"Every group and organization is an open system that exists in multiple environments. Changes in the environment will produce stresses and strains inside the group,forcing new learning and adaptation. At the same time, new members coming into the group will bring in new beliefs and assumptions that will influence currently held assumptions. To some degree, then, there is constant pressure on any given culture to evolve and grow. But just as individuals do not easily give up the elements of their identity or their defense mechanisms, so groups do not easily give up some of their basic underlying assumptions merely because external events or new members disconfirm them."
Schein, E. H. (1990). Organizational culture. American psychologist, 45(2), 109.