They can, that's what we call cancer... it's some of our cells rebelling and deciding to do their own thing, and to hell with the superorganism. Of course that isn't all that smart since the cancer will die when we die, right? Well, maybe not... although I don't know of any documented case in humans, some cancers are known to migrate off their original organism and colonize others! An example of this is the tasmanian devil face cancer... it started on one individual and spread to others, the tumors on all infected devils having the genes of the original individual.
But what about individual cells? Surely the buck stops there and they are individual, indivisible organisms? Not so fast! Cells of all eucaryotes (that's us) contain "organs" (mitochondria) that were once a separate form of life and still have their own genetic code, completely separate from the nuclear genetic code of our cells. Not only that, but it was recently discovered that they are still independent enough that they can migrate from one cell to another on their own.
So, yeah, "individual organism" is an abstract concept that has different meanings at different scales and even at a specific scale is rather fluid. And I think "individual self" (or mind) is like that too, but that's another story...
It happens, although only when we are at a very early stage of development, a time when we share some traits with jellyfish. The growth of an embryo tracks our evolution. If you ever see a dog, or a person (see the model taylor muhl) with a color split down the middle of their body, there is a reasonable chance they joined with a twin in utero. Absent a color split, no doubt many of us are totally unaware that we may contain multiple gene sets.
- A summary of Dan Dennett’s hypothesis that plurality (multiple headmates sharing one body) was common and socially accepted in ancient times: https://meltingasphalt.com/neurons-gone-wild/
- A primer from a few Google engineers who are plural and describe what that’s like, complete with anecdata, failure states, etiquette, suggestions for collaboration, etc: https://www.pluralpride.com/playbook Told through the lens of dissociative identity disorder (generalized) as an intuition pump. Audience is “sympathetic teammates who want to learn more”
- Plural communities, eg https://www.reddit.com/r/plural/top/ - anecdata of everyday experiences communicated through memes
https://www.nps.gov/articles/000/slime-molds.htm#:~:text=The....
>There are two types of slime mold: cellular and acellular (plasmodial). During the life cycle of cellular slime molds, they remain as single cells. When an individual cell encounters a food source, it sends out a chemical signal which attracts others of its kind, drawing them in until they form a mass which is capable of movement in an amoeba-like fashion, with each cell maintaining its individual integrity. The fruiting bodies of cellular slime molds release spores, each of which becomes a single amoeboid cell when it germinates. Cellular slime molds are rarely visible to the naked eye.
>On the other hand, plasmodial slime molds start out as individual amoeboid cells, but join together to form a multi-nucleate mass having only one cellular membrane (a "super-cell" containing multiple nuclei). This mass is referred to as a plasmodium and is frequently observed as threads of "slime" on rotting wood. The plasmodium matures into a network of interconnected filaments, which slowly moves as a unit as its protoplasm streams along the network. These plasmodia can be quite large; some species have been recorded to be over thirty square meters in size!
>Also referred to as myxomycetes, plasmodial slime molds are commonly seen on decaying forest litter and rotting wood. They play an important role as decomposers and recyclers of nutrients in the food web. Their diet consists of the bacteria which feed on decomposing plant matter. In turn, slime molds may be consumed by nematodes, beetles, and other larger life forms. In the laboratory, slime molds have demonstrated the ability to navigate a maze in order to reach a food source, and to anticipate the reward of food at a future time after having been fed on a regular schedule at one location. They communicate via chemical signals to others of their kind. That's pretty impressive for an organism without a brain! They can be found throughout the world, but the Pacific Northwest and Mount Rainier National Park provide ideal habitat for these amazing creatures.
Harvesting, cooking and eating Dog Vomit Slime Mold:
https://www.youtube.com/watch?v=KfbLSl_4o78
>Fuligo septica is a species of slime mold, and a member of the class Myxomycetes. It is commonly known as the scrambled egg slime, or flowers of tan[2] because of its peculiar yellowish, bile-colored appearance. Also known as the dog vomit slime mold, it is common with a worldwide distribution, and it is often found on bark mulch in urban areas after heavy rain or excessive watering. Their spores are produced on or in aerial sporangia and are spread by wind.