Beastmen or Lycanthropes are humanoid monsters that can transform into their respective animals/creatures/beasts. The life span of lycanthropes is not much different than that of humans. The only difference being their longer youth, lasting from 30~50 years. In fact, when they start to grow old, their bodies began to quickly weaken and they tend to die within two weeks. However, when they become a Devil (Majin), their lifespans increase several folds. An example would be the devil Grucius who has been a Majin for around a hundred years, meaning he's actually 'lived' for a longer time.
The Beastmen, are a race that thrives in battle. Strong enemies are something that they welcomed.