Evolution: Biology
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Evolution: Biology |
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Basic Ideas: Similarities in Morphology and Anatomy |
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ContentSimilarities between living beings are of significant importance for evolution theory. Not only do they count as essential evidence of macroevolution, they also form the most important basis of the reconstruction of phylogenetic trees. The following article will show that the “evidence of similarity” for evolution is not substantive and that a lot of similarity findings are difficult to interpret by means of evolution theory. |
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Applied to the argument of similarity this means: It is noticeable that descendants resemble their immediate ancestors. This observation can only be made within species or basic types – not beyond them. If it is concluded from the similarity between e.g. man and chimpanzee that both descended from common ancestors, a purely theoretical extension of reasoning has occurred: What is valid within crossbreeding kinds is claimed to also be valid where “similarity on account of descent” is no longer observable. This kind of conclusion is not compelling. So the interpretation of the similarities as common origin is possible but not compelling because similarities are also to be expected on account of similar functions. Similar species often live in similar environment, take similar nourishment, breathe the same air, have to follow the same physical principles and so on. Therefore there must be similarities, however the species came into being. Now the objection is raised that many similarities cannot be explained by the function of the compared organs but only by common origin, for instance similarities in the skeleton of vertebrate limbs (pic. 45). It can hardly be proved, however, that certain similarities or differences are not caused by function. Moreover there are good functional reasons for the remarkable similarity between the limb skeletons, so the assumption of a common origin is not necessary. Additionally similarities can always be explained by the “handwriting” of the same creator. Like there are “trademarks” in technology or art that point to the same author (see pic. 46), this can as well apply to living beings (see article We can now state that similarities by themselves give no certain information about their origin. |
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Convergence |
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Within the theory of evolution not every similarity counts as evidence of common origin, though, but only – simplistically spoken – similarities with the same bodyplan of construction. Biologists call this kind of similarity homology and consider it to be an indicator for common origin. Some similarities however are thought to have evolved independently on different branches of the phylogenetic tree: convergence. Therefore convergences do not count as evidence for common origin. In many cases, though, a differentiation between homology and convergence is not objectively possible, a fact that is conceded by systematists without hesitation. An example is given in pic. 47. |
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Different complexes of characteristic features support contradicting constructions of phylogenetic trees. Often ideas of evolution theory are needed in advance to be able to differentiate homologous similarities from convergences. Therefore it is circular reasoning to draw a conclusion from homologous similarities to common origin. This is another reason for our observation: Similarities cannot count as certain evidence of common origin. |
Modular system |
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In many groups of animals and plants convergences are widespread (see Within the scope of a creation model the block-like arrangement of features is comprehensible ( |
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Conclusions |
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It is observable only within crossbreeding species that similarity is caused by origin: The offspring resemble the parents. This observation however cannot be made concerning similarities between different basic types. Here one would have to deduce from an observable field to an unobservable one. This kind of conclusion never is compelling. This is all the more so because there are other reasons than common origin that may lead to similarity. As many examples in technology or art show, similarity can be attributed to the same author. This interpretation is possible for living beings as well (see article in So the situation presents itself as follows: The observable data (the findings of similarity) are retrospectively included to in the already given concept of evolution. The data themselves do not “produce” or force a certain pattern of interpretation, on the contrary – it has to be presupposed. Whatever concept of origin is taken as a basis, only the result of emergence can be analyzed – not how it took place (see fig. 51). |
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The appearance of convergences can be made understandable by the creation model, because free combination of the features in the sense of a modular system can be expected. - |
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Overview 
Introduction
