Question

What is organic evolution? Describe palaeontological and embryological evidence in favor of organic evolution.

Answer 1

Hint: Evolution can be defined as sequential events that took place in the past and the changes that took place in the characteristics of a species over numerous generations and help in the process of natural selection for keeping the existence of life on the earth. Fossils are the main evidence that can support the theory of evolution.

Complete answer:
Organic evolution: The origin of life is considered as the result of a long series of physiochemical changes. These changes lead to chemical evolution as well as biological evolution. The formation of coacervates in the early development of earth is termed as chemical evolution or organic evolution.
Evidence from paleontological studies: Paleontology is the study that deals with fossils. Fossils remain unchanged though time has passed and the ancient organisms. Evidence of this study are as follows:
-Body fossils were developed from the hard parts of organisms.
-Subfossils are examples of the remains of plants and animals.
-Microfossils are less than 0.5 mm in size.
-Macrofossils are larger than 1 cm in size.
-Pseudo fossils are inorganic objects.
-Unusual fossils formed as a result of combinations of conditions and events.
-Trace fossils are the footprints and trails left by past organisms.
-Coprolites are the trace fossils of animal fecal matter or their droppings.
Evidence from embryological studies: It can be defined as the study of life histories of individual species which give an idea about their descendants. This study explains the similarity among embryos of late vertebrates.
There is a close similarity among the embryos of all vertebrates which is as follows –
-Presence of similar structures like Gill clefts, notochord, ears, rudimentary eyes, etc.
-Replacement of notochord that is present during the embryonic condition by the vertebral column which is seen in adults.
-Development of limb buds which results in the formation of tetrapod embryos.

Note: The embryological study was first done by Haeckel, who defines this phenomenon by a phrase – Ontogeny recapitulates phylogeny that means the development of an organism or ontogeny explains the evolutionary history and all the intermediate forms of ancestors of a species, called the phylogeny and recapitulation means the development of an embryo which is followed by the evolutionary history of an organism.