The genetic material DNA is increasingly used to determine evolutionary relationships. Within a species, changes in DNA are spread by interbreeding. However, when a species splits into two, the genetic material of the two species becomes isolated, and what happens in one species no longer affects the other. Nevertheless, resemblances are present. Through time, as species split again and again, similarities with earlier ancestors become more and more attenuated. From such patterns, the closeness of relationship often can be teased out.
DNA analysis has been mostly useful with living species. With time, DNA
tends to become degraded, eventually to the point of being unusable. In the past, hair
recovered from archaeological or fossil sites has yielded DNA when the root portion is
present. Now, archaeologists are finding DNA from the shafts of hairs—not only
discernible, but possibly protected by the substance of the hair itself. If this holds
up, then not only will we be able to confidently identify the kind of animal a piece of
hair came from, but perhaps the relationships between now extinct forms.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.