Similarities and Homology: Not Evidence for Evolution!


Red Pandas were once thought to be related to Giant Pandas based on similarities, however, DNA studies show that this isn’t the case.
Image used with permission from


One great evidence for evolution touted by its followers, is the similar structures found in many diverse and closely related organisms. If evolution were true, and all life has evolved from a single common ancestor, we should expect to see similarities present in organisms. However, using these similarities as evidence for evolution makes the argument fallacious on two counts.

The Fallacious Argument

  1. Evolutionists base the evolutionary tree of life (or, ‘phylogenies’) on the similarities found in animals. In other words, if two animals are similar, it is assumed they are closely related in the evolutionary scale. But for evolutionists to turn around and claim these same similarities ‘prove’ evolution is fallacious!
  2. This line of reasoning also commits the fallacy of Affirming the Consequent. Here’s why. Evolutionists claim: “If evolution is true, we would expect to see similarities in organisms. We do see similarities. Therefore, evolution is true.”This conclusion may not be true — there are other explanations for similarities in organisms, such as a common designer. To escape their argument being labelled as a fallacy, evolutionists might substitute the conclusion “therefore, evolution is true” with “therefore, evolution is probably true”. But this is also fallacious. We could say: “If the moon is made of Swiss cheese, it will have large depressions. The moon has large depressions. Therefore, the moon is probably made of Swiss cheese.” Adding ‘probably’ to the conclusion does not change it from being fallacious as it still commits the fallacy of Hasty Generalization.

Similarities Examined

Putting all this aside, is it really true that supposedly closely related organisms have similar structures? Yes, some vertebrates do have similar forelimbs — but this could also be the result of a common designer just as much as the result of common ancestry. This in itself overrules any claim that similarities are exclusive evidence for evolution. But the data isn’t as consistent as evolutionists would have you think. Proponents of Darwin’s theory believe that the eye evolved around 30 different times in different animals because there is no sequence to explain this similarity from a common ancestor. Shouldn’t we expect the eye to have evolved once (at most, twice or three times) in a single common ancestor? Evolutionists thought so too, but they cannot create any coherent theories to explain the origin of the eye in this way.

Scientists were convinced that the Red Panda was closely related to the Giant Panda based on many similarities such as extra thumbs, V-shaped jaw, similar teeth, and similar skulls. We now know from DNA studies that the Red Panda is actually more related to raccoons and not Giant Pandas or bears.

Seals and sea lions look extremely similar; but most evolutionists believe that seals evolved from a skunk or otter, while sea lions evolved from a dog or bear. Even though they are very hard to tell apart, seals and sea lions are not related.

Many organisms which are commonly thought to be unrelated also have similarities. Fish have fins and swim in water. But so do reptiles (Ichthyosaur) and mammals (dolphins). So according to the line of reasoning followed by evolutionists, why aren’t these animals closely related?


If similarities really did indicate common ancestry, why do birds have wings as-well as essentially unrelated mammals and reptiles?
Image from Wikimedia Commons user, ‘Joe Ravi’

Birds have wings. But so do mammals (bats) and reptiles (Pterosaurs). Yet they are not closely related and are thought to have evolved from an ancestor without wings.

Birds have duck-bills. But so do reptiles (hadrosaur) and mammals (platypus). Yet they are essentially unrelated and are thought to have evolved from an ancestor without a duck-bill.

Birds have bony eye rings. But so do reptiles (Ichthyosaur) and many fish. Yet they are essentially unrelated and are thought to have evolved from an ancestor without eye rings.

The placental mole and the pouched mole look extremely similar. In fact, one would be hard-pressed to tell the difference between them. Yet evolutionists think that the whale and the placental mole are more closely related than the placental mole and the pouched mole.

The placental mouse and the marsupial mouse are very similar. Yet, evolutionists believe that the placental mouse and the horse are more closely related than the placental mouse and the marsupial mouse.

Observer Bias

All these examples show the sheer folly of the similarity argument as evidence for evolution. But there is more than that — similarities are strongly subject to observer bias. For instance, the hyrax is classified the ancestor to elephants and sea cow based on teeth; while it is also classified the ancestor of horses and rhinoceros based on the ears. Dr. Daryl Domning said concerning this:

“Some scientists have challenged the hyrax, elephant, sea cow connection on the grounds of special anatomical features, like the shape of the teeth in hyraxes, which is much like that of elephants. A particular sac-like structure inside the neck related to the Eustachian tube, which resembles what you see in horses and tapirs, is not found in sea cows or elephants or other mammals. … In one commonly used approach, it boils down to a matter of counting characters on both sides and using what we call parsimony, the simplest explanation being that the relationship is wherever there is a greater number of characters in common.”[1] (emphasis added)

It all boils down to what a certain scientist sees as similar. There are many instances where scientists differ on what a particular organism’s ancestors were — and these differences in opinion are almost always based on similarities.

Convergent Evolution?

It is very common for an evolutionist to answer the previously-mentioned anomalies by pointing out that similar organisms could have evolved by means of convergent evolution. Convergent evolution basically says that two or more unrelated organisms evolved to have very similar characteristics independently. Not only does is this ‘explanation’ a cop-out, but it also undermines the whole principle of the similarity argument:
Firstly, it is irrational to claim that convergent evolution sufficiently explains all similarities in unrelated organisms (take the eye for instance which supposedly arose 30 different times!).
Secondly, it invalidates the similarity argument: if some similarities in unrelated organisms arose by convergent evolution, how do we know that other similarities in related organisms didn’t arise by convergent evolution?


The dilemma is such that evolutionists should drop the similarity argument. It is based on fallacious arguments, bad science, and finally, the very process used to explain unrelated similarities (convergent evolution) invalidates the whole argument! This is one ‘proof for evolution’ that should never be used.

comments powered by Disqus