לזכות אהובי ר' יעקב דב בן דוד הכהן
Man is born a WILD donkey.
Then he evolves into a human being.
Sometimes - he remains a wild animal that looks tame in order to be socially accepted and presentable but inside he remains the way he was born.
A WILD donkey.
In order to make this evolution happen hard work is necessary. It requires a constant polishing of one's character through study and practice of overcoming temptation and instinctual desires.
This "theory" is actually found in a pasuk:
עיר פרא אדם יולד" - איוב י"א י"ב"
[Based on the Alter of Kelm]