What is Molecular evolution?
'''Molecular evolution''' is the process of evolution in [[DNA]], [[RNA]], and [[protein]]s. Molecular evolution emerged as a scientific field in the 1960s as researchers from [[molecular biology]], [[evolutionary biology]] and [[population genetics]] sought to understand the structure and function of [[nucleic acid]]s and protein. Some of the key topics have been the evolution of [[enzyme]] function, the use of nucleic acid changes as a [[molecular clock]] to study species divergence, and the origin of non-functional or junk DNA. Recent advances in [[genome|genomics]], including whole-genome sequencing, and [[bioinformatics]] have led to a dramatic increase in studies on the topic. In the 2000s, the role of [[gene duplication]], the extent of [[adaptation|adaptive]] molecular evolution versus neutral [[genetic drift]], and the identification of molecular changes responsible for various human characteristics especially those pertaining to [[infection]], [[disease]], and [[cognition]]. == Molecular study of phylogeny == Molecular systematics is the process of using data on the DNA, RNA, or proteins to resolve questions in [[phylogeny]] and [[taxonomy]].<ref name=Graur00>{{cite book |author=Graur D. and Li W.-H. |year=2000 |title= Fundamentals of molecular evolution |publisher=Sinauer}}</ref><ref name=Gillespie91>{{cite book |author=Gillespie, J.H. |year=1991 |title=The causes of molecular evolution |publisher=Oxford University Press, New York| isbn=0-19-506883-1}}</ref> The idea is to place groups in their correct position on the evolutionary tree. This corrects their [[biological classification]] from the point of view of [[evolution]]. The technique has already led to major changes in the taxonomy of living things, including the names for higher categories, which had been stable for well over a century. Molecular systematics has been made possible by techniques for [[sequence analysis]]. This gives the exact sequence of nucleotides or bases in either DNA or RNA. At present it is still expensive to sequenc