  A major obstacle in analyzing the evolution of information exchange and
processing is our insufficient understanding of the underlying signaling and
decision-making biological mechanisms. For instance, it is unclear why are
humans unique in developing such extensive communication abilities. To treat
this problem, a method based on the mutual information approach is developed
that evaluates the information content of communication between interacting
individuals through correlations of their behavior patterns (rather than
calculating the information load of exchanged discrete signals, e.g. Shannon
entropy). It predicts that correlated interactions of the indirect reciprocity
type together with affective behavior and selection rules changing with time
are necessary conditions for the emergence of significant information exchange.
Population size variations accelerate this development. These results are
supported by evidence of demographic bottlenecks, distinguishing human from
other species' (e.g. apes) evolution line. They indicate as well new pathways
for evolution of information based phenomena, such as intelligence and
complexity.
