great comment you linked to, MikeKD.
It should be noted that an Amoeba, which is a solitary cell, would have much the same trouble contemplating the individuality of a human. Humans function as ecological, behavioral, and evolutionary individuals. But they are made up of many cells. So is the entire human an individual, or are each of the cells individuals?
That gets me thinking about cancer as a parasite. A descendant of one of our cells becomes different enough from the rest of us that it forms what is, in some ways, a new individual. If it's benign, it becomes a parasite that's along for the ride, sucking up resources without killing us. If it's malignant, it's a destructive (and self-destructive) parasite that eats its host from the inside out, ultimately killing itself, too. If it's exceptional, it becomes the HeLa cell line from Henrietta Lacks or the devil facial tumour disease, a sort of species in its own right.
posted by clawsoon at 7:55 PM on May 1, 2016 [2 favorites]


If you think about the fact that most of the cells in your body aren't even you, you could celebrate it all as a parasite party.

Actually, this topic is now being disputed (Nature).
A 'reference man' (one who is 70 kilograms, 20–30 years old and 1.7 metres tall) contains on average about 30 trillion human cells and 39 trillion bacteria, say Ron Milo and Ron Sender at the Weizmann Institute of Science in Rehovot, Israel, and Shai Fuchs at the Hospital for Sick Children in Toronto, Canada.
I've always found the presentation of this concept frustrating, because even if you accept the 10:1 ratio of microbial cells to human cells, by mass and by function you are overwhelmingly human.
posted by Existential Dread at 8:03 PM on May 1, 2016 [4 favorites]


I mean, he's explicitly getting into mosaicism; why not mention the most common form of human mosaicism?

Unsurprisingly, when I looked up the book this article is an excerpt from -- it actually did go into that.
posted by smidgen at 8:18 PM on May 1, 2016 [5 favorites]


If you think about the fact that most of the cells in your body aren't even you

Or you can look at the same issue from the flip side, and conclude that descent from an egg cell and sperm cell belonging to your parents is not a necessary criterion for defining a cell as "yours".

Many of my microbial cells are, I am sure, also descended from those of my parents.
posted by flabdablet at 8:35 PM on May 1, 2016 [5 favorites]


brundefly to the white courtesy phone
posted by davidmsc at 9:42 PM on May 1, 2016


Many of my microbial cells are, I am sure, also descended from those of my parents.

My understanding is that it's not actually clear what proportion of microbes are coming from the environment and happening to colonize multiple people who are cohabitating and eating similarly (e.g. mom and kid), vs. what proportion are actually directly transferred from mom to kid at some point in the kid's development. Really hard to tease those things apart! Gut microbiomes in particular can be pretty dynamic and respond to long-term and short-term diet, and the infant gut microbiome actually looks totally different from an adult microbiome up until weaning. But vaginally born babies also have more maternally-similar microbes than C-section babies. (see here... paywalled, sorry)
posted by en forme de poire at 11:37 PM on May 1, 2016 [4 favorites]


That gets me thinking about cancer as a parasite. A descendant of one of our cells becomes different enough from the rest of us that it forms what is, in some ways, a new individual. If it's benign, it becomes a parasite that's along for the ride, sucking up resources without killing us. If it's malignant, it's a destructive (and self-destructive) parasite that eats its host from the inside out, ultimately killing itself, too.

Not necessarily? The descendant cell doesn't have to differ much in terms of its identity, it just has to end up with few basic housekeeping genes stuck in the "on" or "off" position. There's a selection process in out-of-control cellular reproduction that shapes malignancies towards certain types of behavior, but the fundamental difference in the progenitor cells can be quite small. Our immune systems are fine-tuned to recognize certain signals that our cells have become cancerous, but the differences between cells transforming into a malignancy and cells functioning normally can be much smaller than the differences between us and any fellow human, even a human related to us. Which doesn't mean there aren't cancers where the tumors end up with whopping alterations to their genome, with missing pieces and entire missing or duplicated chromosomes, that make them something definitely not human, but cancer is a generic term for a whole lot of diverse diseases.
posted by gingerest at 12:22 AM on May 2, 2016 [4 favorites]


you know, I want to read the article so that I can comment intelligently and then my eyes get stuck on the words breathing hole and I'm noping the fuck out again
posted by angrycat at 12:28 AM on May 2, 2016 [1 favorite]


OMG, I love that there enough parasitecists(?) here that they're debating each other on the attributes of parasites.
posted by bendy at 2:04 AM on May 2, 2016


I'm just shocked the article failed to mention the dead goat.
posted by Joseph Gurl at 3:05 AM on May 2, 2016 [3 favorites]


Note - nail polish over the botfly hole also works to entice them to get the hell out of your flesh. This is why I always bring my sparkliest nail polish to the rainforest!
posted by ChuraChura at 5:24 AM on May 2, 2016 [9 favorites]


gingerest: The descendant cell doesn't have to differ much in terms of its identity, it just has to end up with few basic housekeeping genes stuck in the "on" or "off" position. There's a selection process in out-of-control cellular reproduction that shapes malignancies towards certain types of behavior, but the fundamental difference in the progenitor cells can be quite small. Our immune systems are fine-tuned to recognize certain signals that our cells have become cancerous, but the differences between cells transforming into a malignancy and cells functioning normally can be much smaller than the differences between us and any fellow human, even a human related to us.

You make a number of great points. (I probably should've just quoted your whole comment, since it's all great.) Like you say, the minimal number of mutations required for a cancer to develop is much smaller than the difference between related individuals. But... but... I'd suggest that the genes which are mutated in a cancer are exactly the ones that you'd have to mutate in order to change behaviour from cooperative to self-interested, i.e. exactly the ones that make the behaviour of cancer cells more parasitic than the behaviour of a typical fetus.

Cancers aren't technically parasites, just like fetuses aren't parasites. But they both have a bunch of parasitic features. And I'd suggest that any given cancer is closer to a parasite than a fetus is because the genes that get mutated to create a cancer are the genes that encode for intercellular altruism. "Housekeeping" usually means "sacrifice my life for the good of the whole if I might become cancerous", at least for tumor suppressor genes. A placental fetus can be expected to still have genes from the mother that tell it to cooperate if the mother decides to spontaneously abort it. I'd suggest that a placental fetus is only as parasitic as a cancer if paternal effect genes completely override maternal effect genes and thereby cause the fetus to stay alive and growing even if the mother tries to abort it.

But I'm no expert. :-)
posted by clawsoon at 6:55 AM on May 2, 2016


I strongly recommend everyone run a Google image search for human botfly

mods pls ban thx
posted by Aya Hirano on the Astral Plane at 8:06 AM on May 2, 2016 [3 favorites]


and so on aren't interesting when they're happening to women.

As for the article author, I couldn't say, but given that Coyne has literally written a book on speciation, I'm pretty sure this angle does not escape his interest.

(One indicator of whether male and female animals are same, or just closely related species, is whether they can have offspring that are themselves fertile: That mules and jennies are sterile show that horses & donkeys are different species. Wolf+dog crosses can have pups apparently, so dogs *are* wolves.)
posted by one weird trick at 10:07 AM on May 2, 2016


one weird trick: (One indicator of whether male and female animals are same, or just closely related species, is whether they can have offspring that are themselves fertile...

I'm not sure why speciation matters here, since intraspecific parasitism is a thing. (There are even some interspecific parasites which may have started as intraspecific parasites.)
posted by clawsoon at 11:26 AM on May 2, 2016


I read somewhere that when they look at DNA very closely they can recognize lots of fragments that are actually there because millions of years ago different viruses wormed their way in and merged with our proto-ancestor - and that there are viruses still working on similar projects. There are thousands of these little stretches of adenine, guanine (Does that have the same root word as guano?), cytosine and thymine, which form a pattern that can be recognized as being technically foreigners, the way a member of the First Nations is technically a foreigner here in Canada since their remote ancestors were really native to Africa.

The remote ancestor of a mitochondria was a uni-cellular being similar to dysentery bacteria whose means of getting food was to burrow into other unicellular beings, disrupt their metabolism and cause them to burst. But somewhere along the line they burrowed into a cell that had a tougher membrane than her sisters and they have been trapped (happily ensconced) in there ever since.

Meanwhile the guileless chloroplast was a unicellular critter that figured out how to extract energy from sunlight and turn it into sugar, promptly turning it into all the other cell's favourite menu item. It got swallowed by something that intended to digest it, but the chloroplast that survived had the really tough cell wall this time and it survived to settle down glumly in in its prison (gasped in relief because it was now protected within two cell walls) to live out the millennia.

It's not just within the DNA, we also have parasites that have been colonizing us for so long we have cunningly evolved to become dependent on them so that if by chance they were to be stricken with a very selective plague, their loss would mean that we would die of infection, or fail to reproduce (bacteria that produces pheromone scents) or lose our eyelashes and our vision with it, or die of malnutrition, or any number of other misfortunes that don't befall us because we have delegated vital functions to our passengers.

As far as I have been able to gather from reading biology books we are rather like what happens when a kid gets a nice set of play clay with six tubs, each with a different bright primary colour: six months later when all the clay has been combined, separated, combined, separated, thickened with lint, thinned by being sucked, daubed with poster paint, re-hydrated to soften and finally priced out from between the metal ripples in the radiator with a butter knife; It ends up a dismal grey purple colour in which, if you have sharp eyes you can spot some flecks of yellow that have not been entirely absorbed.

(This is also what I think about when I read Genesis 2:7: Then the LORD God formed a man from the dust of the ground. I expect He also made an orangutan with a banana and what He had hoped would look like a duck except it kept falling over, and stuffed a wad of the clay up His left nostril, before smooshing the lot together and making a pair of bipedal mammals with a negligible amount of fur. Tu creasti, Domine.)

You were colonized by stray cells out of your mother's body as if the placenta were the Mexican border. The reason you didn't like that last boy you kissed was because the bacteria in your mouth didn't like the bacteria in his mouth; I don't know how it happened but your oral bacteria convinced you that you felt meh about him. Another lot of bacteria in your mouth told you that batch of beans tasted bitter;Except it didn't: the bacteria turned bitter on contact with the food and that in turn warned you that you were munching on something under-cooked that would lead you to gastric distress if you kept eating.

The longer you co-exist with something the more chances you have to find a way to exploit it and visa versa. AIDS started out as quickly lethal. But those strains that didn't make the host too sick to go on a hot date got to be promiscuous and have lots and lots of descendants. It's in the AIDS virus's own interests to make you live as long as possible and infect as many people as possible. The best way to do this is to become harmless. In another three hundred years the virus will plausibly mutate into something that doesn't require you to take drugs to survive. Green monkeys have already reached that stage of mutual tolerance. Most of 'em have it and don't care. Give AIDS another million years and it will be so cozily ensconced in the human immune system that doctors will measure your viral load to test how strong your immune system is. If your AIDS count is low it will become as discomfiting news as hearing that your T-cell count is low is now. Since AIDS can't survive for long without a nice nutritious host, evolution will put pressures on it to become a good tenant. The next thing you know it's going to start cooperating with the landlord, and negotiate a cut in the rent for acting as the janitor.

Physics, LSD and religion all assure us that we are not discrete beings. Let's say you look at one of my skin cells. You could clone another Jane the Brown using it, so it is surely a part of me. But what about one of the dead skin cells on the outer layer that has not fallen off yet? It's dead, so is it part of me? How about if you could still use it to create a clone of me? How about if it has fallen off me and is on the floor? Where does the border of Jane the Brown end? At the outer measurable limit of the electrical field that surrounds me? When my last descendant has forgotten my name? What about a living skin cell that has damaged DNA so it can't be clones but is still doing its job? Where ever you place that border will be arbitrary.
posted by Jane the Brown at 1:29 PM on May 2, 2016 [8 favorites]


So why is the parasite tongue forever an outsider? Just because it happens to have legs and eyes?

No, it's because he'll not get a majority of delegate votes before July's convention.
posted by storybored at 10:16 PM on May 2, 2016 [2 favorites]


"OMG, I love that there enough parasitecists(?) here that they're debating each other on the attributes of parasites."

Wait until you know some parasitologists, or at least someone doing research involving parasitology. They make great dinner guests!
posted by Ivan Fyodorovich at 11:06 PM on May 2, 2016 [3 favorites]


I just learned that it looks as though a fetus, in order to protect itself from the mother's immune system, tries to turn up the anti-parasite immune defenses of its mother and turn down the anti-viral/anti-bacterial defenses. The fetal cells are presenting proteins from the father that are unfamiliar to the mother, which makes the fetus look something like a bunch of virus-infected cells to the mother's immune system. So maybe the "fetus is a parasite" metaphor misses some of the fascinating low-level biological detail.

(In technical terms: Fetuses produce large amounts of IL-4, which influences maternal immune cells to become Th2 cells, which in turn influence B cells to switch to parasite-fighting IgE production. More cells switching to Th2 means less cells switching to Th1; Th1 activates the infected-cell killers, which fetuses have some interest in repressing.)
posted by clawsoon at 11:27 AM on May 24, 2016 [3 favorites]


Turns out the anti-viral stuff is also used to fight cancer, and a fetus also looks a lot like a tumor to the immune system. So getting pregnant when you have cancer (or getting cancer when you're pregnant) makes the cancer worse.

/derail
posted by clawsoon at 5:06 PM on May 28, 2016


"Heaven and Earth give themselves. Air, water, plants, animals, and humans give themselves to each other. It is in this giving-themselves-to-each-other that we actually live. Whether you appreciate it or not, it is true."

Kōdō Sawaki (Also "Homeless Kodo"; 1880 - 1965, 20th C. Japanese Sōtō Zen teacher.
posted by sneebler at 5:56 PM on May 29, 2016


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