Question

Why are the wings of a bat and the forelimbs of a horse considered homologous?

Answer 1

Hint: Evolutionary biology is the subfield of biology that involves the study of the history of the development of newer forms of life from the pre-existing ones in various periods on the earth. It studies the evolutionary processes like natural selection, speciation, common descents that lead to the diversity of life on the earth.

Complete answer:
Evolution is the unfolding of nature that brings about an orderly change from one form or condition to another resulting in the descending of modern organisms from ancient organisms over time. Evolution results in the production of new organisms that are more suitable or fit for the environment. Evolution occurs in all domains-stellar, inorganic, physical, chemical ,and biological. Types of biological evolution-microevolution, macroevolution, mega evolution, progressive evolution, retrogressive evolution, convergent evolution, divergent evolution, parallel evolution, quantum evolution, punctuated evolution, coevolution.
The most discussed biological evolution is convergent and divergent evolution.
Convergent evolution or Adaptive Convergence: The different species adapt to the same habitat and way of life. Functionally similar structures are formed by unrelated organisms. Organs having similar functions but different origins or structures are called analogous organs. The wings of birds and insects are homologous organs. Both of these unrelated species use wings for flight and yet their wings have dissimilar ancestral origins. The wings of birds are modified forelimbs and those of insects are outgrowths of the exoskeleton located on the mesothorax and the metathorax. Another example is the complex eyes of vertebrates, cephalopodes (squid and octopus) jellyfish, and arthropods (insects and crustaceans) that evolved separately but function for vision.
Divergent Evolution or Adaptive Radiation: Species of a common ancestor adapted to different habitats and ways of life. Related organisms form functionally different forms of a similar structure. Organs having similar structures but performing different functions are called homologous organs.
The wings of a bat and the forelimbs of a horse are considered homologous organs because they have the same fundamental skeletal structures, derived from the same embryonic origin, and evolved from the same structures but function differently. Both of them are of mammalian origins but use their forelimbs differently. The bats use their forelimbs for flying but the horses use them for running.

Note:
Examples of analogous organs: wings in insects and birds, stream-lined bodies and fins of fish and whales, flippers of penguins and dolphins. Examples of homologous organs: Bones of the whale's front flipper and bones of the human arm, the thorns and tendrils of Bougainvillea and Cucurbita, leaves and their modifications, roots, and their modifications.