Question

What is organic evolution? How do embryological studies provide evidence for evolution?

Answer 1

Organic evolution refers to the slow and gradual process by which living organisms have changed from the simplest unicellular form to the most complex multi-cellular forms that are existing today.Organic evolution primarily involves modifications in the existing organisms and the inheritance of these modifications.There are several theories that try to explain the mechanism of organic evolution.Lamarckism is one of the earliest theories on evolution proposed by J.B.Lamarck. According to Lamarckism, organic evolution occurs due to the inheritance of acquired characters.Darwinism is the theory proposed by Charles Darwin. Darwinism explains evolution in terms of over-production, struggle for existence, variations, survival of the fittest and natural selection.Mutation theory proposed by Hugo DeVries attempts to find the sources of variations in mutation occurring in individual organisms.
The study of one type of evidence of evolution is called embryology, the study of embryos. An embryo is an unborn animal or human young in its earliest phases. Embryos of many diff. kinds of animals, birds, mammals, reptiles, fish etc look very similar and it is often diff. to tell them apart.

Answer 2

Organic evolution occurs because of changes in a species which appear generation after generation and accumulate to form a new species.

The embryology of different vertebrates provides very strong evidence of different

vertebrates which show striking similarities. There is an obvious similarity between embryos of fish, amphibians, reptiles, birds and mammals. A comparison of embryos

of vertebrates shows that all have gill slits even though they do not remain later in life(except in fish). This indicates a fundamental step which is common to all vertebrates and supports the idea of a common ancestor. Other features which do

not exist in the adult form but appear in the embryo include limb buds in dolphins and tail buds in humans.

This shows that species sharean ancestor, so their developmental processes occur similarly regardless of other changes which have occurred because of their

divergence.