So I was curious to hear what the state-of-affairs is with regards to the Multicellular Stage. It’s because I have some rough proposals myself that I’m (for now) considering writing up somewhere, but I also don’t wanna rain on anyone’s parade. I could try to summarize current proposals on the wiki somewhere (talk page or dedicated future concepts page), if you’d like, and then mix in my own. I can see Buckly has already done a write-up, so maybe I should wait until he’s finished the wiki page on the topic here:
Whereas these proposals are interesting and well-thought through, I think you’d be interested in hearing me out, because I think we can introduce some relatively simple principles that do not only reflect the science to a reasonably high degree, but are also both powerful and versatile enough to be programmed. A lot of this will basically follow the highly simplified, yet accurate summary of the state of affairs I present in both my previous video and the upcoming one in the “Alien Biosphere Evolution”-series.
So far as concrete ideas (that have been recently been kept alive) for the multicellular stage are basically:
A new organelle binding agents are added (probably locked behind the nucleus)
When you have binding agents you can enter binding mode where if you touch another cell of your species you get stuck together.
When cells are stuck together they share their compounds and get some other bonuses.
Everything else still works the same that when you reproduce you start off again with a single cell.
Eventually once you get enough cells together at once, you could then get on to the multicellular “proper” and start making specialized cells. And get some other reproduction strategy than budding.
I’d be interested to hear if you have something to add to this, or if you want to discuss the later parts of multicellular. So far only the transition to multicellular has been discussed recently as that should be strived to be included in the game before everyone gets carried away by planning farther off future features.
I have not touched any of the multicellular pages, and am still working on the microbial stage one. After that I am likely going to work on the pages for the development teams so if you want to fill out that page, by all means go ahead.
All right, good to know! My video on body patterning is a week or two away still, so I will use this period to mull over ways to apply its subject matter to the multicellular stage. The good thing is that writing for the video forced me to generalize and simplify current insights on the developmental biology of metazoans, from cnidarians to vertebrates. I think this will help boiling it down to concepts that presumably will be codeable, computable and playable in the end.
With the regards to the transition from microbe to multi-cell stage, I do have some remarks already. The proposed idea of “catching” foreign cells (even if it is the same species) and incorporate these into a multicellular whole does sound like fun gameplay, but I feel it’s starting to depart a little bit too far from biological reality. Obviously, we shouldn’t sacrifice too much gameplay on the alter of science, but I think it’s worth exploring concepts that are more accurate to see if they’re not just as fun/codeable, if not more.
Introducing “binding agents” is the way forward in any case, so I support that. However, instead of catching foreign cells, I’d propose a system of budding through cellular division. I imagine something like this:
Some time after acquiring the nucleus, the player can access the “binding agent” trait.
When “binding agents” are added, the player can then continue to acquire resources for cell division the usual way.
However, instead of going into the cell editor again, after having gathered enough resources, the player can opt for “budding”, meaning that an exact copy of the cell is attached to the parent cell.
I can imagine the player being able select what side the new cell should be added or some such.
When the budding process is completed and confirmed by the player, the new unit can continue in unison, forewarning double trouble in the primordial ocean.
This process can continue until the player has acquired enough cells (and perhaps certain other traits like “junction agents”; see below) to enter the multi-cell stage.
This is perhaps a good example of how a few tweaks can result in something that is both a low-threshold continuation of current gameplay, fun and actually truer to the science at the same time!
I don’t even think we need to go deeper than this, but for interest I can recommend a cursory look at the following article, of which the illustrations and diagrams alone are already quite elucidating:
In animals, there are basically two main types of molecular agents involved in multicellularity:
Collagen (or similar), which is basically “intercellular glue” of fibrous molecules wrapping around and wrangling neighbouring cells together in an extracellular matrix.
Junction proteins which act like rivets going through adjacent membranes tying them together. There are different kinds of junctions, some of which anchor the cells to collagen fibers and others form conduits for sharing resources or even signals and thus enable intercellular communication.
Now, to simplify all of this, we could just conflate it as “binding agents” and that is fine. Or maybe we could fork it into two, as what we perhaps in-game could call “junction agents” (which I already hinted at) give special abilities.
But again: I think the simple little scenario above the horizontal line should already be good enough.
I think this is a wonderful idea Phrenotopian! It has crossed my mind before that this sort of replication should probably lead to multicellularity rather than hunting down other cells to adhere to, and I’m glad that you have proposed this. The only issue that gives me pause is figuring out how best to implement player control over how to shape their organism after dividing or budding before entering the multicelluar stage, but perhaps that will not be needed.
When it comes to having the choice between budding or evolution I would personally prefer it to be connected with the editor rather than an option between evolution or mere reproduction. we could perhaps integrate the budding option within the editor with a potential MP cost or the likes.
I think the adhesion proteins could feasibly tie in very well with previously discussed features such as something like the Slots Concept proposed by TJwhale, or potentially the Behavior Editor.
I have always kind of imagined it this way:
When you have binding agent (or something else that unlocks the ability to add more cells to your colony) You get the option to add a kopi of your cell to your colony in the editor(eventually you will be able to edit them individually or in groups, pretty much the same way as a single celled organism right now) whatever you make in the editor could represent the “mature” version of the organism.
Now when you exit the editor you will play as a “young” version of your organism, which consist of only one cell, the original one (I guess this could be defined in the editor at some point). When you have enough resources to split, you wont enter the editor the same way as you usually would, instead the cell that splits off will attach itself to the original. When all the cells that represent the “mature” version has formed, a new “baby cell” will be ejected from the colony and you will enter the editor again. (Some time way down the line this could lead to somekind of parenting/nesting behaviors. I dont know if this is present among these simple colony type of creatures, but would be kinda cool)
This way you still use the editor to design your creature and simulate a time jump.
I guess evolution points would be much more valuable to this point as i dont imagine it to be “cheap” to add an entire kopi of your cell… I could be wrong though, I just make trailers
The idea behind you starting off not being able to add more cells to your organism just when unlocking binding agents, was about modeling cell colonies / organisms that can still live as individual cells but can also form colonies when they bunch together with other cells of their species.
So with the steps I posted above, the player would first become a species that can form cell colonies, and then evolve to a stage where they can become multicellular and add copies of their cell to their body plan.
I think this design was discussed based on the idea that cells would have likely first evolved to be able to live in cell colonies before true multicellularity.
This is exactly what would happen after the player enters the true multicellular stage (contrasted to the colony phase I mentioned above), and before they evolve other reproduction strategies.
I’m guessing that may be inspired by the fact that sponges (the simplest known multicellular animals) have the ability to reassemble their colonies from a loose collection of free-swimming cells, and sponges have long been regarded as the most primitive of animals (Parazoa). However, first of all, only cells from an original colony (starting from a single founder cell) will reassemble and not coopt random other cells of the same species, afaik. More importantly, modern insights suggest that this may be a secondary adaptation in the sponge lineage and that Ctenophores may be the earliest offshoot, and not sponges. So the simplest animals were perhaps a blastula-like vesicle akin the placozoa.
The process of “budding” as in sticking together right after mitosis is now seen as the path to multicellularity. Spherical choanoflagellates like Sphaeroeca volvox are models of these primordial animals, although other forms also exist like e.g. strings. mats or branches. In fact, it’s apparently very easy to induce multicellular forms in normally unicellular eukaryotes like e.g. yeast, which can be made to form “snowflakes”: https://www.nature.com/articles/517531d
Nevertheless, I’m all for “Why not both?”, so -as suggested- we could have:
The acquisition of “binding factors” enabling catching foreign cells.
This gives the ability to catch foreign cells for extra protection/force
The acquisition of e.g. “junction factors” then opens the door for multicellularity
This will result in an option popping up to add cells to their design
The details of the last step is subject to further discussion.
OK, to adjust and nuance what I wrote earlier: Cellular slime molds like Dictyostelids are able to attain transitional multicellularity by loose cells aggregating into units that can form crawling slug-like forms and stationary fruiting bodies. And that does correspond with the original gameplay scenario of loose cells coming together. Also, this is mediated by cell-to-cell adhesion proteins, i.e. “binding factors”. Still, true animal-style multicellularity departs from dividing cells staying together.
OK, it may be informative with the following highlights from the article:
A. “Multicellular organisms typically develop in one of two ways, either through division without cell separation or through cell aggregation. The first mode of multicellular development is exemplified by organisms like plants, animals and fungi while the second mode, a less common strategy among eukaryotes, is nicely illustrated by the dictyostelid slime molds.”
B: “Many of the multicellular lineages present on earth today evolved from unicellular ancestors with rigid cell walls [like] land plants, fungi, and red and brown algae […]. For these cells, adhesion is a passive process very different from the intimate cellular associations found in animals and Dictyostelids; physical connections are established as new cells form and the resulting attachments between cells are stabilized and maintained throughout life. This type of multicellular development, in which cells divide and remain linked by their shared cell wall, has important implications for the developing organism as the cells cannot reposition themselves after cytokinesis.”
C: " animal cells lack cell walls, permitting them to adhere dynamically and reorganize into complex tissues and organs during development. In contrast, […] a cell wall […] provides structural integrity but prohibits cell rearrangement."
So, in summary, there are two main pathways (A) for achieving multicellularity:
Division without cell separation (plants, fungi & animals)
Aggregration of formerly disassociated cells (dictyostelid slime molds)
And there are two modes (B) of multicellularity:
cell wall linkage (algae, plants & fungi)
collagenous matrix embedment (animals)
The aggregative pathway (A1) is highly transitional and it’s hard to see how to arrive at an integral multicellular that way. The cell wall linkage mode (B1) is much more limiting and rigid and clearly only has yielded passive life forms.
So to boil it down for to something very simple in-game, it would make sense to stick to these phases:
Prokaryotic phase Simple prokaryote-like cell
Eukaryotic phase With the acquisition of nucleus
Aggregative phase Like A1 and with the acquisition of “binding factors”
Multicellular phase Like B2 and with the acquisition of “junction factors”
The latter phase will then set things up for the transition to the MULTICELLULAR STAGE.
I like this plan, as it makes a clear path for progressing forwards in the game:
get nucleus, unlocks binding agents organelle
add binding agents and go around binding to other cells you find
after some condition is satisfied you get the junction (?) organelle
now you can design a body plan that gets filled out with cells as you divide. Once you have filled out the body plan you get to the editor and can modify the body plan. After that you start as a single cell again and start filling out your body plan again
after you have big enough body you can make specialized cell types in your body plan
then once you have big enough body plan, you switch away from the microbe view, and now place tissues instead of individual cells. This will be kind of a hard transition as the cells won’t be drawn anymore, instead the player will only see “big” creatures like themselves
I’m fine with hunting down cells to bind with, but I feel it could get pretty tedious for the player to have to repeat that process several times. Maybe after the first time or two the player will begin producing cells to fill out their bodyplan when consuming phosphates and ammonia instead of simply enabling reproduction. The player could still hunt down other cells to bind with, but they could also produce more cells themselves to help alleviate the potential tedium.
Other than that? I love this plan!
I’m all for diversity of options and there’s no reason for the player to have to bind foreign cells, when they acquire “binding factors”. However, hhyyrylainen has a point in a stepwise sequence of abilities being a common and clear path to progression in gameplay. Nevertheless, I do recall that after every cell editor intermission the gameplay starts with the parent cell being close by. If they’re quick, a player can catch that cell and kinda have a simple “division without separation” already.
I think it has been discussed a lot already, and it has been decided that things will stick around when you go to the editor (unless you switch patches), as otherwise it is a free “get away from a predator” button.
Where might we turn for a first look at what genetic and epigenetic modules are needed to engineer multicellularity? […] Genomic and proteomic analysis has shown that, remarkably, components of many of the genetic systems once thought specific to metazoans and bilaterians […] and thought to be crucial in the development and maintenance of complex forms are present in choanoflagellates […] Some of these pathways (e.g., cadherins) appear to have arisen before multicellularity, were involved in environmental and prey–predator detection, and were coopted during the transition.
A fifth observation, likely to be emergent, is that choanoflagellate colonies appear to form not due to aggregation, but due to non-separation after division (with the concomitant production of a matrix and cell junctions).