Demographics - How population grows.

[Jalyha]

Wow, you guys really seem to have a grip on this topic already!!

During much of human history, birth rate was about the same as death. Population did not increased and if it does increase you might have a problem. Unless there is a new technology or something that allows to grow more food on the same space you will end up unable to feed everyone. Less food meens that you might only have have a lower life quality that will reduce birth rate or increase death rate. Or you could have up to 10% of the people die of starvation in 3 years only, like in the 14th centuy.

Another reason why population was not increasing is because of frequent desease and famine. These two where pretty frequent and killed millions of people. Even in the 20th century and today in some poor countries.

War is also a major cause of death. The Taiping rebelion in China is probably the dedliest conflict in human history. It was a civil war and there where other conflicts in the region at the same time !!! if I remember correctly. I guess that's what happends when you loose the mandate of heaven... Not only people die on the battlefield but lands/ villages get burned, many civilians are massacred, and these is still famine and desease because of crops got burned or have rotten in the soil since everybody is busy elsewhere. That is what is going to happend in Game of Thrones...

Which is why population growth isn't stable. If you follow the *projected* growth at our current average rate, we *should* already have over 700 billion people on Earth, instead of 7 billion. Thank goodness earlier generations were more in control! (With or without birth control ) And wars have decimated entire populations for centuries! While I don't believe war is ever a good thing (in the real world) it does tend to keep the population from spreading too rampantly.

On the population per food thing, though.. you do have to be careful not to be too rigid with it. Populations DID grow, they simply grew extremely slowly. Babies are born. It just happens. And not all societies saw population exceeding food sources as a bad thing. Consider more recent/well known *tribal* societies' behaviors and it's easier to understand how things may or may not have worked.... Many tribal people would marry their children off to other tribes. Part of the decision to begin that practice was surely a practical one. And when food sources get low, groups of people would go out looking for new food sources, and either split from, or move the tribe to the new source.

And yet, the birth rates for those societies (the ones that do still exist in modern times) is often higher than the birth rates in most countries, (then again, so is the crude death rate), so you do still have a narrower growth rate. It's absurdly hard to measure, though. Different organizations try and come up with different results... Consider these Birth Rate lists.

I digress... Also I would laugh so hard if *everyone* died due to crop losses in GoT!

See also Dragon Magazine #89 "Survival is a group effort" ( http://annarchive.com/files/Drmg089.pdf is a copy that may or may not be legal) for a good discussion of the basic population growth rate equation and a discussion of the two factors (females per female per generation and generation time) might impact how a world works with different races having different generation times.

What a great resource!! Thank you! Most people tend to overdo their gender/population ratios in one way or another when writing about human races, but it's possible to have VERY dramatic differences with other races!

And life expectancy is a HUGE factor!

On the topic of birth control I want to mention that birth control was well known right back to the ancient period, it was just a lot less reliable back then - but it did very much exist. It is a big thing though and when designing a world is worth considering.

A very valid point. Related strongly to world-building, as well, since birth control methods/knowledge might exist (or not exist) differently on certain worlds. (Perhaps the only way to end a pregnancy on planet X is by visiting a witch doctor who charges 10 years of your life! I wonder how that would affect your population?!)

The ancient Mediterranean peoples were reported to use an herb known as Silphium that, among other properties, was a highly effective abortifacient. High demand for the herb drove it to extinction in emperor Nero's time, according to reports.

A world with functional magic would have ramifications for population dynamics, especially if the practice of said magic is sufficiently taxing that reproducing female wizards are a near-impossibility. Similarly, the major causes of death in childbirth could be probably reduced to near-zero with a practicing priest in the community (something as simple as D&D's Cure Light Wounds should be sufficient to prevent most of the childbirth-related mortaility, even without more specialized magics aimed at reproduction). Overall, it's not a topic that's discussed much because it doesn't have any significant impact in game terms, but has a HUGE impact in worldbuilding terms. And Americans have traditionally displayed a peculiar aversion to their pimply-faced youths discussing anything to do with sex.

That would certainly slow childbirth related mortality!! But without proper *knowledge* of the workings of a human body, they may still miss many of the problems that lead to miscarriages, or pre-term births! And would a spell that cures wounds work on a not-yet fully developed heart or brain or lungs?

And yeah, I was hesitant to post the topic because it's usually taboo.... but it *does* affect population growth, which has a huge impact on world building ... (doubly so in regards to books as opposed to game development.)

[waldronate]

Demographic-economic paradox - Wikipedia, the free encyclopedia is an interesting graph showing number of offspring per woman against gross domestic product.

And on the reproductive magic front, a sufficiently advanced magic would most likely allow for selection of healthy offspring characteristics, number of offspring per birth, and so on. It would also potentially allow for the development of external non-human uterine replicators to allow for potentially unlimited numbers of offspring for a sufficiently adept or rich individual. Even application of magic to the two basic limiters in a population (food and hygiene) would make a huge difference in how the world develops (the longer unrestrained breeding can occur, the longer the population rides that J-curve).

In my opinion, the critical long-term drivers for the success of a culture are:
1) an increasing population (the number of geniuses per capita seems to be very roughly constant),
2) sufficient surplus in the culture to allow for specialization (if everyone is a subsistence farmer, you're not going to develop too much knowledge on any one subject),
3) a way and will to broadcast persistent information (writing + printing press to let everyone know about that neat stuff that your specialists have discovered).