From the introduction:
I always wanted to try a story featuring the deep-future history of human expansion into the universe. Having been an evolutionary paleobiologist for roughly 20 years, I have a fully non-Trekkian perspective: while I anticipate broad success on the part of Mankind in their eventual radiation to the stars, I look at it as the spread of a plague. The rationale for this somewhat unflattering view is that Man has evolved with the potential (and the extreme likelihood) for not only distributing himself across the universe, but also for acting as a vector for Earth’s viruses, fungi, weeds, spiders, roaches, rodents, pigeons, and dogs. In short, our biosphere is invasive and never takes no for an answer; Man is ideally poised to spread Earth’s biosphere like wildfire through the galaxy.