“Good - good morning, every creature,” the professor began. He closed his eyes for a moment, let a smile come to his face, and then cleared his throat. “Thank you all for being here for my talk. This is a presentation of my paper, ‘The Impact of Changeling Parasitism on Cultural Evolution of Social Groupings’.”

A slide appeared on screen. The same image from the poster: Chrysalis and Thorax. She snuck a glance at Thorax, who was looking disgustingly bashful, too much in his head to sense her presence.

“I wrote this talk with the intention of delivering it to a lay audience, but please ask me to clarify if there’s anything I haven’t explained fully. Now, a question I and others in my department have had for some time, which launched me into this research project: in the long term, what are the evolutionary consequences of changeling parasitism on the host species?” A click, and the screen image changed to a picture of a louse.

“Let me first briefly define a few things, starting with parasitism. Parasitism is the term used to describe a relationship between two organisms wherein one lives on the resources of the other, in such a way that causes a negative effect. A simple parasite relationship exists between pony lice and ponies, where the louse gets food from drinking pony blood, and ponies get itchy and sick from being bitten. It’s generally in the best interest of the parasite to not outright kill the host, but this can still happen, through overfeeding or through introducing infection or disease, like mosquitoes transmitting marealia and fluffy fever.

Click. The image changed to an illustration of prehistoric ponies using stone tools. “Next, let’s talk about cultural evolution. This is a kind of evolution that takes place not in your genes, but through social change. In many ways it works very similarly to biological evolution - for example, we use our metal tools because the first ponies used stone tools. Nothing has changed about our biology, but we have many thousands of years of skill and knowledge that got us to this point. The differences in pony society structures despite us all being almost identical biologically is evidence of the power of cultural evolution.”

“Cultural evolution can also inform biological evolution; for example, the advent of midwifery has led to more mares surviving foaling, which takes the selective pressure away from mares who would otherwise be selected against for struggling to safely foal.” Professor Eventide levitated a glass of water and took a sip, then changed the slide to a picture of a pair of monkeys screeching at each other.

Chrysalis furtively looked around the room. Twilight Sparkle was on the edge of her seat, taking notes in two notebooks at once; Thorax was watching with eyes half-lidded, interested but already familiar with what was being said; Starlight Glimmer and Sunburst were paying attention but murmuring to each other. What the professor was saying was interesting in the abstract sense, but queens like Chrysalis needed actionable information, not theories about pony lice.

“Parasitism and the burden of parasites can contribute to both cultural and biological evolution. Biologically, we see adaptations like monkeys developing the ability to smell when other monkeys are infected, so they can keep their distance. Culturally, we see adaptations like the development of complex sewage systems to help in breaking the life cycle of internal parasites in ponies. Tracking the impact of parasites in ponies has contributed to multiple medical breakthroughs that have improved our daily lives. You can thank these researchers for the eradication of hoofworm and the low incidence rate today of wing mites, in an example of cultural evolution that has given us an enormous edge over our parasites.”

Click. The image changed to the same illustration of Chrysalis from the start of the presentation. It was strange, looking at a picture of herself with all of her worst enemies. Life threw some unusual situations at her sometimes.

Professor Eventide kept speaking. “With this context in mind, the goal of my research project was to examine any potential cultural or biological evolution that has occurred as a consequence of changeling parasitism. Not just in ponies, but in all recorded species that changelings have preyed upon, since I learned over the course of this study that changeling history stretches back much further than previously thought. I would like to thank Thorax and his changelings for their insight; this study wouldn’t have been possible just a few short years ago.”

Chrysalis resisted the urge to hiss. Thorax giving away valuable knowledge about changeling life was nothing to be proud of, and now it was written down in pony libraries until the end of time.

Still, it was clear that her goal of potentially getting her hands on Eventide wasn’t a bad one; he clearly knew a lot regarding the exact topics she needed to learn about. Even better, like a lot of academics he was too excited about his own work to see danger in someone asking him to follow them for another conversation. All she needed was a way in.

“A brief rundown on changelings, for those who aren’t familiar; changelings are pony-like insects with the unusual requirement of needing to feed upon the social energy known as ‘love’ but which can also consist of trust, friendship, or other positive social bonds, and the unusual ability to magically change their forms to mimic other organisms. An aggressive hive, led by a queen, will undergo excursions in which they will infiltrate the social groupings of other organisms in order to set up situations where they can effectively feed on love. An example of this is the well-known incident where the previous changeling queen, Chrysalis, replaced Princess Cadance in the lead up to her wedding, in order to feed upon not only her fiance’s love but the love that wider Equestria feels for the princess.”

“You may note the presence of Thorax, current leader of the changelings, and how much his and his peoples’ appearances differ from the traditionally known appearance of changelings, as seen in this image of Chrysalis. This relates to one of the key findings of this study: the existence of two different hive states that changelings can biologically experience. For an easy point of comparison, I will describe the life stages of both locusts and aphids, although neither species is particularly closely related to changelings.

Click. A locust appeared on screen. “Locusts are a significant detriment to food stability and economy in Equestria. In their normal form, they are grasshopper-like insects which don’t pose any particular threat to pony life, but under the right conditions, they undergo a physical transformation which causes them to revert to a much hungrier form, which takes flight and can destroy entire fields of crops with terrifying speed. In this traveling form, they reproduce more quickly and need to eat significantly more to survive, speeding up their metabolism to allow them to breed and travel as rapidly as they do. It’s really quite incredible.

“Aphids are also an agricultural pest. They colonise a broad variety of plants and tap into the circulatory systems to suck out nutrients; a good example of crops affected by aphids is brassica crops, like broccoli, cabbage, and kale. Aphids normally reproduce sexually, to introduce genetic variation that lets them survive times of hardship, but when they come across a significant food source, they enter into an asexual phase, where they clone themselves as quickly as possible to take advantage of whatever they’ve found, like a field of potatoes or a meadow with wild mustard in bloom.

The slide changed to a photograph of a wing of changelings soaring over Canterlot. Chrysalis looked at her changelings there. She recognised most of the changelings in the picture; of the ones she recognised, the majority had died either in the aftermath of the invasion or in later skirmishes out of the hive. Of the survivors, they had all betrayed her for Thorax. To the ponies in the room, the changelings in the picture probably all looked exactly the same.

It hurt her to look at so many losses in one image. Changelings were expected to die for the hive, but it was Chrysalis’s responsibility to care for the hive so that they stayed strong and numerous, and looking back through the lens of this image, she couldn’t quite say she had met this responsibility.

Of course, they had failed her too. They had defected, and now they sat together on the other side of the room, tittering and smiling while they watched their leader sell out their secrets to the enemy.

“Changelings are not identical to either of these, but they provide valuable illustrations of what is gained and lost in changing hive phases. We can also compare Chrysalis’s hive and Thorax’s hive to learn a bit more about phase differences. From my time with Thorax, I can conclude that the hive is currently experiencing reduced birth rates and a lower rate of feeding from when the changelings were in their previous form. This lower rate of feeding means that the intracommunity love felt between the members of the hive produces sufficient food to meet the metabolic requirements, meaning that at present, the hive does not need to prey on other species to meet their needs.

This was not something Chrysalis had heard about. She flicked a glance at Thorax, who was listening attentively and without contradiction. It was likely true, then, much to her disappointment.

“My research has yet to conclude what might be the trigger for this biological shift. It does seem to be tied to the status of the changeling leader - Thorax was the first changeling to shift to this passive phase, and his shift catalysed this same reaction in the other changelings. I also know from changeling history that this most recent aggressive phase spearheaded by Chrysalis was originally started by a previous queen, Alate, who changed the hive significantly in the course of her life from a peaceful community with relationships with other species nearby to an aggressive hive.

Chrysalis felt her hackles raise. Alate had been one of the greatest changeling queens to ever live, and she wasn’t sure if she’d be able to tolerate it if she had to listen to some pony professor speak negatively of such a great leader.

The slide clicked over to one featuring a very large dragon. “This begs the question; where was targeted during the aggressive phase preceding the last one? I was very fortunate to have the resources of Princess Twilight Sparkle when attempting to answer this question, and for the first time I can reveal that through conversations with the previous Dragon Lord, Torch, that when his mother was young there was significant changeling parasitism on the dragon community. It is difficult to map this to our pony calendar, but I believe this took place during the Middle Palaeopony Period, approximately fifty-five thousand years ago.

“With this date confirmed by a secondary source, this allows us to delve deeper. Recent archaeological studies arranged in collaboration between Dragon Lord Ember and Princess Twilight Sparkle to allow pony archaeologists access to the dragonlands have published evidence of Lower to Middle Palaeopony dragon settlements that show a degree of architectural collaboration and city-building not present in modern dragon civilisations.” The image changed to a group of ponies at some kind of dig site, surrounded by the remains of very old, large buildings.

“A key question raised by this archaeological expedition was why the dragon culture shifted over time to more individualistic approaches to community, without major collaborative building projects. It’s worth mentioning that this doesn’t seem to have impacted the overall evolutionary fitness of dragons, as they are still numerous and diverse, but this change is interesting nonetheless. This post-city period of dragon history also correlates with the wider appearances of dragons in the historical records of other societies, indicating greater dispersal of the species at this time.

The image changed to some kind of griffon city. Chrysalis had very little experience with griffins; they despised each other so much that there was nothing for changelings to eat there.

“Put a pin in dragon society, and let’s switch over to griffins. As many of you may be aware, the griffon society, centred in Griffonstone, is currently undergoing a reformation after a long period of disarray following the end of the monarchical system. The actual cause for this disruptive period is hotly debated; while the prevailing history theory is that the absence of the relic known as the Idol of Boreas had magical properties that tied griffons together, this has seen pushback in recent years due to counter evidence provided by Equestria’s own Rainbow Dash and Pinkie Pie, showing that the cultural construct of the Idol may have been the binding force, rather than any inherent properties the Idol possessed.

“Furthermore, with the restoration of some long-neglected parts of Griffonstone has come the restoration of parts of the royal archive which record pervasive social unrest during the reign of the penultimate and the final griffon kings, indicating that the social dissolution at the end of the royal period may have coincided with the loss of the Idol, but was not caused by it. Most excitingly, the royal records also contain accounts of significant conflicts between the royal army and quote-unquote ‘most despairful insectoid ponies’.”

Click. The slide changed to a griffon, a dragon, and a changeling, all pictured together.

“In my work I suggest that the long-term parasitism of changelings on griffons during the late royal period was a key factor leading to the social unrest that ended the griffon monarchy. Further evidence from griffon archives is presented in full in my paper. Specifically, under the assumption this conjecture is true, I would like to examine this phenomenon from an evolutionary perspective.

“Changeling predation is usually not fatal, but can lead to significantly reduced evolutionary fitness, as it drains hosts of energy and love required to gather resources and form social bonds for reproduction. Individuals heavily drained by changelings are unlikely to reproduce and pass on their genes, but are also unlikely to culturally contribute due to the emotional and psychological impacts of being fed upon. Over time, I think it’s reasonable to assume that changeling parasitism could have impacts on the biology and culture of a society. In the case of griffons, I am hypothesising that the weak interpersonal bonds and inter-griffon aggressive that characterised the post-royal period is a form of social immune response to changeling feeding; that is, by culturally becoming less loving, griffons were able to make themselves less appealing for feeding.”

Now that was interesting. Chrysalis had always known to avoid griffons for exactly that reason. Would ponies, if Chrysalis loomed over them for long enough, become as rude and dismissive to each other as griffons were?

It disgusted her to admit it, but some of what Eventide had to say was worth hearing. It felt even more important that she capture him and take him home.

“Let us return to the matter of dragons. If we consider that changelings may exert a cultural pressure to dissolve complex codependent societies, and we also know that dragons once lived in more structured societies but dissolved this practice around the time of changeling predation, I don’t think it’s impossible that changelings also led to this. Furthermore, I want to argue that ponies have not fallen victim to this change due to both our numerousness and the relatively diluted impact of parasitism - rather than a consistent campaign across all ponies, the changeling activity in this aggressive phase has been sporadic and targeted, such as the Canterlot wedding siege.”

Eventide was not wrong. Ponies were a rich source of food, and part of the reason they were so rich in food was because there were so many different pony cities to feed on. Every time the well ran dry somewhere, Chrysalis had always been able to find someone else. If there was only one city, no matter how large, Chrysalis could imagine running out of food.

Eventide’s thoughts matched her own. The slide changed to a picture of Thorax’s changeling hive. “Now, let’s return to our metaphors of aphids and locusts. I know I’ve made a lot of assumptions in this last part of my talk, but I do think that these patterns of parasitism are key to understanding biological changes in the changelings themselves. Consider the snowshoe hare, and the lynx; in years where hare populations increase, lynx populations rise, until they reach a point where lynx predation outdoes the reproductive success of hares, and hare populations drop. With less food, lynxes breed less, too.”

The taste of hare blood on Chrysalis’s lips, like metal and sugar.

“In times of food availability, changelings need to breed quickly, and eat more to compensate for this, in order to take advantage of the resources available. Therefore, the changeling hive finds an aggressive leader and shifts to their aggressive phase like locusts, and stays in this phase until struggles with finding food or significant population loss pushes the changelings back to their hive. At this time a new, more passive leader will be biologically selected, and will put the hive into a calmer, senescent state, where food requirements are lower. As such, this would explain the varying accounts of changelings given in history. Although it is difficult for me to prove this using mostly historical research, my work with Thorax has lent a lot of credence to these claims, which are also documented more thoroughly in my paper.”

“This talk has married together two major theories I’ve been working on - the two-phase nature of changeling society, which Thorax continues to research to explain how he was selected from his hivemates to lead, and the impacts that these feeding periods have on their hosts. I expect that my findings will be improved upon or even disproved or contradicted by future evidence, and I look forward to the day when we know more about this previously difficult to research topic. I’d like to extend my thanks to the dragon, griffon, and changeling communities for coming together to speak with me and tolerating all my invasive questions about their lives. I’d also like to thank the Princess’s Research Fund for making this work possible.”

Clapping resounded through the lecture hall. Eventide’s talk was done.

Author's Note

The most influential papers for this chapter were:
Invisible Designers: Brain Evolution Through the Lens of Parasite Manipulation
The role of social cognition in parasite and pathogen avoidance