The relative age of a fossil can be determined by comparing its to other fossils within the same rock layers below younger fossils.

The relative age of a fossil can be determined by comparing its Index fossils to other fossils within the same rock layers below younger fossils.

Explanation:

Relative dating is one of the two methods used to determine the age of fossils does not determine when events occur, but it shows the order of the events as they occur. Relative dating compares similar rocks and fossils of already known ages to the ones the fossils that are yet to be determined so as to get their approximate age. The relative age of a rock is the age of that rock when compared to the ages of other rocks.

A fossil record can show the relationship that existed between different plants and animals. Often we Index fossils are used in dating other fossils found in the same strata. Index fossils point out the relative age of the layer where it is found,

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."