Thanks.

If you plan on getting a lot of cities, try Altar and do a LOT of quests.  +1 prestige per quest means that, without really trying too hard, you get about 30 prestige by midgame.  I'm playing a game with them right now where I have over 40 prestige between my sov, research, and all the quest prestige. 

Food does not affect growth, but it limits the max population. 

If you have two cities and 6 prestige they will grow with 3 population each. If one has hit maximum population then one city grows with 3 (still) and the other will grow nothing until you get more food.

Thanks.  The Hiergamenon, needs a lot of work.

Before the buildings that gives a set bonus, the population growth works like.. as far as I know, like this:

You take your Prestige (located at the top of the map), and divide out on all your cities, (2 prestige out to 3 cities gives 0.66 population per turn in each city, 6 prestige on 3 cities gives 2 population per turn in each city). Prestige can be gained by techs, buildings and leveling your sovereign.

Food dictates your maximum amount of population in your city, say you build your first city on a 4 grain spot, the starting food per grain is 20, so you will have 4 times 20 as food, for 80 available maximum population, you can see the food available if you click on a city, and click on the details button bottom left.
Of course food changes when researching certrain civic techs, and building certain buildings.

PS. the Hierga-nom-nom doesn't work in my experience I would try other places for my information

Sincerely
~ Kongdej