Reference #445: Organizational Culture and Leadership
Animals have a clearly defined flight distance and critical distance. When intruded upon at these distances, an animal will respectively flee or display aggressive behaviour.
While not to the same extent as non-human species, crowding will elicit aggression in humans. Hence most cultures have fairly clear rules on how to define personal space, and to respect it.
Schein. Organizational Culture and Leadership, 2017. (93)