Darwin's Watch: The Science of Discworld III by Terry Pratchett

Although a little more scattered in content that the previous two volumes, the third installation of The Science of Discworld doesn't disappoint. Focusing on Charles Darwin and his contribution to our understanding of evolution, the book tosses in a little extra, covering things like time travel and analyzing the Victorian Era's contribution to thinking. Among the facts, as always, there's the entertaining tangent into Discworld where external interference makes Darwin write the wrong book and everything goes haywire.

We join the faculty of Unseen University once again who, with the help of their amazing machine, Hex, untangle the web of events that lead to Darwin mistakenly writing Theology of the Species instead of Origin of the Species. This alternative book is all about divine design, and veers just far enough off the proper path of time to have far-reaching effects. This "wrong" book delays scientific advancement, which ultimately leads to the end of the human race. Through carefully calculated interventions in time, and one eye-opening oops, the wizards attempt to get Darwin back on the right track.

Between the chapters on the progress of this all-important mission, detailed commentary covers topics related to physics, time travel, evolution, and more. Can altering one tiny event make a significant impact on history for real? Will time travel ever be more than a theory? It's all very interesting, but I found the science in this volume harder to get through than in the previous two books. The topics were all fascinating, but the technical depth, at times, was just too deep. I felt a little lost, probably due to the hypothetical nature of a lot of the science covered. I struggled to visualize concepts when theories got too technical.

I did learn a lot though, alongside the silly adventure of Darwin and the meddlesome wizards at Unseen U. It was nice that at least this time, they didn't have a choice but to meddle. 

The truth and humor mixed in this series is perfectly done and allows you to learn and laugh all at once. 

Read these first:
The Science of Discworld (Volume I)
The Globe: The Science of Discworld (Volume II)