Norn Biochemistry 101: A peek inside a Norn

An introduction to Norn Biochemistry. If you're wondering how to best take care of your Norns, this is the definitive reference! This article refers equally to Creatures 2, 3 and Docking Station so, get reading!

-by Lis Morris

What's for Dinner?

So, you've just bought Creatures 2 or 3. You've been saving up for ages. Feverishly you pull it out of the box, and put the CD in the drive. It doesn't work. You go back to the shop, and get a new CD. This one doesn't work. You go back to the shop, and get a new CD-Rom drive, amid many mutters and complaints about the reliability of hardware these days. Finally, the game works. You hurriedly install it, and start to play with your new Norn family. As you raise and breed your new life forms, you learn that various chemicals can be displayed as graphs on the screen. Scratching your head in bafflement, you begin to wonder what all these things do- what is fatty acid? It doesn't sound very nice. What does a histamine do, exactly? Why is that ettin lying on the floor groaning?

These articles may answer some or all of these questions for you. Perhaps the main question could be defined as 'How do these Norns actually work, then?'. One of the features of the Creatures series that makes it different to any other virtual-life type game is that it does not just try to make an animation of an animal that acts like a real one, but it models all the various goings-on beneath the surface that make up all animals and plants in our world.

ATP and ADP - The Key to it All

We have to begin somewhere, and it seems logical to start with the basis of all the Norn biochemistry. ATP, or Adenosine TriPhosphate, and ADP, Adenosine DiPhosphate are the two chemicals that are the fulcrum of the energy system in Norns. ATP is the basic energy unit, and is used up by muscle movements and other chemical reactions. When it is used up, it doesn't disappear altogether, but turns into ADP, which is an energy-depleted form of the same chemical. It is possible to reform ATP from ADP by adding energy to the reaction. So, if you add the amount of ATP and ADP together in a Norn, you'll see that there is always the same total amount of both, but the amounts of ATP and ADP individually will vary. Lots of ATP means a Norn has tons of spare energy, whereas lots of ADP suggests the Norn has been burning the candle at both ends! Some people wonder which one of the two chemicals is the 'bad' one. You'll see that neither is- injecting a Norn with ADP will do no harm- it'll simply add to the pool of ADP waiting to be turned back into ATP. Injecting ATP can give your Norn a much-needed energy boost.

Where does this energy that remakes the ATP come from? The answer is in the Norn's food...

Not Cheese Again?

All living creatures need to eat to live, and Norns are no exception, although they sometimes seem to get it into their heads that eating doesn't apply to them! There are three main important food groups a healthy Norn needs: starch, protein, and fat. You may be surprised to see fat in there- many people think that fat is a bad thing. In fact, it's essential to us as well as Norns. We just tend to eat too much of it in one go!

Different foods contain different amounts of each of these three food groups. In Creatures Two, the amounts can vary within a single type of food- for instance, coconuts and tomatoes have very different food values. Tomatoes contain lots of starch, whereas coconuts contain roughly equal amounts of all three food groups. Carrots have lots of protein and starch, and not much fat. Oddly enough cheese is not fatty as we might expect, but is starchy. Xander fish are nice and fatty if your Norn is a little underweight. In Creatures 3, the nourishment a Norn gets from any food is genetically specified, so it's the same for all food in one category. Fruit is a good source of protein, and also contains some starch. The best source of starch is seeds. The 'food' itself- carrots and cheese- contain fat and protein. You'll notice that older Norns will argue about whether fruit or food is the best source of protein- now you can see why!

But what happens to the food once it is eaten? This is where things get a little complicated, because the paths the three food groups take are entirely different. Let's start with starch. Starch is firstly broken down into glucose, a chemical all sweet toothed people will be familiar with. From here, it is broken down again into pyruvate, a chemical only biologists and the extremely smug will be familiar with.

When glucose is turned into pyruvate, energy is created from the reaction. This energy, as you have probably guessed by now, is used to turn ADP into ATP. It doesn't end there, however.

Next, the pyruvate can take one of two paths, depending on what the Norn is doing at the time. If our Norn is wandering about happily in the air, there's plenty of oxygen about, and the pyruvate is broken down still further into dissolved carbon dioxide, releasing yet more energy. The carbon dioxide is a waste product, and slowly disappears from the Norn's system. However, if the Norn is underwater, there is obviously no oxygen around, so the pyruvate cannot be broken down. Instead, it is changed into lactate.

Lactate is a fairly nasty chemical- it gives the Norn a choking sensation (which is actually a good thing, since if they feel they're choking, they might feel they ought to do something about all this water around them), and causes muscle pain. No more energy is given off when pyruvate is turned into lactate. This is why the Norn drowns - it's not getting the energy it needs. However, if the Norn is placed back into the air, the lactate can be turned back into pyruvate, and used up to make energy in the normal way.

However, if the Norn couldn't store spare glucose in some sensible form, it would need to eat continuously to stay alive! Therefore, glucose is stored in the Norn in another form- glycogen. This forms the most accessible store of energy for a Norn, which is why glycogen levels tend to be the first to drop if the Norn is starving. The Norn health indicator in C2 is dependant on the levels of glycogen.

Protein digestion is a lot less complicated, since it follows many of the same routes, eventually. Protein, instead of being broken down into glucose, is turned into amino acid. Again, amino acid has to be stored as something for long term use, and it is stored as muscle tissue in the Norn. Pregnant females use up a lot of muscle tissue to make their unborn baby, so it's important to feed them with plenty of protein rich foods. How is amino acid used as energy, though? Well, it can be turned into glucose. This glucose then follows the same path as the glucose from starch. The Norn biochemistry does not distinguish between molecules of a chemical according to where they come from- once glucose is made, however it got there, it is used in the same way.

Finally, then, let's talk about fat. Again, fat is broken down- this time into the rather revolting sounding fatty acid. This is then turned into triglyceride, which then is used to make the long term fat store, adipose tissue. Adipose tissue differs a bit from the other long term food stores, in that it can actually be dangerous to the Norn- a very high level of adipose tissue can cause heart disease in the long term. You've probably guessed by now that somewhere along the line, fat can be turned into glucose and used for energy, and you'd be right. Fatty acid can be turned into glucose, and then into pyruvate, and so on.

Summary of Food Digestion in Norns

 
Food Group What is it broken down into? It is stored as...
Starch Glucose Glycogen
Protein Amino Acid Muscle Tissue
Fat Fatty Acids first, then Triglyceride Adipose Tissue


All these above reactions can proceed in both directions. Not only can amino acid be turned into muscle tissue, but muscle tissue can be turned into amino acid. Adipose tissue can be built from glucose. So what stops everything just sloshing about and not going in any particular direction? The fact that the Norn is constantly using up glucose to make energy. Think of it as a series of buckets joined by pipes. The buckets at one end - which would be glycogen, muscle tissue and adipose tissue- are connected to the next ones - fatty acid and amino acid- which are connected to the glucose bucket. As long as the glucose pool keeps being emptied, water from the other buckets will pour into it. But if the glucose bucket overflows, it will refill the other buckets. The only reactions that can't go backwards as well as forwards as the ones that originally make the glucose, amino acid, and fatty acid from starch, protein and fat.

Something hasn't agreed with me...

The question that has bugged all Norn breeders through the depths of time, or at least the depth of the last five years or so, is what to do when a Norn is ill. We've all had the Norn dying mysteriously for no reason, the C2 Norn quietly tucked in the corner with stars around its head that you never noticed before...

Hopefully, this second part of our look under the bonnet of Norn biochemistry may explain some of this. I may be asking questions afterwards.

Norn illness can be divided into three main areas: environmental, infectious, and poisoning.

Glug, glug, glug: Environmental illness

'Even in a virtual world there's real danger' runs the tag line for C3, and it's entirely true for all three versions of the game. The designer who made up the sentence that appears on every box of the game was probably just thinking of those loveable and charming grendels, but in fact there are many other dangers facing a Norn during its life. The environment presents the greatest danger to a Norn's life of the three illness groups: it tends to be either harmless or fatal.

The most universal danger to a Norn's life has to be the simple passage of time. Norns, like all living creatures, age and eventually die. Ageing is controlled by the Life chemical. At birth, a Norn has a very high level of this chemical. It slowly decays over the course of the Norn's life, disappearing from the Norn's biochemistry. When it reduces to a certain point, the Norn ages to the next life stage. Finally, when it reaches a very low level indeed, the Norn dies. By this point, the Norn is old and grey, and has hopefully lived a full and happy life. Ageing can be stopped by fresh injections of the Life chemical. However, the Norn cannot be made any younger- the Norn will simply stay in its current life stage until the chemical has reduced to the point where the next life stage starts. There have been various mutant Norns that don't age beyond a certain point, in fact- either because they are missing the gene the looks at the level of the Life chemical for that life stage, or because they have some mutation that causes the amount of Life chemical to be constantly increased.

This doesn't explain why this section has such a bizarre title. Why 'glug, glug, glug'? What kind of a title is that? Well, another big danger to Norns is all that water about the place. When a Norn falls in water, it can't get enough air. The important part of the air the Norn needs is, of course, oxygen. As you'll know from the first half of this article, oxygen enables more energy to be released from the Norn's food than it can get out of the food otherwise. Without oxygen, glucose is only broken down as far as pyruvate. With oxygen, the glucose is broken all the way down into carbon dioxide, and more energy is made. Just breaking down glucose into pyruvate doesn't made quite enough energy to keep the Norn alive, and its levels of ATP drop. This is one of those proverbial Bad Things: when ATP reaches 0 in a C2 Norn, they become comatose, with stars around their heads. In C3, the results are even worse. The Norn dies. You can't get much worse than that! Incidentally, a C2 starry Norn can be treated with the science kit. There's an injection in there called 'Defibrillant'. If you look at what is in it, you'll see that it gives the Norn a big jolt of ATP, which is pretty logical, all things considered.

We've all experienced the 'eat you stupid Norn' syndrome- the Norn starving to death that simply won't eat. Thankfully, this is far less common in C3 than it was in C2 and C1. In fact, my C3 Norns are so greedy, they eat anything around! Obviously, Norns can die of starvation. When a Norn runs out of adipose tissue, muscle tissue, and glycogen, there's no more energy left to make ATP with, and again, ATP levels drop, with the normal nasty results.

Possibly the most common cause of early death in C3 Norns is a thorough beating by the grendels in the world. When a grendel starts beating up a Norn, the levels of a chemical called 'Wounded' rise sky high. If they get very high indeed, the Norn dies. Norns can also be killed by being hit by other Norns, ettins, the hand, and the sludge gun. Being bashed about can also have longer term effects in both C2 and C3. Falling off ledges and being hurt can reduce the health of the Norn's organs. Some of this damage can be undone by a chemical called prostaglandin. This chemical is a universal healing chemical, and limits the amount of injury done to the organs. However, all injuries do some irreversible organ damage. Eventually, if a Norn gets bashed about once too often, this can actually kill an organ off. The severity of this depends upon which organ is effected. If, for instance, the immune system or spleen is killed, then the Norn will survive, but with no immunity to disease. However, if the heart or lungs are affected, you might as well get writing an obituary. You've probably noticed the 'injury' chemical in Norns by this stage. Unbelievably, injury can be classed as a good chemical. Rather than causing injury, the injury chemical is the Norn's indicator that it has been damaged. Injury chemical in a Norn stimulates healing by prostaglandin production. You could inject a Norn full of injury chemical without any nasty side effects occurring.

Atchoo! : Infections

As if life wasn't risky enough for Norns already, they can also catch various bugs and infections. The mechanism by which life is made miserable for Norns is different in C2 and C3. In C2, the program itself picks a Norn at random and simulates an infection. Infections are far more common in crowded worlds- if you have more than Norns than the world limit of 16, then infections will be very common indeed, and it'll be a rare day that all your Norns will be well. In C3, there are actual bacteria than float around in the air, waiting for a passing Norn to attach to. Most bacteria chose to lurk around in the jungle area, attaching to passing grendels on their various evil expeditions. When the grendel goes near another creature, the infection is passed on. Therefore, keeping Norns out of the jungle, even if there are no grendels in it, is generally a good idea.

When a Norn picks up an infection, its body fills with antigens. Antigens are chemicals specific to the kind of infection the Norn has caught. There are 8 different antigens, numbered 0-7, because computer programmers can't start counting somewhere sensible, such as 1. Each different antigen is converted by the Norn's biochemistry into various nasties. Histamine A and B, for example, make the Norn cough and sneeze. The most evil C3 infection by far is antigen 5, which is converted into the Wounded chemical, and can quickly kill. Antigens themselves are dangerous, too. They can damage organs directly, sometimes killing an organ altogether. Different antigens attack different organs. In fact, careful application of the correct antigens can be used to sterilise an overly 'friendly' Norn!

There is a ray of hope on the horizon- there are ways to combat disease. Norns can build up immunity. As well as all the nasty side effects, antigens are converted into antibodies. These antibodies again come in 8 different flavours, 0-7, one for each antigen. Antibodies attack the antigens, and get rid of them. The longer an infection continues, the more antibodies are produced, until eventually the Norn is immune to that infection. At least, for a while. The hand is not entirely helpless, though, if it's caring for a sick Norn. Antihistamine chemical combats the affects of both histamine A and B, and plenty of food is also a good thing. Injecting antihistamine works wonders, as does the C3 cough mixture. In C2, encouraging the Norn to drink helps reduce the temperature and generally make the Norn more comfortable. If course, if you really want to cheat, you can vaccinate your Norns by injecting them all with high levels of antibodies 0-7.

This looks tasty...: Poisoning

Finally, Norns, just like humans, have to be careful about what they eat. Many otherwise excellent plants contain poisons that can seriously damage their health. In C3, most nasty plants are contained within the jungle area, but in C2, they're scattered liberally throughout the world. The best advice is don't let your Norn eat it if you're not sure what it is! The two most extreme poisons affect the ADP - ATP cycle itself, with disastrous results. ATP decoupler actually turns ATP back into ADP without giving off any energy. I've found this is normally fatal within seconds! Cyanide is also deadly. In C2, it stops energy from food being used to make ATP from ADP, and in C3, it slows down the entire energy cycle. The result is again invariably fatal.

Not all poisons are quite that nasty. Belladonna slows down the heart organ, affecting ATP - ADP reactions, but not to the extent cyanide does. It can be fatal in large doses, but a carefully looked-after Norn can usually recover. Glycotoxin eats away at the Norn's glycogen stores, so that the Norn slowly starves. One way to spot glycotoxin poisoning is to listen to the music track- if a creature with very low glycogen is in view, there's a specific melody that is never heard at any other time. The poisoned creature will also often lie down and groan. Ettins seem particularly fond of glycotoxin laden plants, so they're probably good subjects for your studies. Possibly the oddest poisons in the creatures world are tyrosine and tryptophan. These two chemical are only found in the purple 'badplant' ivy berries on the bridge in C2. They actually cause the Norn to hallucinate. The effect is temporary, and quite amusing to watch in the neuroscience kit.

Some poisons are not from eating bad things, but come from the environment itself. Heavy metal poisoning, for instance, is the result of hanging about at the volcano. Heavy metal damages organs in both C2 and C3. In C2, the bones are degraded- sadly this doesn't result in wobbly Norns, but affects the Norn's ability to produce prostaglandin, the great healing chemical. In C3, the effects are rather more serious: the immune system itself is attacked, so the Norn can no longer defend against all those bacteria I was talking about above. Norns also breathe, and therefore can breathe in nasty things. Carbon Monoxide is a nasty gas that attacks oxygen, making it difficult for the Norn to get enough air to breathe.The final poison for Norns to fear is called geddonase. Norns get poisoned by geddonase if they're stung! The little red gnats in C2, and the various insects in the jungle in C3 inject this charming chemical if pestered by the Norns. Geddonase is not a very serious poison- it reacts with adipose tissue, and destroys it. Since most Norns are overweight anyway, it doesn't affect them too much. However, skinny Norns should watch out!

So, what's the solution if a Norn is poisoned? Luckily, the poisons either slowly decay away by themselves, or there is an antidote that reacts with the poison and destroys it. In C2, most antidotes can be found in the various fruits around the world: gelsemium contains many nice things for Norns, including vitamins and heavy metal antidote. The large, olive-like fruits found in the swamp area are arnica berries, containing the antidote for glycotoxin. One of the biopods contains a blobby purple berry which cures cyanide poisoning, which is fortunate, considering the red badplant berries beside it contain cyanide! Those tiny yellow berries just above that area of the world contain both the antidote to heavy metal poisoning and cyanide. A bargain! However, it's always worth getting the advanced science kit, and simply injecting the correct antidote from the table below.

In C3, things are a lot simpler. If you have a sick Norn, simply use the potion machine to create the right antidote. Time for a table:
Poison Affect Antidote
Cyanide C2: Stops energy feeding into the ATP-ADP cycle, C3: slows down the ATP-ADP cycle Sodium Thiosulphate
ATP Decoupler Turns ATP back into ADP Medicine One
Glycotoxin Destroys glycogen Arnica
Heavy Metals C2: causes bone decay, C3: causes immune system decay EDTA
Alcohol You can probably guess! Dehydrogenase
Carbon Monoxide Interferes with breathing Anti-Oxidant


Only Skin Deep?


Time for a celebration: I've nearly finished! You haven't got rid of me quite yet, though.

Where did this complex biochemical model that is a Norn come from? Well, it came from us! Or from mammals, to be more accurate. Our entire energy system is based on ATP and ADP, we store glycogen in our livers, and convert it to glucose when we need energy. Antihistamines definitely exist- I'm allergic to them. Luckily, I don't get hayfever too. Possibly the silliest allergy in the world, but there we go. As for the poisons, belladonna is the alternative name of deadly nightshade, and you can guess what that does. People who work with cyanide in laboratories keep the antidote by their side at all times. Of course, humans are far too sensible to eat all these dangerous substances. Aren't we? People often compare the creatures game to tamagotchis and other similar virtual pets. While I have nothing against virtual pets, in fact I think they're fun, the similarities are only skin deep. Norns are not an attempt to simulate life, but an attempt to model it, not only in behaviour, but in the deeper levels of the complex chemical reactions that make up who we are. And that is what keeps us all playing...