In zoos the wolf can live to be up to 16 years old. In the wild it can be up to 13 years or maybe more. But the wolf usually lives to be to 8 and then it dies. The record wolf lifespan is about 20 years of age.
The reason the wolf dies at eight is probably because life is really hard in the wild. Another reason might be because of all the poison in its blood from the food it eats or from traps and the wounds it gets from them.
In captivity the wolf gets to be older because they are safe from the outside dangers of traps, snares, enemies and poisons.
