Although we see evidence for microevolution, macroevolution is much more difficult to defend. In addition to genetic mutations and natural selection causing a change from one animal to another, macroevolution also proposes that organisms evolve from simple to more complex.
Macroevolution cannot be defended by the scientific method. No one has ever observed it, and scientists can’t reproduce it. Therefore, we must first look for historic evidence that macroevolution took place. If the plethora of plant and animal life forms we have today truly evolved from a single organism, we should have an abundance of fossils of organisms in transitional states.