  We have investigated the essential ingredients allowing a system to show Self
Organized Criticality (SOC) in its collective behavior. Using the Bak-Sneppen
model of biological evolution as our paradigm, we show that the random
microscopic rules of update can be effectively substituted with a chaotic map
without changing the universality class. Using periodic maps SOC is preserved,
but in a different universality class, as long as the spectrum of frequencies
is broad enough.
