Comparitive Anatomy Study Guide

Comparative anatomy is the study of similarities and differences in the body structure of living beings to find evolutionary relationships between species.

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Scientists always try to find more and more evolutionary relationships between species. But why do they do that? They are in search of a common ancestor, of course. Scientists have come so far by understanding the concept of evolution that organisms undergo for their survival. You must've seen animals with the same body structures as we have. Comparing and finding prehistoric relationships between ancestors and descendants based on their body structure is the most basic and important step in tracing evolution.

What is comparative anatomy?

Definition of comparative anatomy: This is the study of similar and different structures in organisms.

In simple words, the comparison of similarities and differences in the body structure of living organisms to trace evolutionary relationships with their ancestors. The only base that we can take for tracing evolution is the anatomy of organisms and the changes that they have undergone.

Anatomical comparisons in living organisms also facilitate the scope of classification as per the similarities and differences they have. The main use of comparative anatomy is to trace evolutionary relationships in organisms, and many biologists like Lamarck and Buffon have used it in the past years.

Purpose of comparative anatomy:

The main purpose of comparative anatomy is to find differences and similarities between the body structure of species to predict whether they are related to a common ancestor or not.

How does comparative anatomy support evolution?

Comparative anatomy and evolution are closely related to each other.

  • Anatomy means the study of basic human structure. Nothing can be simpler than comparing organisms and tracing their history with their ancestors based on the body structure.
  • Changes in body structure take place when organisms need them for their survival.
  • These changes in body structure over a large period lead to anatomy evolution in living organisms.

Comparative anatomy of humans and gorillas Source

Areas of study in comparative anatomy:

Comparative anatomy has three areas of study based on three different main structures. These structures will help you understand “ how comparative anatomy provides evidence for evolution.”

Homologous structures

Some related organisms have similar structures in some parts of their body structure. These structures are the same because they must've inherited them from a common ancestor. But the descendants use these structures differently. Such body structures are termed homologous structures.

One example of homologous structures can be the forelimbs of humans, animals, dolphins, rodents, bats. The functions of every organism are different from others.

Analogous structures

Analogous structures are found in unrelated organisms with similar body structures. The structures are similar because they were meant to perform the same functions, and these structures aren't inherited from a common ancestor.

For example, bats and birds have the same wing structure, but birds are closely related to animals, and bats are not. Wings facilitate the same function, but their wing structure shows they inherited from different ancestors.

Vestigial structures

Organisms possess some parts in their body structure that are usually of no use. Those parts of the body structure shrink over a period of time. After some years, either those parts vanish or have a very small existence in body structure. Such body structures are known as vestigial structures.

An example of vestigial body structure can be the human tailbone. Traces show that prehistoric ancestors of humans had tails similar to animals, but they were of no use.

Different types of structures in comparative anatomy Source

Comparative embryology

  • If you're studying evolution, you should also consider how organisms came into existence, including the basic process of forming new organisms.
  • Embryology includes the study of the formation of the embryo, its growth, and its development process of giving birth to a new individual.
  • Comparative anatomy means the study of similarities and dissimilarities in the embryos of living organisms of different species. Embryo shows the evolutionary relationship of organisms.

Comparative anatomy and physiology

  • Comparative anatomy is the study of similarities and differences in the body structure of organisms. In comparison, the study of the function of those structures is known as physiology.
  • These concepts are closely related to each other and can help find evolutionary relationships in different species.


  • The study of different body structures of living organisms and comparing those structures is known as comparative anatomy.
  • Anatomical comparisons can help find evolutionary relationships in many ways, mainly with the help of different body structures like homologous and analogous.
  • Comparative embryology, which is the study of the structure of embryos of living organisms, can also assist in tracing the origin of species, as most of the organisms give birth to their offspring from embryos.


1. What is the purpose of comparative anatomy?

The purpose of anatomy is to find the differences and similarities in living organisms' body structure to trace the changes they must've acquired during evolution from their common ancestor.

2. What are the 3 structures of comparative anatomy?

The three structures of comparative anatomy are as follow:

  • Homologous structures
  • Analogous structures
  • Vestigial structures

3. What is comparative anatomy?

The study of similarities and dissimilarities in the body of living organisms is known as comparative anatomy.

4. What is comparative anatomy and embryology?

  • Comparative anatomy: The study of similar and different structures in organisms.
  • Embryology: Embryology includes the study of the formation, growth, and development of new living organisms.

5. What is embryology and development?

Embryology and development mean the development of an embryo from the very beginning, including the formation of gametes, fertilization, the formation of the zygote, embryo formation, and lastly, the birth.

6. Give an example of comparative anatomy.

Comparative anatomy examples are as follows: Traces show that the forelimbs of humans, animals, birds, dolphins, rodents, bats have the same structure, yet those structures have been changed because of evolution as per their need.

7. What is an embryo?

The embryo is the first stage of information of new living organisms that produce through the sexual mode of reproduction. Embryo forms before the organisms get their actual basic body structure.

8. What is an example of embryology?

Studying a human embryo and observing its growth from the very beginning to when it gets basic body structure can be an example of embryology.

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  1. Embryology. https://www.biologyonline.com/dictionary/embryology. Accessed 11 Dec, 2021.
  2. Comparative anatomy. https://www.britannica.com/science/comparative-anatomy#:~:text=comparative%20anatomy%2C%20the%20comparative%20study,of%20evolution%20from%20common%20ancestors.&text=Homologies%20of%20the%20forelimb%20among%20vertebrates%2C%20giving%20evidence%20for%20evolution. Accessed 11 Dec, 2021.
  3. Comparative Anatomy. https://flexbooks.ck12.org/cbook/ck-12-biology-flexbook-2.0/section/5.16/primary/lesson/living-species-bio/. Accessed 11 Dec, 2021.