Theory of Evolution
In Whales and other Cetaceans, one can find small vestigial leg bones deeply buried within the back of the body. These are remnants of their land-living ancestors' legs
The wings of Ostriches, Emus, and other flightless birds are vestigial; they are remnants of their flying ancestors' wings.
Humans also bear some vestigial behaviors and reflexes. The formation of in humans goose bumps under stress is a vestigial reflex its function in human ancestors was to raise the body's hair, making the ancestor appear larger and scaring off predators.
The evolutionary history of a species can be seen in its DNA sequences. The more closely related two species are, the more similar their DNA sequences.
The very existence in of DNA every living thing on earth is, in itself, strong evidence of common ancestry. It would be highly unlikely for DNA to have evolved independently so many times, over and over.
We can see common ancestry in the chromosomes, themselves:
There are at least 26 species of the protozoan Tetrahymena, all of which are nearly identical in structure, BUT there are enormous differences between their homologous proteins. The same is true of the more than 2000 species of fruit flies.
Comparing selected proteins, evolutionists hope to show not only phylogenetic relationships but also a "molecular clock" that will provide a relative time table for evolution. For example:
alpha chain of hemoglobin differs between horse and man by about 20 amino acids. Evolutionists believe that the horse and man "diverged" about 100 million years ago THEREFORE, the evolutionary rate of hemoglobin is ONE amino acid per 5 MILLION years. This rate is then extrapolated to other differences and in this way a "phylogenetic tree" is established complete with DATES!