The absence of an involving plot is the man cause of this, but the easily forgettable characters contribute significantly as well. The most memorable part of this book comes near the end. Graves have been robbed of their corpses. Even I have to admit that picking a blurb apart for inaccuracies is pedantic in the extreme, but I think the carelessness displayed here is symptomatic of the entire book. Only Mr Peel could tell us for sure, but I'm guessing he knocked this baby over in a couple of weeks for the boys at Virgin.
Evolution is riddled with problems of both plot and character that suggests a rush job.
That's about the nicest thing that can be said really. It's a pity someone couldn't give Mr Peel some ideas for his. The Fourth Doctor's character is admittedly not the easiest to capture on the page, but Tom really got up on the wrong side of the bed for this adventure. Sarah is a little closer to her TV persona, but not in any way that endears her to the reader. Perhaps feeling that characterisation was not his strong point, the author doesn't bother giving any to the other dozen faceless names that inhabit the story.