This is an academic book aimed at other academics. I believe I purchased it 20 years ago when it was newly published (2000) and I was considering writing an undergraduate thesis on this topic or even in pursuing graduate studies on the topic, neither of which I never did. In fact, I managed to carry this book around for 20 years without reading it until now.
The format is thus: An academic writes a "principal paper"; a bunch of other academics respond with "commentary discussion"; the original author responds to the criticism. This happens four times. The first two topics are based on research into other primates; the third and fourth focus on humans. It really is about the behavioral nuts and bolts of exactly how morality evolves. I suppose I was most interested in Christopher Boehm's "Conflict and the Evolution of Social Control," which maintains that humans are (courtesy our evolutionary heritage) inherently "despotic" and so we must make a conscious effort toward "egalitarian" living or else we will default to alpha-male chauvinism.
I think this book, despite being "cross-disciplinary" (as per the book's subtitle), is mostly helpful to a small academic community that wants to peer-coach itself in improving its own research hypotheses. There isn't a takeaway for readers who aren't already tackling this professionally. But if you are doing it as a career, it goes into depth and might be useful.