After more than 40 years of life, software evolution should be considered as a mature field. However, despite
such a long history, many research questions still remain open, and controversial studies about the validity
of the laws of software evolution are common. During the first part of these 40 years the laws themselves
evolved to adapt to changes in both the research and the software industry environments. This process
of adaption to new paradigms, standards, and practices stopped about 15 years ago, when the laws were
revised for the last time. However, most controversial studies have been raised during this latter period.
Based on a systematic and comprehensive literature review, in this paper we describe how and when the
laws, and the software evolution field, evolved. We also address the current state of affairs about the validity
of the laws, how they are perceived by the research community, and the developments and challenges that
are likely to occur in the coming years