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[Thundercraft]

Doing a forum search, I see that the subject of Polygamy has been brought up several times before in the Suggestions area. However, these conversations and suggestions were made a number of years ago. Two of the most recent topics on the subject date back to 2015:
Where is the Polygamy / Polyandry?
Polygamy

The suggestion of making dwarves capable of being polyamorous (or allowing polyandry / polygyny) seems controversial. However, the main complaint against it seems to be that it would inevitably result in (a lot) more dwarf children, which many players would not like.

Personally, I find this argument weak, considering that we can adjust the [BABY_CHILD_CAP:100:1000] token in d_init.txt. We can adjust both the absolute cap on babies+children as well as the percentage of the fort's adult pop. We could even turn child birth off.

A counterargument would be the possibility of adding a couple more d_nit.txt settings. For one, a new option to switch dwarves between being monogamous and polyamorous (or turn monogamous ON/OFF) could be added. Optionally, another setting might give some control of Fertility. That, or perhaps there could be an option to reduce the requirements of starting (and, thus, increasing the occurrence of) a Relationship or Marriage.

Alternatively, some new tokens in the raws could control such things.

On to my main point: (I only brought up dwarf polygamy because of how it would impact birth rates and because it ties in to my real suggestion below. I otherwise don't much care about dwarf polygamy.)

Why is it that dwarves mate for life? I'd love to see a possibility of a widow or widower remarrying after their spouse dies. Also, I find it silly that dwarves have to be within 10 years of each other's age for a relationship to happen. A dwarf's max age is between 150-170 years, which is about twice that of a human lifespan (IRL). Such a 10 year window severely limits hookups, which I suspect was the main point: It was probably made this way for gameplay reasons - because marriages and births would otherwise occur too frequently for most players.

What about those of us playing Fortress Mode with a modded civ other than dwarves? Must our fortress of humans, goblins, drow or whatever also be limited to mating for life and only marrying with 10 years of age?

I've searched the wiki and looked and looked in the init settings and Raws, but I can not find an adjustment to either of these things. And when I asked in the modding questions thread, I was told (with 99% certainty) that this was hard-coded.

Like Monogamy/Polygamy, I think it would be relatively simple to add a couple of new switches to d_init to adjust whether or not "dwarves" mate for life and to disable the check on age before allowing a relationship. Defaults could be set to leave things at the status quo.

Alternatively, I'd be satisfied if we just had some tokens we could use in the Raws to adjust such things. And I'm certain that I wouldn't be the only one grateful for this, considering how popular mods are that add custom races that are playable (or make other vanilla races such) in Fort Mode. Several of the biggest and most popular mods seem to do this.

Some of us want a higher than usual marriage rate / fertility rate and more dwarf babies - at least for certain experiments or goals. For example, consider Archcrystal: 410 years in a fortress. Everyone currently alive in Sethatos' fort was born there and descended from two dwarves down through 5 generations. He even set up arranging marriages for their descendants with pre-honeymoon suites. Imagine the micromanagement this must have involved, given the aforementioned limitations. (Read the Arranging marriages section of the wiki article on Marriage for details of how slow and tedious this actually is.)

[SixOfSpades]

I was under the impression that the issue of polygamy had already been resolved (at least in theory) by deciding to, as you said, do what should always be done in controversial cases: Write it into the game, but leave a setting in the init files that can disable it, if the player desires. It's how Toady implemented varying sexual orientation, and it's pretty much the only way to please everybody, so I think it's safe to assume that's how he would implement promiscuity--if he chose to implement it at all, of course.

However, the main complaint against [polyamory] seems to be that it would inevitably result in (a lot) more dwarf children, which many players would not like. Personally, I find this argument weak, considering that we can adjust the [BABY_CHILD_CAP:100:1000] . . .

I skimmed back over those threads, and even found an example of this objection in one of my own posts:

. . . the only real problem with applying [polyamory] to dwarves that I can see is that it has the potential to take the typical dwarven married couple--the equivalent of a constantly repeating baby gun--and turn it into a baby automatic rifle.

Let me clarify that when I wrote that, it was with the consideration that if Toady was at the point of tweaking dwarves to have multiple simultaneous sexual relationships, then naturally sexual relationships themselves would naturally have already been fixed. (Meaning, they would actually happen on their own--more on that later.) The baby cap and other raws actually make the situation worse, in my opinion, by allowing a minority of polyamorous males to claim a disproportionate amount of the fort's baby allotment.

A counterargument would be the possibility of adding a couple more d_nit.txt settings. For one, a new option to switch dwarves between being monogamous and polyamorous (or turn monogamous ON/OFF) could be added.

A species-wide boolean would be far too simplistic, IMO. Sure, it's all right for exploring the idea, but I think it'd best be implemented at the Civilization level, as a part of the "randomized civ ethics" package, if / when that becomes a thing. For example, suppose two lines were added to the Init file:
[POLYANDRY:20:20:20:20:20]
[POLYGYNY:0:5:15:30:50]
In each line, the numbers are percentages for the behavior being randomly chosen for each civ during worldgen. They reflect the odds of a society deciding if polyamory (of each gender pattern) is Mandatory, Encouraged, Permitted, Discouraged, or Forbidden. So the settings in the example above reflect a user who wants his dwarven societies to be completely unbiased in the matter of allowing their dwarves to take multiple husbands, but takes a far more conservative view when it comes to dwarves taking on multiple wives. But even this level of specificity can't do the matter justice: It makes no distinction between relationships of Love <> Sex <> Marriage, which I personally consider essential if we want to see this matter really fleshed out. It also makes no mention of homosexual relationships--but then again, it might not need to; a potential lesbian couple might simply make two checks to see if they violate their civ's Polygyny setting, and none against Polyandry.

Why is it that dwarves mate for life? I'd love to see a possibility of a widow or widower remarrying after their spouse dies. Also, I find it silly that dwarves have to be within 10 years of each other's age for a relationship to happen.

I don't think I've ever seen a single user express disagreement with these views. I, for one, would like to see the concept of dwarven divorce, particularly if one partner is convicted of a serious crime or violation of moral standards.

Some of us want a higher than usual marriage rate / fertility rate and more dwarf babies - at least for certain experiments or goals. For example, consider Archcrystal: 410 years in a fortress. Everyone currently alive in Sethatos' fort was born there and descended from two dwarves down through 5 generations. He even set up arranging marriages for their descendants with pre-honeymoon suites. Imagine the micromanagement this must have involved, given the aforementioned limitations.

As Dwarf Fortress stands now, polyamory is not an issue not just because it literally can't happen, but also because even if it could, it still wouldn't. In my experience, dwarves usually don't get married, unless they're practically forced to by the "love prison" setup you mention above. If you took a population-200 fort and then completely sealed it off (locking out all threats and ALL future migrants), you would create an idyllic dwarven paradise, with no work to be done apart from farming, brewing, cooking, and making clothes . . . it's my belief that, if left to its own devices as far as reproduction is concerned, this utopia would die out in only a few generations, because dwarves currently lack any sort of sex drive. Sure, they may "dream of raising a family", and have a Love_Propensity through the roof, but they currently have no mechanism to seek out and woo desirable potential mates. That, even more than "mates for life" and "no more than 10 years apart", is what kills the dwarven race. As long as dwarves consider "a shared fondness for a particular type of leather" to be MORE important than "the survival of one's entire species", dwarven sexual ethics will not represent a sustainable model.

What Should Be Done? In my opinion, love and sex should be long-term needs, that manifest both in a dwarf's Thoughts screen, and in their behavior. Just as a dwarf can feel frustrated over not having practiced their craft(s) in a while, or that it's been too long since they enjoyed their favorite booze, they should feel glum about not having flirted with anyone lately, and actively seek to correct that. (Both feelings & behaviors would be in proportion to their personality traits, of course.) Implement that, and loosen some of their moral strictures, and the average dwarf fort would be a LOT closer to having 30 couples with 3 children each . . . as opposed to the current standard of 3 couples, with 30 children each.

[GoblinCookie]

Why is it that dwarves mate for life? I'd love to see a possibility of a widow or widower remarrying after their spouse dies. Also, I find it silly that dwarves have to be within 10 years of each other's age for a relationship to happen. A dwarf's max age is between 150-170 years, which is about twice that of a human lifespan (IRL). Such a 10 year window severely limits hookups, which I suspect was the main point: It was probably made this way for gameplay reasons - because marriages and births would otherwise occur too frequently for most players.

Mating for life does not actually mean that a creature does not remarry if one of the partners dies.  The reason they presently don't is because the whole system is a buggy placeholder.  The reason dwarves don't marry is precisely to stop them ending up with multiple partners, the system fails to distinguish between living and dead spouses (and relationships in general). 

As Dwarf Fortress stands now, polyamory is not an issue not just because it literally can't happen, but also because even if it could, it still wouldn't. In my experience, dwarves usually don't get married, unless they're practically forced to by the "love prison" setup you mention above. If you took a population-200 fort and then completely sealed it off (locking out all threats and ALL future migrants), you would create an idyllic dwarven paradise, with no work to be done apart from farming, brewing, cooking, and making clothes . . . it's my belief that, if left to its own devices as far as reproduction is concerned, this utopia would die out in only a few generations, because dwarves currently lack any sort of sex drive. Sure, they may "dream of raising a family", and have a Love_Propensity through the roof, but they currently have no mechanism to seek out and woo desirable potential mates. That, even more than "mates for life" and "no more than 10 years apart", is what kills the dwarven race. As long as dwarves consider "a shared fondness for a particular type of leather" to be MORE important than "the survival of one's entire species", dwarven sexual ethics will not represent a sustainable model.

They don't really make friends very easily either.  I think that they don't get married for the same reason, once you have dwarves that are friends they seem to get married quite easily, as we see with the starting dwarves.  But given that they live so long, they do not need to be be in any real hurry to get married and reproduce anyway.  The problem is entirely a problem with how dwarves don't form friends because they rarely meet the same person multiple times in a short instance.

As Dwarf Fortress stands now, polyamory is not an issue not just because it literally can't happen, but also because even if it could, it still wouldn't. In my experience, dwarves usually don't get married, unless they're practically forced to by the "love prison" setup you mention above. If you took a population-200 fort and then completely sealed it off (locking out all threats and ALL future migrants), you would create an idyllic dwarven paradise, with no work to be done apart from farming, brewing, cooking, and making clothes . . . it's my belief that, if left to its own devices as far as reproduction is concerned, this utopia would die out in only a few generations, because dwarves currently lack any sort of sex drive. Sure, they may "dream of raising a family", and have a Love_Propensity through the roof, but they currently have no mechanism to seek out and woo desirable potential mates. That, even more than "mates for life" and "no more than 10 years apart", is what kills the dwarven race. As long as dwarves consider "a shared fondness for a particular type of leather" to be MORE important than "the survival of one's entire species", dwarven sexual ethics will not represent a sustainable model.

I don't think that sex drive is necessarily even a thing.  I think sexuality may instead work more like "see hot lady, get horny" than "need to meet my quota of sexy times for period X".  Things like food and water work that way, you get hungry or thirsty so you go looking for food and water; but I don't think you inherently go looking for sexual partners in the same fashion.  I think that the whole idea that "I have to go find a partner" is basically either a cultural imperative or a form of addiction. 

What Should Be Done? In my opinion, love and sex should be long-term needs, that manifest both in a dwarf's Thoughts screen, and in their behavior. Just as a dwarf can feel frustrated over not having practiced their craft(s) in a while, or that it's been too long since they enjoyed their favorite booze, they should feel glum about not having flirted with anyone lately, and actively seek to correct that. (Both feelings & behaviors would be in proportion to their personality traits, of course.) Implement that, and loosen some of their moral strictures, and the average dwarf fort would be a LOT closer to having 30 couples with 3 children each . . . as opposed to the current standard of 3 couples, with 30 children each.

What is actually wrong with having 3 couples with 30 children each?  Aside from it not being how things presently work, with humans in the real-world. 

[SixOfSpades]

Mating for life does not actually mean that a creature does not remarry if one of the partners dies.

I poked around and, interestingly, was unable to find a clear answer for this. The phrase "to keep the same sexual partner throughout life" is rather vague unless you actually specify whose life. But I'm sure we're agreed that current dwarf behavior is pretty much the most extreme behavior possible. (My favorite is the story of the Miner who threw a tantrum, and fell in love with a dude while literally beating him to death, thus winning herself perhaps the fastest Darwin Award on record.)

In my experience, dwarves usually don't get married, unless they're practically forced to by the "love prison" setup you mention above.

They don't really make friends very easily either.  I think that they don't get married for the same reason, once you have dwarves that are friends they seem to get married quite easily, as we see with the starting dwarves.

That's largely correct, I would refine it only as "conditions that make dwarves likely to become friends will, on continuation, also make them likely to become lovers and spouses." As for the starting 7, they also benefit from the double-whammy of arriving at the same time (meaning, they all Eat / Drink / On Break at the same time) and having no other dwarves to socialize with, meaning it's far more likely that the same 2 dwarves will interact, over and over. As time goes on, breaks and mealtimes get far less synchronous, and there are far more other dwarves to get in the way. (And also, social gatherings are no longer restricted to the immediate environs of a wagon.)

I don't think that sex drive is necessarily even a thing.  I think sexuality may instead work more like "see hot lady, get horny" than "need to meet my quota of sexy times for period X".  I think that the whole idea that "I have to go find a partner" is basically either a cultural imperative or a form of addiction.

It's both a cultural and biological imperative, with the former of course being based on the latter. DF does currently work on the "see hot dwarf, get horny" model: All relationships are reactions to (essentially) random stimuli. But in the real world, even individuals secluded in sex-negative communities like prisons, same-sex schools, or abbeys are well-known for having strong sexual urges in the total absence of stimuli.

What is actually wrong with having 3 couples with 30 children each?  Aside from it not being how things presently work, with humans in the real-world.

Well, you were the one with the strongest objection to having inherited names, under the logic that it would invariably lead to pretty much every dwarf in the fort all having the same family name. But in more general terms, having 90% of the breeding being done by just 10% of the (otherwise) successful population is (in my opinion, at least) grotesquely disproportionate, not least in the fact that it does not even remotely follow the laws of survival of the fittest. It's more like "survival of whoever happened to bump into each other the most times over the course of a year."

[Bumber]

What is actually wrong with having 3 couples with 30 children each?  Aside from it not being how things presently work, with humans in the real-world.

Genetic bottleneck. Inbreeding.

[KittyTac]

What is actually wrong with having 3 couples with 30 children each?  Aside from it not being how things presently work, with humans in the real-world.

Genetic bottleneck. Inbreeding.

All not simulated in DF yet. But might be later on.

[Bumber]

What is actually wrong with having 3 couples with 30 children each?  Aside from it not being how things presently work, with humans in the real-world.

Genetic bottleneck. Inbreeding.

All not simulated in DF yet. But might be later on.

Well, they refuse to marry siblings, at least. That cuts down on the available mates, especially taking into account orientation.

[GoblinCookie]

I poked around and, interestingly, was unable to find a clear answer for this. The phrase "to keep the same sexual partner throughout life" is rather vague unless you actually specify whose life. But I'm sure we're agreed that current dwarf behavior is pretty much the most extreme behavior possible. (My favorite is the story of the Miner who threw a tantrum, and fell in love with a dude while literally beating him to death, thus winning herself perhaps the fastest Darwin Award on record.)

Well the dwarf-like situation is pretty much nonexistant in the world, very few monogamous creatures if any will not 'remarry' if their spouse dies.  Those that do are probably in the "will not actually survive without partner" variety.  What is interesting is that there are instances where human cultures have gone through phases of dwarf-fortress like behavior.  The chinese developed this issue at one point, parables about a wife being cut in half by her husbands in the afterlife.  The byzantines also had the same issue as well, one of the emperors got into major trouble with the church because he wanted to remarry a third time because his previous two empresses had not produced any male heirs. 

So it is not unheard of societies to be against remarraige.  It is just the DF world is pretty extreme about this, but it tends to be extremist in general terms at present about nearly everything. 

That's largely correct, I would refine it only as "conditions that make dwarves likely to become friends will, on continuation, also make them likely to become lovers and spouses." As for the starting 7, they also benefit from the double-whammy of arriving at the same time (meaning, they all Eat / Drink / On Break at the same time) and having no other dwarves to socialize with, meaning it's far more likely that the same 2 dwarves will interact, over and over. As time goes on, breaks and mealtimes get far less synchronous, and there are far more other dwarves to get in the way. (And also, social gatherings are no longer restricted to the immediate environs of a wagon.)

The solution to this is for us to have dwarves randomly target particularly people out of their list of acquaintances and make an effort to socially interact with them and to target their existing friends for interaction in the same fashion.  Once everyone has a good number of friends each, then we should not have to worry about the romance part.  We can also bias the friend chance so that people are more likely to target for friendships folks that are of a gender they are attracted to and make the extent this is true dependent upon how horny they are.

It's both a cultural and biological imperative, with the former of course being based on the latter. DF does currently work on the "see hot dwarf, get horny" model: All relationships are reactions to (essentially) random stimuli. But in the real world, even individuals secluded in sex-negative communities like prisons, same-sex schools, or abbeys are well-known for having strong sexual urges in the total absence of stimuli.

In all the institutions you mentioned there are plenty of other people around to provide 'stimulus'.  They do not really therefore provide a very good laboratory to test this claim.  The relevant question however is whether these 'pure' sexual desires (that is not directed towards any real person) actually provide sufficient motive to actually go looking for love in the real-world. 

Well, you were the one with the strongest objection to having inherited names, under the logic that it would invariably lead to pretty much every dwarf in the fort all having the same family name. But in more general terms, having 90% of the breeding being done by just 10% of the (otherwise) successful population is (in my opinion, at least) grotesquely disproportionate, not least in the fact that it does not even remotely follow the laws of survival of the fittest. It's more like "survival of whoever happened to bump into each other the most times over the course of a year."

I think you err badly in confusing the unnatural contraception based reproductive behaviors of modern humans with that of the natural world in the general.  It is pretty much the norm among creatures for a small proportion of the adult population to produce nearly all the babies.  Most creatures produce over 10 babies in one litter, some will actually produce thousands of babies.  Even when you consider the high rate of infant mortality, even if 99% of the babies of a creature that produces a thousand babies die, that means that 10 babies survived, which themselves produce 10 surviving babies. 

Near my dad's house (where I am presently) there is a duck pond.  There are about 50 female ducks I will guess living there and it is now the end of the time of year for ducklings.  There are about 4 seperate mothers with their ducklings and most of the female ducks are clearly ducklingless.  So yes, we are basically talking about only about 10% of the total duck population actually bothering to reproduce.  That works out quite nicely, given that there an average of 10 ducklings in each litter, so when you compare it to the general population of ducks this means we have 0.5 ducklings per adult duck, so in 2 years the whole group has replicated it's entire numbers.  Of course I am ignoring infant mortality here, but the lifespan of a duck is 5-10 years, so even if with a 50% infant mortality rate the ducks will double their numbers in 4 years. 

All this is quite according to the "laws of the survival of the fittest".  That is because those things tend to work at the level of the whole species, or in more widely spread species the race.  A race of creatures that multiplies exponentially is ultimately unfit, because it quickly devours everything there is to eat in it's environment and hence absolutely every creature in that race ends up starving to death. The funny thing here is that the only way for evolution to control the population *is* to make which individuals reproduce completely random, since if it is a trait then natural selection will propagate that trait by operating an individual level. 

So then the "survival of whoever happened to bump into each other the most times over the course of a year.", is pretty much what the survival of fittest propogates.  If it is the survival of the "fittest individual", then before very long every individual will be the 'fittest' and since everybody reproduces the whole race starves to death. 

[GoblinCookie]

Genetic bottleneck. Inbreeding.

Will happen with the current setup regardless. 

[Bumber]

It is pretty much the norm among creatures for a small proportion of the adult population to produce nearly all the babies.

You're ignoring the fact that:

r-selected organisms usually:
   mature rapidly and have an early age of first reproduction
   have a relatively short lifespan
   have a large number of offspring at a time, and few reproductive events, or are semelparous
   have a high mortality rate and a low offspring survival rate
   have minimal parental care/investment

K-selected organisms usually:
   mature more slowly and have a later age of first reproduction
   have a longer lifespan
   have few offspring at a time and more reproductive events spread out over a longer span of time
   have a low mortality rate and a high offspring survival rate
   have high parental investment

Dwarves are K-selected. It doesn't matter what the norm among creatures is.

Genetic bottleneck. Inbreeding.

Will happen with the current setup regardless.

Not with the occasional migrants. More people breeding buys time for new genes to enter. (And the migrants are presumably using the same reproductive strategy as the fort.)

[SixOfSpades]

. . . even individuals secluded in sex-negative communities like prisons, same-sex schools, or abbeys are well-known for having strong sexual urges in the total absence of stimuli.

In all the institutions you mentioned there are plenty of other people around to provide 'stimulus'.  They do not really therefore provide a very good laboratory to test this claim.

True, but it's very difficult to determine whether those other people provide this 'stimulus' directly from pure sexual desire of their own, or merely because they think they're expected to, by peer pressure. Besides, we're never going to find any real GOOD examples of true sexual isolation, because on the large scale, any society that DID practice it would swiftly die out from underpopulation, and on the small scale, hermits living alone in the mountains have no one to document their sexual urges.

The relevant question however is whether these 'pure' sexual desires (that is not directed towards any real person) actually provide sufficient motive to actually go looking for love in the real-world.

Fantasy girls, guys in romance novels, all considerations of "my perfect mate would be", and wet dreams are all divorced from real individuals.

It is pretty much the norm among creatures for a small proportion of the adult population to produce nearly all the babies.

No, it is the norm for a relatively small proportion of adults to produce babies that survive to reproduce themselves. It is the norm in the vast majority of species for every adult to at least try to have offspring, as often as they can without seriously endangering their own survival.

Near my dad's house (where I am presently) there is a duck pond.  There are about 50 female ducks I will guess living there and it is now the end of the time of year for ducklings.  There are about 4 seperate mothers with their ducklings and most of the female ducks are clearly ducklingless.

How many male ducks are there? Many species of ducks form monogamous pair bonds every year, so if the drakes are outnumbered then naturally some of the females would have to go without. And as you say this is the end of duckling season, then other paired females could easily have hatched offspring but already lost them to predation or other causes, or alternatively have found their mates too late in the year to successfully fertilize any eggs.

. . . the only way for evolution to control the population *is* to make which individuals reproduce completely random, since if it is a trait then natural selection will propagate that trait by operating an individual level.

Um, are you sure that's what you meant to say? Evolution is not random selection, evolution is natural selection based on random variation. Now, since in any reasonably large population the distribution curve of "fittest" is usually rather steep (the vast majority of individuals are close to "average", without too many outliers at either extreme), there is indeed a large element of luck in who manages to reproduce & who doesn't, but that's hardly the sole determining factor.

If it is the survival of the "fittest individual", then before very long every individual will be the 'fittest' and since everybody reproduces the whole race starves to death.

No.

[GoblinCookie]

Dwarves are K-selected. It doesn't matter what the norm among creatures is.

Those terms are relative not absolute.  Dwarves are more K-Selected than ducks, which are more K-Selected than fish some of which are more K-Selected than other fish. 

Not with the occasional migrants. More people breeding buys time for new genes to enter. (And the migrants are presumably using the same reproductive strategy as the fort.)

We were originally talking about a theoretical isolated fort.  At present most of the migrants are generated out of thin air, so the problem will not happen regardless of how few of the adults reproduce. 

True, but it's very difficult to determine whether those other people provide this 'stimulus' directly from pure sexual desire of their own, or merely because they think they're expected to, by peer pressure. Besides, we're never going to find any real GOOD examples of true sexual isolation, because on the large scale, any society that DID practice it would swiftly die out from underpopulation, and on the small scale, hermits living alone in the mountains have no one to document their sexual urges.

We really don't need to.  We can basically determine how things work from the fact the majority of adults in most species do not reproduce, even though they physically can. 

Fantasy girls, guys in romance novels, all considerations of "my perfect mate would be", and wet dreams are all divorced from real individuals.

The question is whether those kind of things function basically as a means to increase the number of individuals reproducing in a given society above the natural level for the species, because that propagates the society itself.  It seems to me that there is basically a devil's pact with the population increase that civilization has been running since agriculture was invented.  More people means more surplus value to invest in order to allow the area to support a large population, in an feedback loop that presumably has to end at some point.  Perhaps culture is then basically engaged in driving a greater proportion of it's members to reproduce in order to break the natural balance, in order to drive the feedback loop, but then does this too well and has to control the resulting growth through contraception.

Thing is that as with ducks, the majority of humans cannot have reproduced originally.  That is because if we do use some form of contraception each couple with produce about 12 children.  Even if we kill of 50% of those (has any culture actually had such a high rate of infant mortality) we still end up 6 children each, themselves having 6 surviving children.  So humans cannot have originally been any different from ducks, a few individuals out of the total population reproduced all the babies while the majority did not.  It is only contraception, or a naturally really low birth rate when compared against the reproductive lifespan that ever allows the majority of individuals to reproduce without ultimately causing extinction. 

No, it is the norm for a relatively small proportion of adults to produce babies that survive to reproduce themselves. It is the norm in the vast majority of species for every adult to at least try to have offspring, as often as they can without seriously endangering their own survival.

Where did you get that idea from?  Are you actually talking from experience or are you simply presuming it has to work that way because of your flawed understanding of biology? 

How many male ducks are there? Many species of ducks form monogamous pair bonds every year, so if the drakes are outnumbered then naturally some of the females would have to go without. And as you say this is the end of duckling season, then other paired females could easily have hatched offspring but already lost them to predation or other causes, or alternatively have found their mates too late in the year to successfully fertilize any eggs.

There are roughly equal numbers of male ducks as female ducks.  I assumed that fact would go without saying, since there is nothing in the average duck pond killing off male ducks in particular.  The majority of the female ducks which are ducklingless tend to go around in large groups with the male ducks, the minority of female ducks with their ducklings tend to somewhat keep their distance from the other ducks, male and female alike. 

I have been visiting the same duck pond (it is actually not a pond but rather a stretch of river that passes through a park) for many weeks.  If things were working as you say then I would have seen an initially large number of female ducks with their ducklings at the beginning of spring and all the 'single groups' would consist almost exclusively of drakes.  Then we would see a gradual reduction in the number of mother ducks and the female proportion of the single groups would increase simultaneously. 

Instead what I see is always around 4 mother ducks with their ducklings, but the total number of ducklings per group goes down.  That is to say infant mortality tends to work by reducing the number of ducklings per mother duck but it is not drastically reducing the number of mother ducks.  The ducklings seem to die off individually rather than the whole family being wiped out in one fell swoop.  We start off with 10-12 ducklings and we tend to end up with 4-5 ducklings at the end, implying that the actual infant mortality rate is actually slightly over 50%. 

Um, are you sure that's what you meant to say? Evolution is not random selection, evolution is natural selection based on random variation. Now, since in any reasonably large population the distribution curve of "fittest" is usually rather steep (the vast majority of individuals are close to "average", without too many outliers at either extreme), there is indeed a large element of luck in who manages to reproduce & who doesn't, but that's hardly the sole determining factor.

You seem to have completely misunderstood the type of evolution I was talking about.  Evolution works primarily at the level of the race, or as Charles Darwin put it in the title of the Origin of Species, it is the "preservation of the favoured races in the struggle for life".  It is races that are fit or unfit, not just individuals and it is the fitness or otherwise of races that is the primary concern of evolution. 

The reason for this is not hard to figure out.  The race can survive the death of a large proportion of it's members but if the race perishes then all members of the race will necessarily perish also.  The race can win by sacrificing it's members and their entire family lineages, but the individual family cannot ultimately win by sacrificing the whole race for their propagation, because in the end that means them as well.

If all the female ducks reproduced the whole duck race would become unfit, because such a large number of ducks would eat everything there is to eat in the environment.  Then the whole duck race would starve to death and they would hence all collectively lose the "struggle for life".  Here is the problem, at the level of the individual the female ducks that reproduce are fitter than those that do not, meaning over time whatever traits promote the successful reproduction of female ducks end up becoming uniform. 

This is where the part randomness comes in.  The fitness of the race demands that the total number of female ducks that reproduce be kept at 10%, so that 5 female ducks out of 50 successfully reproduce.  If we decide this according to a specific trait they have, say having red heads, all that happens is that the whole race ends up with red heads.  The next generation then (it is that fast) all have red heads and hence 100% of the females reproduce and everybody ends up starving to death. 

The trick is to (at a racial level) select to make reproductive success totally random, but fix the odds at the level that ensure that a manageable number of surviving offspring are produced.  Since luck is not hereditary, there is no way for the lucky female duck to pass on the fact that she was the lucky duck that got to breed to her daughters is there?

[Cathar]

Okay so both of you are wrong and I urge you to read the book before having this kind of argument. Dawkins made an excellent audiobook available on youtube that vulgarizes the whole "evolution by means of natural selection" thingy.

The basic idea behind this is every animal within the specy carries with him a number of traits which statistically affect the number of offspring they will have before dying. Over multiple generations, those traits will multiply over the population as they produce more "competitively" fit individuals. Exemple : you have a population of ducks. 25% of male ducks have a green head. Green head ducks produce statistically 1.25% more offsprings before dying than brown head ducks. Over the course of multiple generations, the cumulative reproductive success of the green head ducks will be such that green head male ducks will become the norm.

Whether the trait helps the individual to survive until he can reproduce, help him to reproduce faster or over a longer period, or attract more mates is irrelevant.

> But if they all reproduce they will eat all the ressources !!

They don't exist in a vacuum. Ducks have predators, they are themselves a ressource. If ducks overbreed, some ducks will bear a trait of being statistically smaller to consume less ressources and that will become a beneficial trait for the individual that will quickly spread to the collective by means explained above

[GoblinCookie]

Okay so both of you are wrong and I urge you to read the book before having this kind of argument. Dawkins made an excellent audiobook available on youtube that vulgarizes the whole "evolution by means of natural selection" thingy.

The basic idea behind this is every animal within the specy carries with him a number of traits which statistically affect the number of offspring they will have before dying. Over multiple generations, those traits will multiply over the population as they produce more "competitively" fit individuals. Exemple : you have a population of ducks. 25% of male ducks have a green head. Green head ducks produce statistically 1.25% more offsprings before dying than brown head ducks. Over the course of multiple generations, the cumulative reproductive success of the green head ducks will be such that green head male ducks will become the norm.

Whether the trait helps the individual to survive until he can reproduce, help him to reproduce faster or over a longer period, or attract more mates is irrelevant.

I already said most of that.  This is why there is not the kind of variations of fitness in the population that Six of Spades thinks there is, in mere centuries the accumulated advantages of even a small advantage adds up to 100% and we are talking thousands or millions of years.  The genetic fitness of individuals tend to be level, which is why the fitness of the race tends to be the primary issue. 

They don't exist in a vacuum. Ducks have predators, they are themselves a ressource. If ducks overbreed, some ducks will bear a trait of being statistically smaller to consume less ressources and that will become a beneficial trait for the individual that will quickly spread to the collective by means explained above

All the ducks starved to death.  They are not going anywhere, as even the smaller ducks are not smaller enough to survive in the conditions they created by all reproducing the half-dozen babies they are capable of raising to adulthood given their general rate of infant mortality. 

If there is twice as many people as there is food, then if I need 20% less food does not mean I am any less dead. 

[Cathar]

I already said most of that.  This is why there is not the kind of variations of fitness in the population that Six of Spades thinks there is, in mere centuries the accumulated advantages of even a small advantage adds up to 100% and we are talking thousands or millions of years.  The genetic fitness of individuals tend to be level, which is why the fitness of the race tends to be the primary issue. 

The fitness of the race. What is that ? I'm genuinly puzzled. Natural selection doesn't deal with races, it deals with genes.

All the ducks starved to death.  They are not going anywhere, as even the smaller ducks are not smaller enough to survive in the conditions they created by all reproducing the half-dozen babies they are capable of raising to adulthood given their general rate of infant mortality. 

Tho local extinctions do exist, I can still find ducks if I take a walk in the forest and I live very far from that pond. I fail to see how this is relevant

If there is twice as many people as there is food, then if I need 20% less food does not mean I am any less dead.

Depends. If a 20% smaller size give you, let's say, a 0.5% increase in your survival rate, it will translate into more reproductive success and your gene will spread faster than the other genes in the pool.

But yeah if you drop an atomic bomb that kills everything natural selection is irrelevant ok