Why Sculpt Evolution?
Life is defined by the ability to reproduce. Replication is not only remarkable, it is also powerful: engineer an organism to do something useful, and its offspring will perform the same trick. But let them reproduce for long enough, and they often stop doing what we want.
This occurs because altering a trait typically harms the organism's ability to reproduce. Any individuals that acquire a mutation reversing our alteration - or those that never had it to begin with - will reproduce more often than those that still have it. Over generations, organisms that lack our trait will out-replicate those that have it, until most or all of the population no longer does what we want. This is evolution.
Of course, we can sometimes control the environment to favor organisms with the trait that we want. If we do this and a mutation arises that improves the trait - often in a way we could not have predicted - that, too, will be favored and take over the population. The organisms will not only get better at doing what we want over time, they will often be far superior to our best designs. This, too, is evolution.
The challenge is to influence the forces that determine the ability to reproduce. By learning to sculpt evolution, we can discover how to reliably engineer living systems in the laboratory, factory, farm, and even the wild.
For the truly fascinated, the first chapter of Kevin's dissertation is a comprehensive pictorial introduction to directed evolution.