OK, this was brought up in a thread in the general forum:
Anyways, the idea here is that it's possible to make different graphics for the units in each of the different eras, like the worker changes in the industrial and the leader changes from era to era. So, to make the game look a little better - for example, adding spearman graphics for different ages (like a militiaman or a guerrilla) to at least make the tank v. spearman incident appear to be more acceptable, lets start coming up with ideas and making graphics that can be used for modernizing obsolete unit graphics.
Anyways, the idea here is that it's possible to make different graphics for the units in each of the different eras, like the worker changes in the industrial and the leader changes from era to era. So, to make the game look a little better - for example, adding spearman graphics for different ages (like a militiaman or a guerrilla) to at least make the tank v. spearman incident appear to be more acceptable, lets start coming up with ideas and making graphics that can be used for modernizing obsolete unit graphics.