Comparative anatomy

Comparative anatomy is one of the strongest forms of evidence for the evolution of organisms. Aristotle presents more information about the field of comparative anatomy. He was the first of the ancient Greeks to analyse animals methodically. He studied animals that are favoured for their detailed descriptions of more than 500 kinds of birds, reptiles, mammals, fish, insects, amphibians, and many other invertebrates. In his animal studies, he explores and analyses their structure, physiology, behaviour, development, and ecology. In the human body, an example of an anatomical part is the inner ear or skeletal muscle.

Comparative anatomy

Comparative anatomy is the study of anatomical variability between two species of an organism. In this study, a variety of species can be compared. A scientist using comparative anatomy could hypothesise the evolutionary relationships between an ostrich, a blackbird, and a bat. So, the blackbird and the bat are more related based on size. But the scientist can immediately observe that the bat is covered in hair, while the blackbird has feathers.

Georges Cuvier, in full Georges-Leopold-Chretien-Frederic-Dagobert, Baron Cuvier, (born August 23, 1769, Montbeliard died May 13, 1832, Paris, France), French zoologist and statesman, who established the sciences of comparative anatomy and palaeontology.

Concepts of comparative anatomy

There are two vital concepts of comparative anatomy, including homologous structures and analogous structures. 

Homologous structures

The structures that are anatomically very close in embryological form and the development of their related species, but have different roles because they originated from a common ancestor. These are called homologous structures, which are skeletal elements or organs of an organism. 

Analogous structures

The structures that are homogeneous in their unrelated species, but serve the same purpose are called analogous structures. This is generally because the species live in the same environments and share similar ecological functions.

Analogous structures are the result of concurrent evolution. So, body parts can emerge, or reposition, based on the function. The species that are impacted by convergent evolution are referred to as homoplasy.

Compatibility between homologous and analogous structures

• Homologous and analogous structures achieve adaptations to the environment.

• Both the homologous and analogous structures are derived from evolution.

Differences between homologous and analogous structures

The distinguishing character between homologous and analogous structures can be based on ancestry and function:

• Homologous Structures: Homologous structures are the structures that emerged from a common ancestor but do not serve the same task. 

• Analogous Structures: Analogous structures are structures of different species with the same functions. 

Examples

Homologous structures 

• Giraffes have long necks, lengths up to eight feet, and weigh over 600 pounds. They contain only seven neck bones or cervical vertebrae. These bones are about one foot in length. Humans also have cervical vertebrae, but they are shorter than those of the giraffe. 
• The limbs of mammals are a good example of homologous structures. The structure of the limb consists of a large upper arm bone, two lower arm bones along a collection of smaller bones in the wrist area. 
• The human arm is very homogeneous to the legs of cats, and the wings of bats, the flippers of whales, from an anatomical point of view. The structure of the limb is the same, but their functions are varied such as swimming, flying, and walking.

Analogous structures 

• The various flying animals such as insects, bats, birds, and even fish have wings. But, these wing structures support the same activities for different animals, the bone structures, wing coverings, shapes, and sizes might vary. 
• One of the quick understandable analogous similarities is concerning the fins of various animals. For Example, the fins present in birds, like mammals, and dolphins, involve the same work. But both are from different classes of vertebrates,  so their evolutionary range must be different.

Importance of comparative anatomy

Comparative anatomy plays an important role that helps to identify evolutionary relationships between organisms and whether or not they have common ancestors. But, there is also significant evidence of evolution. Anatomical similarities between organisms guide the idea that these organisms evolved from a common progenitor

Comparative anatomy kit

The comparative anatomy kit is designed for students to have extensive dissection experience to understand the anatomy of vertebrates. Students can also consider whether the anatomical differences of the animals are well-favoured in their specific habitats and responsibilities in the environment.

Conclusion

Comparative anatomy is nearly related to phylogeny and evolutionary biology. The study of comparative anatomy is essential to observe the variations in evolutions. Evolution helps the organism to support itself in the environment. Homologous and analogous structures are two kinds of structures found in species that emerged as a result of opposed evolution by conformational to the environment. The organisms which have homologous structures evolved from a common ancestor. Analogous structures arise from the result of convergent evolution. The most significant comparison between homologous and analogous structures is the origin of individual species.