Demographics

[Chopper]

Trying to understand the relevance of life expectancy? Is this something that should be taken note of?

[CerberusIV]

It's based on the healthiness of your cities (like approval rating is based on happiness). I don't find it particularly useful, it's more important to keep an eye on the individual cities to deal with unhealthiness and unhappiness issues.

[Addled Platypus]

try killing off a bunch of your own units in a war, watch the results with unhappiness

[Diadem]

Yeah they are rather useless statistics, life expectancy and approval rating. The former is related to health, the latter to happiness. I don't know how they work exactly, but for example building globe theatre in an OCC game gives you 100% approval rate

To illustrate their meaninglessness: Whipping your population to death increases both your life expectancy and approval rating.

[Blake]

Approval Rate is (Happy / (Happy + Unhappy)), a city is happy at 50% or higher, the same calculation is used for life expectancy. Having much higher happy than unhappy means your cities can grow more.
So as such your target should be just over 50% for approval rate (you want your cities as large as possible), and just under 50% for life expectancy (it's okay to be a little unhealthy), altough in some cases you have a great abundance of happy or health.

Because the calculation is so dumb there are interesting results like whipping always increasing both life expectancy and approval rating (maybe that is true of the survivors) and even more amusing that drafting always improves life expectancy.