There are several age categories:
* very young
* young
* mature
* middle-aged
* old
* very old
* ancient
* very ancient
* eternal

The younger you are, the lower your mental stats, but your physical stats
tend to be higher. As you progress in age, there is a gradual shift away
from physical stats to mental stats, specifically Wisdom.  Ancient beings
tend to be very wise but very frail. Age is indicated in your score.  There
are a few spells which can cause aging, and which can reverse aging
effects. Eternal beings neither benefit from old age nor suffer from it. 
They also do not start out as naieve as other races and thus suffer no
penalties nor receive any bonuses from age.