So far, of all the books I've read on evolution and related topics, Finding Darwin's God has been my favorite. Your Inner Fish comes in a close second if it doesn't tie.
For those that haven't heard of this book, Inner Fish is written by the guy that was one of the lead researchers on the team that discovered the tiktaalik fossil.
The book starts off by explaining how the fossil was discovered: Scientists knew that in the early Devonian period, there weren't any tetrapods, but by the end there were. This left a window in which they must have evolved (assuming evolution were true). Thus, they looked for exposed surface rocks dating from that era. One of the best unexplored sites for it ended up being on Ellesmere Island near Greenland. Sure enough, Shubin's team discovered exactly what evolution had predicted (something that shouldn't have happened if Creationists were right).
What Shubin then spends the majority of the rest of the book discussing is how many features we have in our bodies today are remnants of developments like the ones tiktaalik went through. Specifically, much of our arms and hands were developed and their basic plan laid out by species like tiktaalik and then modified through evolution to suit new needs.
Shubin points out that this is spectacularly revealed when we look at other features in the human body which make no logical sense, such as nerves and arteries which take the oddest detours to reach their intended targets. He likens it to a new research facility in his university:
I had been given space for a research laboratory in a hundred-year-old building and the lab needed new utility cables, plumbing, and air handling. I remember the day when the contractors first opend the walls to get access to the innards of the building. Their reaction to the plumbing and wiring inside my wall was almost exactly like mine when I first opened the human head and saw the trigeminal and facial nerves. The wires, cables, and pipes inside the walls were a jumble. Nobody in his right mind would have designed a building from scratch this way, with cables and pipes taking bizarre loops and turns throughout the building.Similarly, to understand the design of a species, you must understand its history, just as one must understand the history of a building to understand the wiring.
And that's exactly the point. My building was constructed in 1896, and the utilities reflect an old design that has been jury-rigged further with each renovation.
The next several chapters deal with numerous other components of the human body and how we can find structures that preceded them still intact in other species today. Namely, he skims into embryology and discusses how homologous components in the embryo develop into wildly different structures in different species. He goes through Hox genes and development of the olfactory, visual, and auditory systems.
But so what? A Creationist could easily claim (and do they ever) that these similarities due to a common designer. But in all of these, Shubin emphasizes that all of these ways of relating species give a nested "Russian Doll" structure. And that's really the key. This picture of groups within groups (taxonomy) fits perfectly with the evolutionary model and should not in any way be expected if a designer was popping out species here and there, even if similar designs were used! Additionally, on top of all this amazingly self consistent family tree from taxonomic grouping, it can all be checked against the fossil record and by making more classification trees from genetic evidence (such as ERVs).
Shubin doesn't hammer this point home as well as he could have, and that's my main problem with this book. Instead of reminding the reader of all these additional, consistent pieces Shubin skims over them. However, he does at least nod in their direction (without explicitly stating them) by saying
Some groupings are so strong, that for all intents and purposes, we consider them fact.... Our fish-to-human framework is so strongly supported that we no longer try to marshal evidence for it - doing so would be like dropping a ball fifty times to test the theory of gravity.Overall this is a fantastic book and I'd recommend it to anyone. It's very approachable even without much science background. There's a few parts that get more in depth and would require a more methodological reading for someone not at least passingly familiar with genetics and embryology. But then again, those are some of the coolest parts in the book. One of my favorites was the discussion of the hedgehog genes. It's a great example of gene regulation during development and I'm doing more reading on it (and other such traits) since we just finished talking about gene regulation in my Bio I class.
As a side note: There's a few versions of this book out there. The one I see most often in book stores is the "Vintage" edition. I have the January 2009 one and this one contains a nice afterword which follows up on a few of the developments with tiktaalik since the first printing of the book. It gives another perfect example of how tiktaalik is a stunning intermediate fossil. When they dissected the skull, the team found a bone wonderfully proportioned between a larger ear bone from earlier, aquatic species and the later smaller bone of more terrestrial ones.