Comparative Embryology:

Closely related organisms go through similar stages in their embryonic development. At embryonic stage of development, similarities between fishes, frogs, snakes, birds, humans, and all other vertebrates are much more apparent than differences. As development progresses, the various vertebrates diverge more and more, taking on the distinctive characteristics of their classes.

For example

All vertebrate embryos go through a stage in which they have gill pouches on the sides of their throats. In fish, for example, the gill pouches develop into gills; In terrestrial vertebrates, these embryonic structures become modified for other functions, such as the Eustachian tubes that connect the middle ear with the throat in humans. Homology in structure. Comparative embryology can often establish homology among structures, Such as gill pouches, that become so altered in later development that their common origin would not be apparent by comparing their fully developed forms.

Molecular Biology:

Molecular biology has thus provided strong evidence in support of evolution as the basis for the unity and diversity of life. For example. Proteins and Genetic products Evolutionary relationships among species are reflected in their DNA and proteins, in their genes and gene products. If two species have genes and proteins with sequences of monomers that match closely, the sequences must have been copied from a common ancestor. Common genetic code It brings evidence that all life is related. Common Respiratory Proteins. Taxonomically remote organisms, such as humans and bacteria, have some proteins in common. For instance, cytochrome c, a respiratory protein is found in all aerobic species