Here we will understand how to define analogy. The analogous structures and homologous structures are used to study the course of evolution. The study of these structures comes under the field of morphology. Under morphology, we study the external structures of an organism and also about their functions in the organism. On the other hand, anatomy refers to the study of the internal structures of the organism and its study of function. From the beginning of the universe, there are a lot of organisms that are present on the earth and they all are of a very diverse nature. So to make our study of these organisms easier we started classifying them under similar characteristics. The analogous and homologous organs help us to understand and characterize certain sets of organisms under each other. Also, the study of analogous and homologous structures gives us evidence of evolution. After making our studies we can compare their morphology and anatomy and this can surely give us an edge in studying these organisms and also the evolution. The study of analogous and homologous organs is termed an understudy of evolutionary relationships. This helped us to define analogy and further, we will learn about an example of analogous organs.
These structures are not anatomically similar. This means that they are made up of different parts of the body but they serve the same purpose. These structures are different in different organisms but they share or perform similar functions. This also means that externally these structures may not look similar to each other. This property when the structures are showing analogous nature is known as an analogy. Also, it is seen from the studies that the analogous structures do not have common ancestry but these structures are placed under the same group because of their similarity in performing similar functions. This gives us a clear answer to our question of how do analogous structures evolve. Now we will learn about some analogous structures examples.
Wings of Butterflies and of Birds: This is one of the example of analogous organs. We know that birds have a vertebral column so they are vertebrates and butterflies do not have vertebral columns so they are invertebrates. But they both have wings and their wings perform the same function that is flying. But when we look closely, their internal designs and the components from which both wings are made are very different. This shows or gives us an understanding that these structures are evolved differently but as they serve the same purpose, so they are showing convergent evolution. This is because of the adaptations that they need and also the presence of similar habitats. So this can be concluded from this example of analogous organs that these structures have evolved from convergent evolution.
Eye of Octopus and Eye of Mammals: The position of the retina in the eye of the octopus and the eye of the mammals different and this makes them different internally but these both serve the same purpose of vision.
Flippers of Penguins and Dolphins: Penguin is a bird whereas the dolphin is a mammal. Both of these organisms have the presence of flippers. They are different in internal structures but they serve a common purpose that is helping in swimming.
Sweet Potato and Potato: Potato is a modified stem and sweet potato is a modified root. They have originated differently but they serve the same purpose of storing food.
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After giving an answer to define analogy and also learning about analogous structures in a sentence, now we will learn about homologous structures. These structures are different from analogous structures. These structures have similar anatomy but they have different functions. A very good example to explain it can be seen when we study the structure and function of forelimbs in mammals. Let us take some examples such as man, cheetah, whale, bat. In all these four organisms the structures are evolved from the same line of evolution. They are made from forelimbs. But they serve different functions such as in man forelimbs are used to hold things, in cheetah they are used for running, in whales they are used for swimming and in bats they are used for flying. So this way we can see that the homologous structures have evolved from the same course of evolution but they serve different purposes. We can get to the conclusion that the homologous structures are a result of divergent evolution. Some more examples are:
Vertebrate Heart and Brain: The basic plan of the heart and brain in almost all organisms is the same but their complexity and varied degree of specialization make them different from each other.
Thorn of Bougainvillea and Cucurbita: They are made from the same course of evolution but one has developed as a thorn and the other has become a tendril.
1. What are Vestigial Organs?
Answer: These organs are the ones that are remnants of the vestigial organs. This can be seen from these organs that in our ancestors they were completely functional but in our present time, they are not present because they were not used for a long time. They help in making an evolutionary study in the course of evolution because these organs become vestigial and it helps us to trace back to the times from where they were present in us. Some examples of these types of organs are the reduced tail bones and the absence of nictitating membranes of the eye.
2. Explain Some Theories That are Related to the Origin of Life.
Answer: Some of the Theories That are Related to the Origin of Life are:
Theory of Special Creation: This theory was given by Father Suarez. He stated that God created earth or we can say life in six days with the help of some supernatural powers. God created human beings on the sixth day of creation.
Theory of Catastrophism: This theory was given by Cuvier. He stated that after certain gaps there are some catastrophic events or mass destruction events that take place on earth and in these events life is completely washed out and then a new life is created after that.
Theory of Biogenesis: A swan neck flask experiment was conducted by Pasteur and that resulted in giving a statement about this theory that life arises from pre-existing life.