What do historians learn from skeletons?

is that which studies human skeletal remains in order to reconstruct the past, understand human variation, and provide information about the deceased individuals, such as their age at death, sex, ancestry, stature, pathological conditions or traumatic injuries; the remains from medico-legal or police cases fall under the branch offorensic anthropology.

Well u can determine age or sex or how peoples life styles were like back then

Sasuke was obssed by naruto being powerful so he wants to be more powerful. and at killed hi own brother and became rouge ninja