A selectionist approach to human ontogenetic development relies on three ba
sic processes: variation, selection, and retention. The approach further im
plies chat for adaptive behavior to emerge during development, each of thes
e processes is required. Nevertheless, to date variation has been relativel
y neglected. Some studies show that behavioral variability is enhanced when
the appropriate contingencies are present. Moreover, behavioral variabilit
y has been shown to facilitate the acquisition of difficult behaviors in an
imals (e.g., Neuringer, 1993). In the first part of the present paper, we b
riefly recapitulate the basic tenets of selectionist psychology and attempt
to explore the role of behavioral variability in human behavior. In the se
cond pare, its importance in the emergence of intelligence, humor productio
n, and self-regulation is discussed. We present data suggesting that variab
ility enhances intelligent behavior, qualitative humor production and effec
tive self-regulation.