Question

What is organic evolution? Describe Palaeontological and Embryological Evidence in favour of organic evolution.

Answer 1

The origin of life is considered to be the result of a long series of physiochemical changes, which brought about chemical evolution first and then biological evolution. The evolution upto the formation of coacervates is termed as chemical evolution or organic evolution in which complex organic compounds were formed that are essential further for the formation of many cellular structures.

Evidences from palaeontology:

Palaeontology is the study of fossils which are the remains of ancient organisms. There are many types of fossils like:

1. Body fossils which are the hard parts of organisms.

2. Subfossils which are the remains of plants and animals.

3. Microfossils which are less than 0.5 mm in size

4. Macrofossils which are larger than 1 cm in size.

5. Pseudofossils which are inorganic objects.

6. Unusual fossils which formed as a result of combinations of conditions and events.

7. Trace fossils which are the footprints and trails left by the past organisms.

8. Coprolites which are the trace fossils of animal faecal matter or their droppings.

Evidences from embryology:

It includes the study of life histories of individuals which give an idea about their descendants.

Resemblance among late vertebrate embryos:

There is a close similarity among the embryos of all vertebrates like-

1. Presence of various similar structures like Gill clefts, notochord, ears, rudimentary eyes etc.

2. Replacement of notochord by the vertebral column.

3. Development of tetrapod embryo as limb buds.