Talk at SOS-Evol 2013. The Linux kernel git repository hosts several years of activity. We have analyzed it with the aim to learn about the "age" structure of the community of developers, and how it has evolved over time. After looking at the commit activity by each of them, periods of stay and leave have been determined, and later used to draw demographics pyramids, with time of stay in the project as "age". The analysis of such pyramids and related parameters help to better understand the experience of the community of developers, how new people is entering the project, and some bounds on the future evolution. We propose this analysis on the Linux kernel as a case study of a methodology that could be used to study many other development communities.