That has been known to have happened. Perhaps it is a random walk after all? I guess
the first thing for the creationists to do would be to show that there is a trend of increased complexity.
Furthermore there is an interesting issue here that a random walk starting at one cell animals has
limited downward moving capabilities. It's a random walk with a wall at the lower end. Could the
"increase in complexity" be a mere random walk with a wall at one side?