The alula is a small structure that is found on birds. It is located at the joint between the hand wing and the arm wings of birds and it is the freely moving, first digit of a bird's wing. It is normally used by birds in slow flight. In humans, the structure that is comparable to the alula is the thumb.
The Big Five trait dimension or the five factor model is based on descriptors of personality. The big five traits are:
Openness
Beuroticism
Agreeableness
Extraversion
Conscientiousness
From these, the trait expressed is Extraversion. This trait is characterized by outgoing and energetic behavior. Energy creation is gained through external means.