To get a better understanding of the author's experience with a topic, or how there views have evolved, you should review what else they have produced. For academic researchers this may be looking at their previous articles or even previous books (or book chapters). Some departments or disciplines prefer one format or another, but the following tools should help you find their work.
Depending on the author, it might be useful to look for non-academic sources to find additional content that the author has create related to your book's topic. You might find interviews (print, video, or audio) where the author talks about their research or their point of view related to the book. Plus, you might be able to document the development of the author's ideas through time.
Along with a Google search for the author's name, look specifically for their personal websites, the book publisher's website for the book, or even their Twitter account. You may also want to look for their work in professional organizations: have they chaired certain committees, or served as guest speaker for workshops or events? All of this work helps inform their points of view and experience with a topic.