One of the subjects that pose the worst dilemmas for evolutionists is those organs with exceedingly complex structures. Evolutionists claim that living things with very complex organs in common but with no common ancestor must have undergone evolution independently of one another.

According to evolutionists, these living things developed in parallel to one another and came to possess similar organs; however this might have come about. To cite one example, the structure of the eye in squid and vertebrates is identical, though no attempt is made to construct an evolutionary relationship among these creatures. Evolutionists claimed parallel evolution to account for the origin of these organs. However hard it is to explain how such developed organs came into existence once, it's quite impossible to account for how they might have come into being twice, and independently.

Briefly, the only difference between parallel evolution and other forms of evolution is that the former needs even more chances to come about. The more flawless structures appear in living things, the less scientific appear evolutionists' scenarios.