OK, here's something odd.
Rome in 875BC (roughly my first contact)
Rome in 490BC:
And Rome in 10BC:
I note the following:
City----------------875BC-------490BC-------10BC
Antium--------------3-----------------3-------------4
Cumae--------------3-----------------2-------------5
Hispalis-------------3-----------------2-------------6
Lutetia--------------3-----------------3-------------5
Neapolis------------4-----------------4-------------6
Pisae----------------2-----------------4-------------6
Pompeii-------------3-----------------3-------------4
Ravenna------------2-----------------1-------------4
Rome----------------5-----------------4-------------5
Veii-------------------4-----------------5-------------7
Vironconium--------2-----------------4-------------6
TOTAL POP--------34----------------35-----------58
Something odd is going on. Between 875BC and 490BC there should have been 17 turns by my reckoning. Rome, for example, has 5 improved grassland squares it can work, so there's no reason it shouldn't be at +2 fpt. Yet it loses a population point, rather than gaining a couple. An 875BC city investigation shows Rome was working those 5 tiles, with +2fpt. Furthermore they had 3 luxuries, so they had 3 happy and 2 content people. Where, I wonder, did the population go?
I would suggest that of the 11 cities, only Pompeii and Lutetia should be at less than +2fpt, and perhaps Pisae, depending on how the AI split tiles with Rome. If one makes allowance for the bonus foods present (two cows, for instance) then an average of +2fpt per city is reasonable. Rome should have generated +22fpt overall, which for towns should average to just over one population growth per turn. Yet instead of growing by 17 (875BC-490BC), the total population grew only by one! I don't believe they made 16 workers, surely.
Between 490BC and 10BC the population grew by 23 - almost exactly the predicted 1 per turn (24 turns) - and there is little or no irrigated grasslands, so I don't think that explains the delta.
What I'm wondering is...was the AI trying to build 'banned' units, and then losing the population somehow? Or is this just indicative of the AIs dreadful population/food balancing skills.