Most of the interpretation on these graphs seems like subjective speculation. One thing I think is worth pointing out is that the observation that "C, C++ and

Most of the interpretation on these graphs seems like subjective speculation. One thing I think is worth pointing out is that the observation that "C, C++ and Perl projects are significantly more "top-heavy" than those in other languages, with a smaller core of contributors doing more of the work" may be almost entirely explained by the fact that projects in those languages also have a larger median number of contributors. If you postulate that the size of the core group of committers is the same for all languages and projects (in my experience, this number is very close to 1), then projects which attract more occasional contributors will appear more "top-heavy" because the core is a smaller fraction of the total population of contributors.