When analyzing living beings, we frequently verify structures that make us believe in some ancestry in common and in the process ofevolution. However, these characteristics do not always reflect the evolutionary relationships between organisms.
→ homologous bodies
The homologous organs are those that may or may not perform the same function, but have an equal basic structure and the same embryonic development. This means, therefore, that individuals who have these organs have shared ancestry.
As an example of homology, we can mention the tetrapod members. Analyzing the members of amphibians, reptiles, birds and mammals, we realized that the number and disposition of bones are quite similar, which shows us the kinship relationship present there (See figure bellow). In this case, we have a similar structure, but with distinct functions, which reflect different lifestyles.
Structure of tetrapod limbs
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Since homologies are similarities resulting from a common ancestor, their analysis provides important information about the relationship between species.
Therefore, we consider homologies one of the evidence of biological evolution.→ Analogous organs
Analogous organs, in turn, do not reflect ancestral relationships and concern only similar functions. These similarities occur due to the convergent evolution, which leads to the appearance of similar characteristics even in individuals from very different groups. This is due to the fact that these characteristics favored survival in similar environments, representing, therefore, adaptations to the environment.
As an example of analogies, we can mention the wings of birds and insects. These animals have wings that guarantee their flight, however, the structures are quite different. Thus, the functions are similar, but they do not have the same embryonic origin, nor do they indicate ancestry.
By Ma. Vanessa Sardinha dos Santos
Would you like to reference this text in a school or academic work? Look:
SANTOS, Vanessa Sardinha dos. "Analogous and homologous organs"; Brazil School. Available in: https://brasilescola.uol.com.br/biologia/Orgaos-analogos-homologos.htm. Accessed on June 28, 2021.
