Why do scientists write, and share scientific software? Writing and sharing scientific software is a means to communicate scientific ideas for finding scientific concensus, no more and no less than writing and sharing scientific papers is. Important factors for successful communication are agreeing on an open source license, technological solutions to sharing development, using a language that is understood by many, a system of peer review that fosters evolution and diversity, and sufficient possibility for contributors to be recognized as individual, and awarded. This talk will discuss all these items mostly in the light of the ecosystem of R, a free software environment for statistical computing and graphics, which is largely driven by academics.