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**Glak** · May 3, 1999, 23:40

I figured that I'd bring my response over too, I hope it formats correctly.

I haven't read that much history except a book about the Mongols (Ghenghis is my hero). It seems as if their
messanger system spread the plague west where it got a lot of people sick. So while the Mongols spread the
disease they weren't seriously affected. The city folk with their rats and bugs were the ones that died. The
Mongols probably had some resistance but I don't think that can account for it. The book wasn't focused on rats
so it didn't mention anything about them but I think that we can assume that the rats didn't follow the nomads
around. Also the Mongols had low population density except when on campaign. So I think that the spread of
disease is linked to soldiers/merchants while the severity is linked to your rat and filth level.

Maybe you could have it so that with every transaction (war, trade, etc..) you would have a % chance that the
people involved are carriers (based on how many at home are sick, large groups would definently have some
people with the disease) and then you could take that number and subtract a factor (such as resistance or
procedure) from it to get the net disease induced. That way if you have high resistance you could absorb a few
sick people without trouble (assuming that this is how it works in real life) but typically some disease would get
through.

Then you could have another algorithim that calculates the disease within each area. It would do this every turn,
even if there are no diseases in the area currently. The disease would grow or die off depending on sanitation,
resistance, general, health, etc... This part would not handle the spread of disease. If you don't plan on
introducing diseases as prescripted events then this could also be the disease generator. Anytime you get some
sort of negative value for disease reduction (as in disease in the area would never die off, no matter how much
resistance people built up) because everyone is eating raw rats and such then a disease could be generated.

Also war tends to spread disease among armies. If you use something like the above you could view the army
itself as a seperate territory. The carriers can be initial soldiers or the corpses of diseased enemies. The army
could get sick based on its factors. The army would also count as a carrier too so it would get the locals sick as
well as the people back home when the war is over.

**Mark_Everson** · May 4, 1999, 06:13

Thanks for moving your post over too. (Truth be told, Jim Gregors is the one who did all the work to archive this one, I just pasted in his HTML. If everyone would move a few things we could reconstitute the old discussions pretty easiy.) But on to your topic.

I think I've heard an explanation for why the Mongols Weren't as strongly affected by the black plague. (I don't know if its right, just read it somewhere.)

Anyway, the explanation is that they had lived with the plague disease for some time. Although it could still cause serious illness and death among them, as a people they had acquired some immunity thru repeated milder exposures. Probably people with some natural resistance to it had been favored for survival in previous bouts and so formed a larger part of the population too.

Also, since the disease had been around them for some time, they had adapted "cultural defences" too. I don't know the details, but I think when rats started behaving in certain ways, or too many of them came too near a camp, the Mongols would up and move. Rats doing certain things had become taboo, and thru this vague "awareness" of the mechanism of transmission the Mongols were somewhat spared.

**EncinoMan** · May 6, 1999, 02:06

I have always enjoyed the two civilization games developed for Microprose by Sid Meier and have looked forward to the successor of these two games. I am happy to see the initiative you have taken in pushing for the evolution of the game concept to the next level, paying closer attention to how we have gotten to where we are today. The two previous civs have glossed over several key points in the evolution of civilization by skipping key points that were imperative to the development of todays societies. I am glad to see the detail you have taken in the advances needed for the domesticaion of cereal foods and animals. I also have been looking for the successor to the two civs to deal with disease and its undeniable impact on which civilizations were the victors and who have not or for those that survived were incorperated into the winners society. May I point out that before the fall of both the Aztec and Incan empires to Cortez and Pizzaro approx. 10 million died from smallpox leaving the Americas half deserted and even more vunerable to european powers. If you can figure out the logistics of how the diseases will effect the civs involved in the games let me make this suggestion. But before I do I will mention that diseases arose from the domestication of herding animals and the jump of viruses from these communities of one species to our own and consequentially the multiplication of the viruses in the growing communities around the world. I suggest the city improvement of Hospitals. Use hospitals as a deterrent to disease affecting your larger cities and create some kind of wonder like the Centers for Disease Control in Atlanta, that is, if you are going to even have wows. In fact, some civs could use the advent of controlling viruses as a way to conduct germ warfare on other civs if you want to add an equally horrifying alternative to nuclear holocaust.
Going back now to what you found out about the Mongols and the plague is quite true civs learned to cope with a disease by the simple fact that only those who had the genotype that would allow them to survive. Also to be mentioned are the devolopment of cultural taboos. Think about the now developing cultural taboo of safe sex to counteract AIDS and other little nasties.

So finally going back to my earlier point about the Native americans dying in millions is basically what was happening to europe when the taters began to near. I did read a point made about the spread of disease with armies which is very true because disease and famine go hand in hand, but I want to reiterate my point of the viruses conveniantly mutating so they could feed on a new host of specie.....humans.
Other possible ideas that are totally seperate from what I just ranted about is the use of propaganda in war and the media in general on public attitude. I could'nt go with out mentioning the advent of the internet as possible advance and where it might fall under, telecommuications or the computer. Also may want to look at AI as an advance or anti-advance if you have watched The Matrix or The Terminator one to many times. Glad to see someone out there wants change and accuracy, unfortunately it carries a bunch more baggage with it. May I suggest another addition to your possibly growing library on human civilization is "Guns, Germs and Steel" by Jarred Diamond a pulitzer prize winning history.

Good luck on sorting this all out. If I could send caffeine over the web I would cause your going to need it!

**Mark_Everson** · May 6, 1999, 06:16

Hi EncinoMan:

If you're interested there is more disease info in the "rise and fall of civs" thread archive right here.

Cya 'round,
-Mark

**manurein** · May 13, 1999, 15:13

I think you could link Gregor's climatic model to the disease model : microbs and viruses develop better in warm and wet climates, like around the equator. That's why native north american were not decimated by diseases. In the contrary, this why the inner Africa has not been explored before the mid XIX century.

**Theben** · May 15, 1999, 15:39

Actually, native north americans were decimated by diseases. We're still trying to figure out how much was done.

Encinoman(5/6),
Hospitals treat disease after-the-fact, that is, after people are already sick and dying. Public health measures seek to prevent such occurrences & would be the true 'deterrent'.

Mark E, how do you plan to incorporate diseases that rarely affect local populations but are devastating to encroaching ones(the lowland areas of western & central Africa spring to mind)?

[This message has been edited by Theben (edited May 15, 1999).]

**Mark_Everson** · May 16, 1999, 11:25

Theben:

Mark E, how do you plan to incorporate diseases that rarely affect local populations but are devastating to encroaching ones(the lowland areas of western & central Africa spring to mind)?

This is just a sketch, there are few details yet. My plan right now is to model disease resistance on a culture basis. Cultures in Clash need to have pretty good contact within the group to maintain cultural cohesion. These contacts would also be vectors for disease/plague transmission.

Each culture would have a resistance for each disease (maybe 10-15) modeled in the game. Resistance would model both the population's resistance to the disease, and its presence in the general population. On a disease's "home" territory, resistance of the culture(s) to it would be high (and also there would be some background incidence of the disease). In areas that have not see it yet it would be v. low (and no background incidence). When there is no epidemic the resistance is kept track of and when migrants, armies or merchants go out from the civ there would be a chance that they are a carrier for any local diseases.

When they travel/arrive at a destination there will be a chance they'll pass the disease on in their port of call / new home or whatever. If resistance is low we have the makings of an epidemic. Other things like overcrowding, poor sanitation, level of healthcare etc. will affect the chance of an epidemic starting. The epidemic will then diffuse thru the new civ/culture rapidly and have its effects. When it has run its course, the affected culture will have its resistance set to some higher notch on the scale. Different diseases might have different "top" levels to which the resistance can evolve, and different "speeds" for evolution of resistance.

So if European explorers land on a proviously isolated continent like the Americas they will over a very short period deliver a packet of 5-10 types of disease for which there is little resistance. This multi-pandemic would be the Clash equivalent of what happened in the real world. As I understand it the Americas had many fewer diseases to "return the favor" with since population densities were Much lower, and other factors generated fewer plague-type diseases. Jim Gregors is working on some specifics for the models. Everything we do will of course be only a cartoon of the real world, but at least we'll have a rational and self-consistent way for handling disease .

-Mark

**CormacMacArt** · September 1, 1999, 10:25

A while ago I posted the following for Civ III. I think that at least part of it applies here and you can see how I was suggesting disease to be modeled.

E. FALL

More mechanisims must be included as to weaken civilizations.

1. WAR - at present, the only method that a civ can fall.

2. DROUGHT - changing weather patterns would accomplish this.

3. NATURAL DISASTERS - these were included in Civ I and should be returned, but there is no need to make it so that religion can have any power in stopping them.

4. DISEASE - or plague can be caused when two distant civs suddenly come into contact. This causes the effected city to decrease in population by 1 each turn for a random amount of time. The plague has a random chance of being spread through the trade routes on each turn that it is active.

5. OVERPOPULATION - this can cause DISEASE. It would be the result of having a population over 8 or 12 and not having the appropriate city improovement.

6. ECOMOMIC DISRUPTION - trade routes should be severed any time a city is conquered or between two civs at war.

7. POLITICAL INSTABILITY - it is common practise for the AI players to change governments whenever they contact someone they wish to go to war with. I can only assume that human players do the same (I don't). There should be some measure of stabilty that a civ has that deturmines what governments are allowed. This would discourage the constant switching or weaken the powerful civ and allow it to be successfully conquered by its smaller neighbors.

8. IRRIGATION OF DESERTS - after this is done, salt slowly builds up in the soil. At a critical point, plants start to die. This should leave the land unusable for a time.

**Mark_Everson** · September 1, 1999, 19:09

I think we've got all your suggestions covered one way or another.

**Osiris** · September 9, 1999, 03:58

Well, I haven't read any books on diseases. But from a scientific perspective I know excactly what diseases (virus's/bacteria) are.
Basically science and disease are always in a big race, disease to make better diseases through mutation, and science to make vaccines or through most history just keep clean.
Now why not just have two variables for each square, all sguares even where humans dont excist( There have been plenty of virus's coming out of the rain forests lately ).
one is the level for disease in the area, the other is for disease resistance in the area.
Here are the basic rules for what each level the two variables are at...

-disease is the same or 10 below the level of resistance: one unit of population dies, resistance is increased +0.6.
-disease is higher then the level of resistance: one unit of population dies, the concurent squares disease level gets increased by (diseaseV - resistanceV)
-disease is lower than 10 levels below the resistance: nothing happens
*every turn the disease level is increased by 0.5 and the resistance by 0.4

Now for climate/army/merchants etc. changes the amount the disease variable is increased, same goes with medical science discoverys/sanitation the resistance level is increased.

Now there could be addons, like after cars or airplanes are discovered disease spreads like bonfire, but when you could only walk then it doesn't spread as fast. I haven't thought this through yet, but maybe you could have a variable that says every 10 turns it calculates the disease/resistance variable or every 2 turns etc.

This kind of fits on with your model Mark, but makes it more customizable and realistic(from what I can tell) to do it this way. with the resistance level for each square it can also be affected by things like if there culture knows about the disease etc.
I think this model is better because wether you know it or not disease is the worst enemy to mankind right now, and it has been ever since humans were social creatures. This model would give the best customication for the province/cultural and the actual square of population, because disease doesn't recognize any difference in one human to the next, all they see is a host. Also this model is better concerning genetics, just because a sguares culture knows about the disease doesn't mean that their genes majically change to resist the disease, unless you find a cure or common practice to make the resistance high enough.

I just thought this idea for handling diseases in clash in about two minutes and made a rough sketch, criticism invited
But I think the overall model of this will work very well, and you could use it historically too. For example if the disease level is between 1-50 it is the common cold, if its 100-150 its the plaque and so on and so on.

Again I beg the people that are working in this area to fix up my model, but the main idea seems to encompass everything everyone has talked about, if not try and fit it in
[This message has been edited by Osiris (edited September 09, 1999).]

**Osiris** · September 9, 1999, 23:41

Sorry guys, cant do anything with the disease part of the game, wont be sending you that revamped model. But please someone take my place!
I am getting flooded with multiplayer right now so I need to concentrate on that, sorry

**Mark_Everson** · September 10, 1999, 00:26

Hi Osiris:

Well, first of all, there Isn't anyone working on Disease. Jim Gregors took off long ago. But I think we can hammer out the outlines of something reasonable pretty quickly. First, I'll respond to your ideas for a model...

Now why not just have two variables for each square, all sguares even where humans dont excist( There have been plenty of virus's coming out of the rain forests lately ).
one is the level for disease in the area, the other is for disease resistance in the area.
Here are the basic rules for what each level the two variables are at...

I don't think this approach is complete because there isn't One type of disease. So you'd need ten disease values and ten resistance numbers to do it justice. The locals may have evolved some genetic or cultural resistance to one sort of disease, but that doesn't apply in any way to a new disease. By lumping all diseases together your model misses this. The indigenous Americans didn't have Any real resistance to European diseases even thought they surely had some to the indigenous ones.

The advantage your model Does have over the culture-based one I sketched out above is that it handles diseases where the vectors are linked to a certain climate/habitat very well. For example yours does well with malaria since the habitat for the mosquito needs to be there for any malaria outbreak. Mine, conversely does a better job IMO when the vectors either Are people, or move With people, like rats. An example cited above is the Black Plague. I think we need to represent Both types of diseases to have a decent 'cartoon' model of how diseases have affected people throughout history.

-disease is the same or 10 below the level of resistance: one unit of population dies, resistance is increased +0.6.
-disease is higher then the level of resistance: one unit of population dies, the concurent squares disease level gets increased by (diseaseV - resistanceV)
-disease is lower than 10 levels below the resistance: nothing happens
*every turn the disease level is increased by 0.5 and the resistance by 0.4

I get the general drift here, but not the specifics. When you say one unit of population, I think you need something like X Fraction of the population. Otherwise a big city will barely notice any disease. When you say concurent does that relate to the square we're already talking about? If so then it looks like your disease level will explode very rapidly when presented with little resistance. Can you explain further, or even better, work out a quick example.

Now for climate/army/merchants etc. changes the amount the disease variable is increased, same goes with medical science discoverys/sanitation the resistance level is increased.

How do you distinguish between an army etc. of people from nearby, who might have the same resistance as local, vs an army from far away that might have no resistance. Do you use the resistance of the Home of the army?

This kind of fits on with your model Mark, but makes it more customizable and realistic(from what I can tell) to do it this way.

Well, maybe more realistic for some types of disease. How do you model the black death? It didn't creap square-by-square to europe... Armies brought it to cities if I recall.

with the resistance level for each square it can also be affected by things like if there culture knows about the disease etc.
I think this model is better because wether you know it or not disease is the worst enemy to mankind right now, and it has been ever since humans were social creatures. This model would give the best customication for the province/cultural and the actual square of population, because disease doesn't recognize any difference in one human to the next, all they see is a host. Also this model is better concerning genetics, just because a sguares culture knows about the disease doesn't mean that their genes majically change to resist the disease, unless you find a cure or common practice to make the resistance high enough.

I'm not using 'magical' arguments. Evolved resistance (Not Elimination of the disease) can be genetic (single copy of sickle-cell gene is thought to reduce susceptibility to malaria) or cultural (chastity as a defence against venereal disease is among the many I could cite). Also, a locally prevalent disease will be felt through higher infant mortality, which is less costly to society (in purely monetary terms) than a disease that comes in and destroys half the adult population.

What I think we need to do is meld my and your models so we can recognize a reasonable spectrum of how diseases affect mankind now and throughout history. Some diseases should be limited to climate and vegetation, FE limited to jungle. Such diseases generally don't travel, but are a major hazard only for explorers and invading armies. Other diseases should follow people directly. Something like 5-10 Clash diseases, with some limited to terrain type, and others connected to people should do a good job.

IMO The 'habitat' limited diseases should be few, and we might have only one or none for each terrain type. So all jungle might have malaria at some level or other, but nothing else unless it comes with the people as a 'human' vectored disease.

We agree, I think, that technical level in health sciences, population density, health and sanitation infrastructure, vaccination, and probably some other features need to enter into the disease spread/resistance numbers also.

What do you think of my counter-proposal?

**Osiris** · September 10, 1999, 00:45

Mark, I think your counter-proposal is good, I will just add one more level of it that you were talking about - merchants and armys spread disease, to do this they will have there individual disease/resistance factors, and act kind of like a square in this area.
Any way I am rather busy today, so some time tommorrow I will make up a better sketch of my model; I'm sure I can fit the poeple side of disease in there too, and I already have cultural aspects in my first model for things like vaccines/sanitation.

**Theben** · September 13, 1999, 14:23

Mark_E,

Hello again. Obviously I've been away for awhile but I did make a mostly working disease model in the civ3 lists (under MISCELLANEOUS). It's currently geared for civ3 but if there's anything there your team could use feel free to use it.

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Disease in Clash

Disease in Clash

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