quote:
Evolution produces organisms more fit to survive. It is absolutely blind toward any sense of progress, either from lower to higher or from simple to complex. The sole guiding factor is the ability to pass genes on to the next generation. Evolutionary success means passing genes on, evolutionary failure means not passing genes on. Whether the descendent organisms are simpler or more complicated, whether they are "higher" or "lower" (whatever that means), is irrelevant.
Sometimes evolution proceeds from more complex to less complex.
For example, the evolutionary history of the horse shows that it used to have multiple toes on each limb, but now only has one toe, with vesigial splint bones on either side of the main, large tarsal (cannon) bone.