suppose that mice and humans differ by 30 substitutions in their globin genes, and rats and mice differ by five substitutions. on the basis of other evidence, we know that the ancestor to humans and mice lived 84 million years ago. assuming the molecular clock is operating, rats and mice split from each other million years ago.

One of the newest applications of cell technology is called cybrid embryos. this process involves replacing the nuclear material of an animal cell with human nuclear material. how might this process affect public policies about research by using stem cells? the same policies and concerns about the use of human embryonic stem cells would most likely apply. the embryos would most likely be treated like traditional animal embryos and regulated accordingly. the process of forming cybrid embryos would most likely be banned by government regulators. the embryos would be treated as regular cells because they are not fully human in origin.