If you spend any time doing even a cursory review of the structure of animals it becomes pretty clear how evolution has progressed and shaped the planet's plants and animals. (Ever wonder why a whale has a femur?
) 4 billion years is a VERY long time. Hard for many to even fathom.
"The Panda's Thumb" by Stephen Jay Gould is an excellent read. (I'm assuming everyone has already read "On the Origin of Species" by Charles Darwin
)
Having said that, if you want to believe in something else, I have no problem with that either. As long as it doesn't affect me negatively.