Buckle up folks, it’s a long one. Perhaps my longest yet.
I decided to spend some time focusing on this concept and since I felt it was almost there, but it just needed a bit of detail to essentially be game ready. There are so many concepts in this similar state - almost there, but not quite yet. So I’ve decided to focus on these concepts in an effort to help make Thrive great. So expect perhaps even more long posts. You’re welcome.
Environmental tolerances can wildly vary across Earth, let-alone any sort of alien planet. Everything from sunlight, oxygen, pressure, salinity, pH, temperature, and any other environmental factor has a significant influence on the metabolism of organisms. In light of this, Thrive should focus on discerning which mix of environmental conditions to account for. This list of conditions will be as small as it can be to ease the burden placed on both the development team and the player, but large enough to introduce tradeoffs so that the diversity of life can be adequately represented.
I honestly think that for the Microbe Stage and for most of Thrive, we just need to account for 4 environmental conditions for a minimally-viable product…
Pressure: Influenced by the force – or lack of force – applied by the atmosphere and the ocean on a creature. In the deepest parts of the ocean, the pressure can crush an organism, while on the tallest mountain peaks, the lack of atmosphere might suffocate an organism.
Oxygen: Oxygen can screw atomic structures up, representing a danger to any metabolic system. Bacteria are oftentimes divided based on whether or not they are anaerobic or aerobic. Important for Thrive, as a significant evolutionary moment in the history of our planet involves the transition of biota from being accustomed to anaerobic environments to aerobic environments.
Temperature: Heat and cold will kill, but certain species thrive near underwater volcanic hydrothermal vents and in the freezing poles of the world.
Salinity: Saltwater can be dangerous to organisms unable to properly dispose of said salt, while freshwater can be dangerous to cells who are finetuned to maintain homeostasis in saltwater.
Note - I am a bit skeptical of salinity being necessary, but since it is such an important and universal aspect of cell homeostasis universally, I’ve included it; also, freshwater and saltwater life is an important distinction in life and microbiology. Some may also notice that I have neglected sunlight, which can be extremely catastrophic for certain unaccustomed organisms. But I feel that the other environmental tolerances I’ve listed will eventually effectively simulate the same sort of dynamics at play on Earth. By that, I mean that I think simulating things like oxygen content will naturally simulate the development of tolerance for sunlight, as creatures who are intolerant of oxygen will eventually be relegated towards the depths of the ocean just as organisms intolerant of sunlight would be. Because of that, sunlight tolerance might be adding too much fluff to Thrive, but by all means, we can quickly create a concept for that if it is deemed necessary.
Organisms deal with these environmental tolerances mostly through their morphology and through creating enzymes to combat extreme environments. The way organisms employ enzymes varies immensely, but in regards to environmental tolerance, the common trends are either…
Type A - Creating a bunch of an enzyme which creates things that in some way cancel out a harmful factor. Toxin-resistance works like this, but oxygen and salinity are the two environmental conditions also dealt with through this method. For oxygen, certain enzymes create molecules which basically cancel out excess and potentially catastrophic oxygen, and for salinity, certain enzymes create solutes which might blend with sodium.
Type B - Developing enzymes which operate best in “abnormal” situations, at the cost of producing enzymes which work best in “normal” conditions. So for example, cold-water fish utilize enzymes which operate best in colder temperatures, and thermophile cells use enzymes which operate best in high temperatures. Temperature and pressure tolerance works like this, with pressure-related enzymes creating proteins which can tolerate and work best under duress and temperature-related enzymes facilitating reactions. This effectively makes “ranges” of tolerable conditions instead of a flat “everything is tolerated up to this point” like in Type A.
The first type of enzyme is pretty easy to understand – the more of them you have, the more tolerant you are. The second one deserves more explanation, as it has more implications on the lifestyle of the organism since said enzymes work best in ranges, and are thus more consequential in determining habitable ranges.
Utilizing the second suit of enzymes, organisms generally display three levels of adaptations towards environmental conditions…
x-Tolerant: Species are unbothered by the presence of said environmental factor unless the factor is overwhelmingly present.
x-Philic: Species perform optimally in the presence of said environmental factor and are more tolerant to high levels of the factor, but still suffer from the most extreme of conditions.
Obligate x-phile: Also referred to as “extreme -philics”, obligates can only survive in the presence of said environmental factor, able to tolerate even the most extreme of conditions.
For example, lets look at pressure. Barotolerant organisms can tolerate high pressure more than the average organism can, but not to an extreme amount and generally prefer the absence of high pressure. Barophilic organisms prefer high pressure environments and have a heightened tolerance relative to barotolerant organisms, but still might not be able to manage the depths of the ocean. They also begin to operate less efficiently in lower-pressure enviornments. An obligate barophile, meanwhile, can only survive in the presence of high pressure, and perform very well in extreme environments, such as the ocean depths.
Furthermore, these different levels of affinity denote different levels of optimal functioning, and thus, different habitat ranges. Again, a tolerant creature still performs optimally in the absence of whatever it is tolerant to, so although it might have a greater tolerance, it is not completely specialized. A philic creature is adapted to the point of it preferring environments which have heightened environmental conditions at the cost of efficiency its normal habitats. And an extreme phile or obligate depends on a high level of an environmental factor to survive, suffering in more normal ranges. The chart below helps explain this…
APPLICATION TO THRIVE
Knowing this can make it easier for Thrive to simulate environmental tolerance. For enzymes correspondent to salinity or oxygen, it’s as simple as having different levels of tolerance which just add onto each other. And for the second type of enzymes correspondent to pressure it’s as “simple” as prescribing ranges of environmental compounds, developing a trait for each environmental factor and various levels of said trait representing a tolerant, philic, and obligate-level, and having organisms outside of their optimal zones have negatively affected ATP output.
Currently, concepts on the development forum show that these tolerances, and potentially other complex organism traits, will be addressed through a sort of “slot” system, in which the player will choose from various traits (represented as enzymes), limited by the space on the player’s genome. Demonstrated in this concept:
Such a concept presents an ingenious method of dealing with environmental tolerances and other complex considerations evolution must oftentimes account for. You can spend points to unlock a tolerance, and then upgrade that tolerance into whatever level you desire. Environmental enzymes can have upgrade levels. The first type of enzymes (the more you have the better tolerance) are pretty simple to represent, with an upgrade simply increasing the amount of tolerance you have. The second type of enzymes (different concentrations indicate different habitable ranges with tolerant, philic, and obligate levels) are just a bit more difficult to understand, but different upgrades will basically indicate different patches your organism can live in. So a level 2 pressure organism (barophilic) would prefer living in a certain range, a level 1 barotolerant organism would prefer a certain range, etc. The more upgraded your protein, the more slots it takes up in your genome – so players are encouraged to pick and choose what they want to be.
At this point, I think the concept is robust and basically perfect for the microbe stage, but then I think we start running into problems when we consider the future stages of Thrive. I had a certain amount of it thought out with what I think is a cool idea, but it left me in a predicament that I wanted some feedback on. Let me explain.
I first bumped into a bit of the problem when I considered the fact that certain traits are basically going to be always selected on most playthroughs. For example, with oxygen-tolerance being an enzyme-related tolerance, at a certain point, the player will place the oxyenzyme down and never take it off unless they want their species to go extinct or be relegated to the depths of the ocean, which might be bad news for progression. So that basically means that a certain amount of slots will be constantly taken and the player will pay no attention to the concept in the later stages as certain environmental factors become stable. Then I thought about mitochondria and how they kind of imply and rely on the oxyenzyme, which opens up a can of worms – are mitochondria conditional only to organisms who have that enzyme, and are they greyed out without that enzyme equipped, etc. etc. But then I looked further and realized that many environmental tolerances will run into a similar situation. The high-pressure enzyme overlaps with shells and compact morphologies and things like that, the high temperature enzyme overlaps with scales while the low temperature enzyme overlaps with fur, salinity will overlap with morphology of gills, and all that sort of stuff.
Basically, certain morphological traits or parts will come with their own environmental tolerance buffs/detriments which modifies the amount of space an enzyme takes up in your genome. For example, consider oxygen and metabolosomes/mitochondria. We’ll say that the metabolosome comes with the level 1 effect, an upgraded metabolosome comes with the level 2 effect, and a mitochondrion comes with the level 3 effect. If you place a metabolosome, you automatically get level 1 and your oxygen-enzyme shrinks by 1. So level 3 would take up 2 slots now, and level 2 would take up 2 spots. If you place an upgraded metabolosome, your creature automatically becomes aerophilic, and level 3 would take up 1 slot now. If you place a mitochondrion, your creature automatically becomes an obligate aerobe, and the oxygen enzyme won’t be accessible in your gene library.
This frees up space in your gene library for other enzymes to put in. So if you were eyeing to expand your capabilities of tolerating high pressure environments but couldn’t before because the oxygen enzyme took up too much space, now’s your chance. But keep in mind that these statuses are dependent on the parts in your cell/organism – if you remove a mitochondria or upgrade it in a way that makes it less aerobic (as some eukaryotes have), you might lose a level of tolerance. You can apply the same concept to various parts – gill upgrades in the future will deal with salinity, fur and scales will deal with temperature, armor and compact skeletons will deal with pressure, etc. etc. Keep in mind that a player should ideally also want to place upgrades not related to environmental tolerances on their organism, so they’ll be incentivized to eventually seek out morphology instead of a more artificial genome as answers to their situations to free up more cool adaptations.
Another problem shows up with this solution, however, in a thought experiment regarding the later stages – a player or organism who only uses their genome and not their morphology for whatever reason, resulting in out of place creatures and obtrusively artificial game restraints. Say you as a player edit your morphology in the aware stage to become accustomed to the extreme oceanic depths. You make your skeleton compact at the cost of size, you slow down your metabolism a bit in an effort to deal with a low-resource environment, you reduce your surface-area volume, all the good stuff. You do everything you should and everything that is realistic to deal with intense pressure, making concessions so you achieve the playstyle you are fascinated by. But then, you look around and you see a fat, quick, and gigantic creature that looks extremely out of place which absolutely creams the competition seemingly unbothered by the constraints its environment places on it. Of course, the player would be confused, until they examine the genome of the creature and realize that it gets by just through its enzymes, having a level 3 pressure tolerance – a very cheap trick, and very unrealistic.
Multicellular creatures are capable of more easily visible and complex adaptations, such as fur or scales or a condensed body plan or whatever else to deal with its environmental factors, but a unicellular creature depends on invisible enzymes and proteins and genes to get it through harsh conditions. And the passive enzyme concept accounts for this, allowing players to make cells adapting for harsh environments that isn’t placing enzymes, which as mentioned before isn’t really ideal. But when we start arriving at the point in life’s history where morphological features are what indicates environmental tolerance, what happens to the passive enzyme concept?
Part of the reason that enzymes become less potent is because as organisms become multicellular and develop specialized tissues, it becomes a lot harder than just developing an enzyme to ensure environment-proofing. With all the coordinated tasks going on in a multicellular organism – a circulatory system, a nervous system, muscles, etc. – morphology has to be utilized much more and alongside enzymes to adapt to harsh environments. For example, deep sea fish have proteins composed of a more durable substance than other fish, but even that has its limits – beyond a certain point, severe morphological concessions have to be made to the point that it is made extremely rare for vertebrates to be found in the depths.
There is one way of dealing with this that’s pretty simple, based largely on the above train of thought and existing concepts. NicktheNick mentioned having certain enzymes scale based on certain characteristics of your cell – so for example, an enzyme which can boost cell metabolism based on exposure to the sun would work best with a cell with maximal surface area, meaning the player would want something with a lot of cytoplasm exposed. Along the thoughts of this idea, we can simply have certain enzymes dealing with environmental factors weaken as your organism grows in size, and have that weakening be made so that by the time you are comfortably multicellular, a level three tolerance would effectively be equal to a level two or level one tolerance. So if players want their advanced multicellular creature to live in the depths, simply playing with your enzymes like a cell won’t get you there – you’ll need to make morphological changes to adapt to the environment.
And of course, not every environmental compound should scale with size. I think only the environmental factors corresponding with enzyme type B (the whole tolerant philic obligate thing) should scale with size, so specifically, pressure and temperature enzymes. Things like salinity and oxygen enzymes don’t really scale off with size.
The same can be said for the effects of certain traits – as your creature gets more complex, perhaps the type of membrane you have will become less influential, so you can’t just assume that your calcium carbonate will take you all the way to the multicellular stage unaffected. Then, you’ll have to evolve a more advanced trait, perhaps taking advantage of your eukaryotic capabilities, to reach the depths. The whole idea is to make it so that what works for simple unicellular cells is different from what works with complex multicellular organisms, and I think this does a good job of that.
And with that, I think we have a robust concept.
With all that being said, here is a basic outline of the previously mentioned environmental tolerances, their levels of affinity, and which morphological features act as permanent status buffs conditional on placement…
TYPE A ENZYMES (FLAT UPGRADES)
OXYGEN: Very important to simulate the Great Oxygenation Event, but becomes a bit irrelevant in the later stages as most life gets mitochondria and the environment becomes more stable.
“Normal” Range – (Assuming oxygen will start off below 1 percent?) The default organism will be anaerobic, as life was in its early history. Any decent presence of oxygen will impact your creatures metabolism, which won’t be a factor in the early points of your planet’s history, but as oxygen-product photosynthesis develops and slowly transforms your planet’s atmosphere, could relegate your organism to the depths of the ocean.
Level 1 tolerance indicates an organism that can tolerate small amounts of oxygen (up to 3%), allowing it to deal with early cyanobacteria-dominant environments while being able to maintain metabolism in an environment devoid of oxygen. Takes up 1 genome spot.
Level 2 tolerance indicates an organism acclimated to heightened oxygen content in the atmosphere (up to 10%), and indicates that said organism performs optimally in the presence of oxygen – however, very high oxygen contents still remain potent. Takes up 2 genome spots.
Level 3 – Level 3 tolerance indicates an organism fully adapted on oxygen, able to fully utilize oxygen in its metabolism to generate immense amounts of energy. Takes up 3 genome spots.
Parts Which Help – Metabolosomes and Mitochondria will offer tolerance buffs, and I am assuming that metabolosomes will eventually be built up to through upgrades since oxygen will not be present in the first few generations in a Thrive playthrough. Metabolosomes will offer level 2 tolerance, and mitochondria will offer level 3 tolerance. It just serves to get the oxygen enzyme out of the way since it will basically never be altered again after a certain point. Certain upgrades to the mitochondria, such as a specialized organelle I forgot the name of which functions through anaerobic respiration, can alter the buffs offered by the part perhaps.
Things to Consider – I think this is a very good concept because it brings in the anaerobe-aerobe dynamic in Thrive. Being an obligate aerobe is kind of implied already – if you have mitochondria and metabolosome with no oxygen, you won’t generate enough ATP as a complex cell because your most powerful organelles are useless. But obligate anaerobes haven’t been represented in Thrive up to this point, which becomes a pretty important distinction in phylogeny and taxonomy. With the default being no tolerance, and with metabolosomes and mitochondria having buffs baked into them, we have found a way to simulate this important distinction in morphology without bumping into any design problems.
Also, eventually, the difficulty in morphology shifts from becoming tolerant of oxygen to becoming tolerant of low oxygen environments, such as in the deep sea or on mountain-peaks. And, one more thing, anaerobic respiration efficiency can also become a factor.
SALINITY: As previously discussed, an important distinction in microbiology and marine science is freshwater and saltwater; and in-fact, some organisms are able to tolerate both fresh and saltwater. But honestly, I’m not sure how to represent this since there really isn’t that much intense fluctuation in salinity across the ocean. Bodies of water which are more closed off tend to be more saline, such as the Mediterranean, so maybe there’s room. Perhaps this is something to be dealt with mostly through morphology? I’ll need some help with this.
TYPE B ENZYMES (TOLERANCE, PHILICS, AND OBLIGATES)
TEMPERATURE (SCALES WITH SIZE): Mostly limited to tolerances of the polar regions and hydrothermal vents in the microbe stage, although in the future, the tropics, deserts, mountains, and arctic areas will become very consequential. Also important in that oceans near the poles are colder than oceans near the equator, so perhaps the patch map should have ocean patches with very temperatures. Temperature enzymes also scale with size, but at a rate less severe than with pressure – by late multicellular stage, the highest level of temperature enzymes should allow you resistance to most cold except the ice-caps, and most heat except hydrothermal vents. Temperature enzymes start becoming nerfed first when you reach land, and second, if you develop warm-blood. From there, features, such as sweat or fur, will also be needed alongside high-temperature resistant enzymes and anti-freeze.
Something a bit difficult to grasp with is the fact that temperature fluctuates through a planet’s geological evolution, so we’ll need a way to scale this enzyme considering that. Perhaps they are relative to the planet’s average temperature at a given time?
I’ll need help with what each level will be assigned to in terms of value, but the general thought I think is that there will be two enzymes, one correspondent with heat and another correspondent with the cold. I would think that ultimately, level 3 heat will be the only thing that matters in the cell stage to deal with the hydrothermal vents and hot springs, but the cold will have more consequences. First, the oceans trend towards cold as you approach the poles, meaning there will be certain ocean patches that could reasonably be chilly and that the frozen regions will have opportunity for higher levels of cold tolerance (chionophiles). Second, Snowball Planet events will happen.
Since level 2 and 3 of tolerances include changing the sensitivity of your organism to cold if you are upgrading heat and heat if you are upgrading cold, level 2 and 3 cold tolerance and heat resistance should not be able to be placed at the same time on the genome. Since level 1 of each upgrades don’t necessarily influence tolerance to the other however, I think they should be allowed to coexist to allow things like whales and sharks (although if you guys have better ideas as to how to allow this, let me know – metabolism can relate to this).
PRESSURE (SCALES NEGATIVELY WITH SIZE): More important for aquatic organisms, although can become relevant on land once flight and mountain ecosystems are established.
“Normal” Range – Without any adaptations, organisms will function very well on land, ocean surface areas, and shallow seas. The first layer of the open ocean under the ocean surface patches, unadapted species can manage, but begin to be impacted by auto-evo negatively. Severe drop offs begin as you proceed further.
“Barotolerant” Range – Your organism will still maintain its optimal functioning near the surface patches, but will also have a greater tolerance for the higher-placed open ocean patches and will be able to go down deeper with less impact to metabolism and auto-evo. Tolerance starts tapering off near the middle of the open ocean zone layers. Takes up 1 spot on your genome.
“Barophilic” Range – Your organism will perform very well in most open ocean zones and mid-ocean caves, but the ocean floor and its caves remain treacherous and your organism begins to lose tolerance for the surface patches. Takes up 2 spots on your genome.
“Obligate Barophile” Range – Your organism will perform very well in most open ocean zones and even the ocean floor and its caves, but will lose all tolerance for low-pressured areas like the surface patches. Takes up 3 spots on your genome.
Parts Which Help – In the microbe stage, certain membranes and their rigidity variations (more rigid is more pressure resistant and more flexible is less pressure resistance) can add pressure tolerance. Normal, double, and cellulose membranes will by default have 0 tolerance towards pressure. Chitin membranes will have a default level 1 tolerance, silicon membranes will have a default level 2 tolerance, and calcium carbonate will have a default level 3 tolerance (can be shifted depending on realism, I am unfamiliar with the differences between those three). The rigidity slider can finetune environmental tolerance ranges up to an amount correspondent to a level, allowing you more detail in defining the optimal habitats for your organism. So normal, double, and cellulose membranes can have their tolerance levels finetuned up to level 1 of resistance, chitin membranes rigidity edits can be anywhere from level 0 to level 2 tolerance, silicon anywhere from level 1 to level 3, and carbonate anywhere from level 2 to level 3. This can make membranes even more consequential, which I know has been sought out. Down the line, skeletal adjustments, armor, and other morphological features will take over, and enzymes and cell membrane type will become less consequential.
Things to Consider – First of all, to make sure I am not being stupid, would making something more rigid make it more pressure resistant, or would making something softer make it more pressure resistant? Intuitively it seems like a more solid thing is more able to deal with pressure, but I hesitate only because of blobfish – they become a lot more squishy without a high pressure environment, perhaps implying that they deal with high pressure by being a bit more squishy. The answer to this will dictate whether looseness or rigidity corresponds with heightened pressure tolerance, and I think unless absolutely bound by science, rigidity would make more intuitive sense.
Second thing to consider, should very flexible normal, double, and cellulose membranes have negative one tolerance, making it so that your species is even more sensitive to pressure? And since there is no level 4 tolerance, should there be a cool little “power” a calcium carbonate organism gets if they are as rigid as possible?
Another small thing is that the inverse of high-pressure is also a factor when it comes to mountains and flying. It isn’t really applicable now, so we can come back to that later.
With that being said, some final thoughts. Since you start off in the hydrothermal vents, you’ll obviously be in a pretty high-pressure and hot environment (I will say that hydrothermal vents vary in depth however, so perhaps in the future, the player should start hydrothermal vents which are deep but not very deep). So the player should be a level 3 thermophile and a level 2/3 barophile from the get go. This is a perfect opportunity for a tutorial. For new players, we can introduce the protein library on the first or second trip to the editor. When it’s the part of the playthrough where the player is taught how to move from patch to patch, we explain how the enzymes work – necessary since the player will be going from an extremely hot hydrothermal vent to a relatively cold ocean. We tell the player to drop their level 3 thermophile status into a level 1 chionophile status, teaching players both how to purchase a protein and interact with said protein. If this is deemed too complicated however, we can take some artistic liberties. Perhaps have the starting hydrothermal vents not be so high pressure or something.
But hey, we’ve finally reached the end. Thoughts?