2464: Muller's Ratchet

Explain xkcd: It's 'cause you're dumb.
Revision as of 10:46, 7 July 2023 by FaviFake (talk | contribs) (According to Science Girl, "she is usually distinguished by being clearly a child, both in terms of her behavior or in comparison to the size of the adults around her.". Here, she is as tall as the other women and doesn't talk, so she's Hairbun)
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Muller's Ratchet
Who knew you could learn so much about sexual reproduction from looking at pictures on the internet!
Title text: Who knew you could learn so much about sexual reproduction from looking at pictures on the internet!


In this comic, Randall reviews a passage explaining the internet with terms associated with evolution, comparing the constant resharing and changing of popular photos to evolutionary processes, namely Muller's ratchet and recombination.

An image of Hairbun showing a cat to Cueball, who is apparently shocked, is used as an example of the subject phenomenon. This image is altered in various ways:

  • A caption is added to the photo as a whole, possibly using an online "meme maker" tool. Many memes are made in this manner, such as the Office Space "that would be great" memes.
  • Individual labels are placed on the participants (which include the cat). These labels may be literal, but often they are metaphorical. A common metaphorical example is the Distracted-boyfriend meme.
  • This seems to be unmodified from the original, except being a bit fuzzy. This is likely a comment on how most people, due to being unfamiliar with image formats, will often pick settings when saving a picture that results in the image being compressed noticeably (usually via exporting as a JPG as opposed to a PNG).
  • A caption is added at the top and bottom of the picture, again possibly by an online meme maker, and the photo cropped.
  • A sword has been added to the picture, held in a comical position by a participant (the cat) who wouldn't usually have one.[citation needed] These are typically just done as a joke. This image is also cropped and has its aspect ratio changed.
    • A watermark is added to this image, having been added by "SwordApp" a fictional (as of this comic's publication) app used to add the sword
  • Individual labels are placed on the participants here as well.
  • Individual labels are placed on the main (human) participants only. This might be used to only apply metaphorical meanings to the people and not to the object being held (the cat).

Recombination is the combination of genetic material from chromosomes, shuffling genes during meiosis. In this case, it is being compared to shuffling and recombining aspects of an edited digital image.

Sometimes, genetic mutation can create better genes - like the sword being given to the cat in the image. Other changes remove or degrade from the genetic history, without apparent detriment, just because the circumstances do not currently confer any significant advantage to it. If the 'lost' ability is perhaps useful in dealing with an infrequent environmental stress then the loss of its utility might be felt a generation or two later.

With recombination, useful novel changes can be shuffled into the population without necessarily bringing in a less useful mutation, creating descendents with both the obvious advantages (a sword) and the previously more established resilience (the fuller frame).

The caption in this comic jokes that while the passage is explaining the spread of Internet content using evolution, Randall feels that image memes (like the one shown in the comic) have become so ubiquitous that it now seems more intuitive to instead explain evolution using the metaphor of images on the Internet.

The degradation of digital images has previously been explored in 1683: Digital Data.

The title text has a double meaning, referring both to the ways these particular images on the Internet illustrate these evolutionary processes (which are driven by the mechanisms of biological reproduction, including sexual reproduction) and to the amount of erotic imagery illustrating the mechanics of sexual activity one might find on the Internet.


[A caption sits above a slightly greyed-out photo of Hairbun holding out a cat to Cueball, who has his hand over his face and is leaning away. Below are arrows leading to much smaller variations of the photo, all altered in some way.]
[From left to right: Image with the sides cropped and black text bordered by white in the bottom center; image with black text in white box with black border above cat, on Hairbun, and on Cueball; image identical to the original but with softer edges; image cropped around all sides to exclude all negative space around frame, with white text bordered by black near the top and bottom center; image cropped to cut out half of Hairbun and Cueball's legs and featuring the cat holding a sword out at Cueball; image same as the original except with black text bordered by white on top of the cat, Hairbun, and Cueball; and image blurred out and at low resolution with black text in white oval on top of Hairbun and Cueball.]
Caption above: When a photo goes around on social media, people create lots of new versions of it.
[A larger depiction of an image altered to cut out some of Hairbun and Cueball's legs and the cat holding a sword to the left of a caption, with a faint, shadowed wordmark saying "Made with SwordApp]
Caption: Sometimes, one of the edited versions becomes more popular and supplants the original. But often, the new version isn't made from the best copy of the image. It may be pixelated, cropped, or watermarked.
[The same image appears with a more transparent box around it showing the cropped-out areas and an arrow pointing into it saying "lost". To the left is a caption.]
Caption: As long as those flaws are minor enough that they don't cancel out the big change, the new version can still win out. Each good change brings with it random background damage. The degradation only goes one way. Once an image is cropped, its descendants will be, too. This steady loss of information is called Muller's Ratchet.
[The original photo and the edited replacement are side-by-side, with the original on the right and the replacement on the left. The area above the cat where the sword is shown in the replacement is circled with a dotted line in both images. In the original, the area inside is greyed out, and in the replacement, the entire image is greyed out except for that area.]
[Arrows point from the emphasized parts of both images to a new photo below that combines the original image with the sword from the replacement. The dotted line is still present. A caption sits to the left.]
Caption: But there's a solution. The old versions are still around, so if you have an image editor that lets you splice together parts of two images, you can make a new version with the best parts of both. This process is called recombination...]
[All previous panels are grouped in one large panel, with a caption below the entire frame]
Caption: People use evolutionary metaphors to explain the spread of internet content, but at this point we have so much more experience with the internet that I feel like it often makes more sense the other way around.

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I do this frequently: Seeking out the best quality of two media I've seen put together, in an effort to improve the quality of the resultant combined media.

I had no idea, all this time I'd been creating recombinant PNG. ProphetZarquon (talk) 20:58, 17 May 2021 (UTC)

This is the first time I've encountered recombination, but I've seen the many versions of images scattered across the internet for sure --Wielder of the Staple Gun (talk) 21:33, 17 May 2021 (UTC)

On a number of occasions I've had to edit images given to me to submit to a resource. The original photographer insists on having a 'burnt-on' timestamp directly on the image (he's always done that, and won't accept metadata does the job); meanwhile, the resource's policies are heavily against such 'decoration' and moderators often reject such. When I can't easily clone a 'coverage' area from within the same image - and feather its edges to blend in - I sometimes find another original (but slightly different viewpoint) submitted image that has a sufficiently unsullied 'patch' to let it pass muster. That's a slightly meta-example, I suppose. 23:17, 17 May 2021 (UTC)

Sexual reproduction pictures on teh Interwebz mkay, but I lament a certain underrepresentation of amoeba pr0n. 08:33, 18 May 2021 (UTC)

im guessing this time traveller ^^ just came back from 2008. dont go to 2020. ever. just dont. 14:36, 18 May 2021 (UTC)Bumpf

That's a squirrel?? Look at its tail - squirrels have thick fluffy tails, not that skinny one. And if it is a squirrel, it's by far the largest I've ever seen - unless Hairbun and Cueball are children. I was 100% certain when I saw it that it was a cat. --mezimm 14:53, 18 May 2021 (UTC)

And we do know how Randall draws squirrels: 1503, 1578, 776, and 1156 all contain examples. I vote that this be changed. --mezimm 14:58, 18 May 2021 (UTC)
I'm not sure that's a cat, the muzzle looks wrong to me. Some other feline, maybe. A 4-legged furry mammal with a tail, almost definitely. Could we ask Randall for clarification? 19:45, 18 May 2021 (UTC)
Looks like a rat to me. Maybe a possum or something? It has a pointed muzzle. 20:56, 18 May 2021 (UTC)
Definitely an opossum or other such larger marsupial. Its muzzle is too pointed to be a cat. 02:08, 20 May 2021 (UTC)
It looks like a large city rat to me-have you seen the proportions those rodents can get to?!?https://www.independent.co.uk/news/uk/home-news/giant-rat-found-in-london-gas-engineer-finds-rodent-bigger-than-a-small-child-a6925591.html 42.book.addict (talk) 21:02, 2 February 2024 (UTC)