Previous studies have indicated that complex symbolic communication systems are shown to evolve through both the processes of horizontal transmission and vertical transmission. Here we explicitly compare the emergence and evolution of graphical signs in these two transmission processes through the use of two different microsociety organizations. In Experiment 1 participants engaged in a graphical communication task either as a member of a fixed closed-group community or as a member of a replacement chain, where the population structures were continuously changed so that the most experienced members were replaced by naïve participants after each round. This study compares the two models and their emergent signs across three measures of sign complexity (Perimetric Complexity, file length, and number of lines drawn). In both conditions effective sign communications arose and signs within both microsocieties rapidly simplified. Experiment 2 used the output from the earlier microsocieties to assess whether chain-final signs proved to be incomprehensible to naïve individuals, through an online naïve judgment task. The results of the experiment suggest that while both conditions showed the loss of sign complexity over the course of the rounds, neither condition showed faster nor more significant decreases in sign complexity. Moreover, the results from Experiment 2 also showed that the majority of the resulting images retained high amounts of iconicity so that naïve learners not involved in the process of sign negotiation were accurately able to identify the correct referent for most drawings.