Biologists agree that human beings evolved from a fish, but they disagree about which species of fish  Since biologists agree that frogs are definitely related to the species of fish from which human beings evolved, on the basis of a close match between the mitochondrial DNA of lungfish and that of frogs Dr  Stevens-Hoyt claims that this ancestor must be lungfish  Dr
Grover, on the other hand, contends that mitochondrial DNA evolves too rapidly to be a reliable indicator of relationships between species over long periods of time, and citing the close chemical match between the hemoglobin of coelacanths (a saltwater fish) and that of tadpoles, claims that human beings must be descended from coelacanths
It is an assumption that both parties to the dispute use as a starting point for their arguments about human evolution.