In the glassy state, the molecular relaxation process is a cooperative phenomenon
and one structural unit is allowed to move only if a certain number of neighboring structural units are engaged in the same process (7).
Sexual reproduction, one of the major outstanding puzzles in evolutionary theory, is also a cooperative phenomenon
, as the term is used here.
Of particular interest to us is the appearance of 1/f noise, which provides a clear indication of some sort of collective effect, or cooperative phenomenon
, present in the process that generates the signal (22).