An undeniable factor for an open source software (OSS) project success is a vital community built around it. An OSS community not only needs to be established, but also to be persisted. This is not guaranteed considering the voluntary nature of participation in OSS. The dynamic analysis of the OSS community evolution can be used to extract indicators to rate the current stability of a community and to predict its future development. Despite the great amount of studies on mining project communication and development repositories, the evolution of OSS communities is rarely addressed. This paper presents an approach to analyze the OSS community history. We combine adapted demography measures to study community aging and social analysis to investigate the dynamics of community structures. The approach is applied to the communication and development history of three bioinformatics OSS communities over eleven years. First, in all three projects a survival rate pattern is identified. This finding allows us to define the minimal number of newcomers required for the further positive community growth. Second, dynamic social analysis shows that the node betweenness in combination with the network diameter can be used as an indicator for significant changes in the community core and the quality of community recovery after these modifications.