I finished this book a month or two ago so the details are now foggy. However, I do know that I loved it. The author's writing style is very accessible. I never got bored and was amazed by how many times the subject matter changed course given that it is a science book. Many science books tend to beat the same horse repeatedly. Not so here.
Even if you are familiar with some of the topics covered, you will find much to enjoy. For instance, I read an entire book on Barbara McClintock previously, yet I found the chapter that dealt with her to be fresh even with all the prior knowledge.
If nothing else, you'll never look at guinea pigs and rats the same way again.