Jacob's Ladder delivers a remarkably lucid explanation of what the sequencing of the human genome really tells us. Decoding the sequence, evolutionary biologist Henry Gee shows, is just the beginning: seeing the letters and words. The next frontier is in understanding snatches of conversation between genes—how they interact to direct the growth of an organism. Gee takes us into the heart of that conversation, illuminating how genes govern a single egg cell's miraculous transformation into a human being, and how they continue to direct that person's day-by-day development throughout a lifetime.

Gee tells the story of what we know about the genome today and what we are likely to discover tomorrow. As our knowledge advances, we will be able to direct with increasing authority the conversations between genes: not only performing medical interventions but also creating whole scripts directing birth, ancestry, and diversity in a brave new world.