Thank you all for your feedback. When I was researching data for this project a few days ago, I mainly used this wikipedia article for estimating the population:
en.wikipedia.org
.
I took careful note on the fact that the New England colonies had incredibly high birth rates and, when coupled with relatively low mortality rates, resulted in a high population growth there. I concluded that if a Roman "colony" managed to improve the quality of life for all people within their borders (except for native slaves), and if they encouraged pro-natalist policies to get their birth rates up, I could sort of imitate this effect so that I don't end up with a severely depopulated country with a native supermajority.
OK, first off, I'm not sure that using the growth rate of New England colonies is a good idea. These colonies were established well over 1,000 years after your POD. It would make much more sense to have a look at the demographics and growth rates of other civilisations that were extant in 400 A.D. Applying growth rates from 1600 to 400 A.D. is anachronistic and doesn't make sense when you can look at the growth rates of the Roman Empire, which would obviously be the best example.
When I was researching, I also encountered the problem that there would not be a constant supply of new settlers to fill up the colony. According to the article, however:
"All the colonies grew mostly by natural growth, with foreign born populations rarely exceeding 10%. The last significant colonies to be settled mainly by immigrants were Pennsylvania in the early 18th century and Georgia and the Borderlands in the late 18th century, as internal migration (not immigration) continued to provide nearly all the settlers for each new colony or state."
So basically, I figured that I would be able to replicate the population growth of the English colonies from 1607 to 1776. I could not find any good sources of maps showing the expansion of colonies over time, though, so I made the inference that the English started at the coast and slowly made their way to the Appalachians. In this case, they start at Virginia Beach and slowly make their way North and South along the coast.
Here's another quote about the population growth:
"The regional economy grew rapidly in the 17th century, thanks to heavy immigration, high birth rates, low death rates, and an abundance of inexpensive farmland. The population grew from 3,000 in 1630 to 14,000 in 1640, 33,000 in 1660, 68,000 in 1680, and 91,000 in 1700.
Between 1630 and 1643, about 20,000 Puritans arrived, settling mostly near Boston; after 1643,
fewer than 50 immigrants arrived per year. The average size of a family 1660-1700 was 7.1 children;
the birth rate was 49 babies per year per thousand people, and the death rate was about 22 deaths per year per thousand people. About 27 percent of the population was composed of men between 16 and 60 years old." (
https://en.wikipedia.org/wiki/History_of_New_England)
Bolding mine.
So in New England we have 20,000 Puritans arrive in 13 years. This is almost twice the number of your original population. You then have the population being topped up by immigration amounting to the total birth rate of 1,000 people per year. This is not including the death rate. We know how exponential growth works thanks to Covid, so that should give you an idea of how it works in terms of demographics; just that small number of immigrants - which your colony does not have - would have a dramatic effect over the course of 100 years.
Additionally - and I'm not a mathematician so if there's one in the house correct me if I'm wrong - but if you have a Roman growth rate of 0.1% then 12,000 people should grow to 12,012 people in one year. However, if you also have foreign born populations exceeding 10% then that 12,000 becomes 12,120 in a year. So 10% foreign born populations might not seem like lots, but it's huge.
Next, we should consider and compare life expectancy and family size between Romans and New Englanders.
"The average life expectancy in Ancient Rome at birth was 27 years old. Early deaths in women were common because of the dangers of childbirth and men often died on the battlefield." (
https://en.wikipedia.org/wiki/Family_in_ancient_Rome)
"Average life expectancy at birth for English people in the late 16th and early 17th centuries was just under 40 – 39.7 years. However, this low figure was mostly due to the high rate of infant and child mortality; over 12% of all children born would die in their first year.A man or woman who reached the age of 30 could expect to live to 59. Life expectancy in New England was much higher, where the average man lived to his mid-sixties and women lived on average to 62." (
https://www.plimoth.org/sites/default/files/media/pdf/edmaterials_demographics.pdf)
Romans, on average, lived 13 years less than New Englanders. This is significant because it means less time for woman to be giving birth. Additionally, as you see in the first quote, the more babies you make your Roman woman have, the more likely they are to die. Clearly this has implications for the growth rate of your settlement.
Next, we should consider the average number of children Romans and New Englanders had:
"Most Roman families had a lot of children, because so many of the kids
died young. The average Roman family had five or six kids, but only two or three of them lived to grow up."(
https://quatr.us/romans/roman-families-children-households-ancient-rome.htm)
"An English woman who married at the average age of 23 1⁄2 could expect a reproductive span of about 20 years. In New England, where women typically married at 20 or 21, the potential years for giving birth increased by those two or three years.The typical English woman would give birth six or seven times.The average number of children born to a New England couple was slightly over eight. While this difference is not striking, the difference lay in the number of children who survived to adulthood. In 17th-century England, the average household size was 4.75 persons. In New England, an average of 7-8 children reached 21." (
https://www.plimoth.org/sites/default/files/media/pdf/edmaterials_demographics.pdf)
The difference here is striking. On average, more than twice as many New England children made it to adulthood than did Roman children. You cannot just apply New England growth rates to a Roman colony and the results be in any way realistic.
Unless of course you don't mind about realism and just want to achieve whatever your predetermined end point is.
So, I first went to thinking how it would be possible for me to get birth rates high. I envisioned an entirely new society being created, so there were a lot of different things that I could try. First off, I made sure to include that basically every fruit, grain, nut, berry, domesticated animal, and vegetable known to the Romans was brought over in their admittedly oversized fleet. In this way, the people would have a more varied diet and, when combined with the three sister crops that the Americo-Romans will eventually get from the blossoming Mississippian civilization, they would probably be VERY well-fed. I even added the part about that one fellow bringing along the honeybees... my idea there was that that hive could be multiplied later on so that we can have bees pollinating orchards and crops to even further increase crop yields.
Bolding mine.
I think it would be much more realistic and a more enjoyable TL to explore how things would happen 'IRL' rather than making everything go according to 'plan' a la a Civ 6 game.
Of course, it's your TL so if you want to handwavium a Roman utopia* stretching from sea to shining sea where everything goes absolutely perfect and every person is impervious to disease and has an additional few decades on their expected lifespan then that's fine. You shouldn't just apply a 1600 situation to a 400 A.D. situation though.
*utopia for the free men, obviously, as the women are spending approximately half their 'adult' lives pregnant (i.e. first period at 14 years old, eight children meaning six years pregnant, and then dying on average age 27 - welcome to America, ladies). It also doesn't sound so good for the Native American chattel slaves. The ones that are defeated, captured, and enslaved without the Romans losing too many men - if any - in battle, because that might ruin the growth rate.
I also made sure to give the Americo-Romans a larger starting population - about 12,000 people - so that I wouldn't have to slowly work my way up into the thousands from just a few hundred people. I tried to create a society without a nobility, one with engrained core values of a free market, social mobility, and equality for all Roman men. I didn't want some sort of a plebeian class re-emerging, so I made sure to add the presence of a slavery system reminiscent to what we saw in the U.S. before the Civil War. And since literally everyone in the colony is there because of either intelligence or because they excel in a certain trade, I envisioned the colony prospering and making societal leaps so that we could see things like a Pony Express-type system and a public school system. I don't plan to have this timeline be one where the Imperium just expands endlessly until they have everything from Alaska to Venezuela, though. In the year 566 I plan to halt their expansion completely at OTL Proclamation of 1763 borders for reasons I will give later on.
I think that for everything you do, you need to ask "why?" You need to put yourself in the shoes of your Romans. Why don't they want a nobility? Who has come up with that idea? How does that person convince everyone else of it? Are they brainwashed? Do they use some kind of democratic system? You said not? Why do they need a pony express? How does the idea of having all Romans as equal but having the Native Americans as slaves work? What's the Native American response to this? They're not all that technologically inferior so why don't they fight back? If they do fight back, how many Romans are lost? Why is there a public school system? Why do the settlers need to be educated when surely a lot of their effort is going into food production? What are they being educated in? Why, instead, aren't the children being trained in warfare a la Sparta given that there are constant wars with the much more populous natives? Etc, etc.
There are lots of questions that if answered would make the TL much more interesting and feasible.
Like the title states, this is just a brainstorm. If any of you have better statistics or ideas to make the timeline more interesting or more feasible, feel free to post edited versions of the excerpts I post or post excerpts of your own. I'm fairly new here, and I wanted to make a thread like this before making an actual timeline. This way, I can get constructive criticism so that I can improve the timeline. Once again, I really appreciate you guys' feedback.
I think that to start with you should think about your initial population.
How many men are there? How many are soldiers? How many are farmers? How many are quarrymen? How many fishermen and blacksmiths?
How many women are they? What is their role? Literally just having children? What were women actually doing in the Roman Empire at this time?
What about children? How many children are there?
What are the ages of the Roman settlers? Who is young enough to be at these public schools and who is old enough to be sent to work/war? Who is too old to procreate or contribute much? What do the farmers and soldiers think about the musicians, poets and writers who seem to be sat about all day whilst they spend all day in the fields either farming or fighting?
How many shields and swords do they take? Once they get damaged how do they find more? Do they get lucky and stumble across the metal deposits needed to make more? The same with stone quarries to build stone buildings - how long does it take to find a suitable place to quarry, set up the quarry, mine the stone, and build the buildings? Would wooden houses do for the time being? Do they have enough saws, etc?
There's a Hell of a lot to think about to make this TL realistic. However, that being said... it doesn't need to be realistic if you don't want it to be. You should state that though.
Northstar