Editing Mitochondrion (section)

===Human population genetic studies===
{{Main|Human mitochondrial genetics}}

The near-absence of [[genetic recombination]] in mitochondrial DNA makes it a useful source of information for studying [[population genetics]] and [[evolutionary biology]].<ref>{{cite journal | vauthors = Castro JA, Picornell A, Ramon M | title = Mitochondrial DNA: a tool for populational genetics studies | journal = International Microbiology | volume = 1 | issue = 4 | pages = 327–332 | date = December 1998 | pmid = 10943382 }}</ref> Because all the mitochondrial DNA is inherited as a single unit, or [[haplotype]], the relationships between mitochondrial DNA from different individuals can be represented as a [[phylogenetic tree|gene tree]]. Patterns in these gene trees can be used to infer the evolutionary history of populations. The classic example of this is in [[human evolutionary genetics]], where the [[molecular clock]] can be used to provide a recent date for [[mitochondrial Eve]].<ref>{{cite journal | vauthors = Cann RL, Stoneking M, Wilson AC | title = Mitochondrial DNA and human evolution | journal = Nature | volume = 325 | issue = 6099 | pages = 31–36 | date = January 1987 | pmid = 3025745 | doi = 10.1038/325031a0 | bibcode = 1987Natur.325...31C }}</ref><ref>{{cite journal | vauthors = Torroni A, Achilli A, Macaulay V, Richards M, Bandelt HJ | title = Harvesting the fruit of the human mtDNA tree | journal = Trends in Genetics | volume = 22 | issue = 6 | pages = 339–345 | date = June 2006 | pmid = 16678300 | doi = 10.1016/j.tig.2006.04.001 }}</ref> This is often interpreted as strong support for a recent modern human expansion [[Recent single-origin hypothesis|out of Africa]].<ref name="Garrigan-2006">{{cite journal | vauthors = Garrigan D, Hammer MF | title = Reconstructing human origins in the genomic era | journal = Nature Reviews. Genetics | volume = 7 | issue = 9 | pages = 669–680 | date = September 2006 | pmid = 16921345 | doi = 10.1038/nrg1941 }}</ref> Another human example is the sequencing of mitochondrial DNA from [[Neanderthal]] bones. The relatively large evolutionary distance between the mitochondrial DNA sequences of Neanderthals and living humans has been interpreted as evidence for the lack of interbreeding between Neanderthals and modern humans.<ref>{{cite journal | vauthors = Krings M, Stone A, Schmitz RW, Krainitzki H, Stoneking M, Pääbo S | title = Neandertal DNA sequences and the origin of modern humans | journal = Cell | volume = 90 | issue = 1 | pages = 19–30 | date = July 1997 | pmid = 9230299 | doi = 10.1016/S0092-8674(00)80310-4 | hdl-access = free  | hdl = 11858/00-001M-0000-0025-0960-8 }}</ref>

However, mitochondrial DNA reflects only the history of the females in a population. This can be partially overcome by the use of paternal genetic sequences, such as the [[genetic recombination|non-recombining]] region of the [[Y-chromosome]].<ref name="Garrigan-2006"/>

Recent measurements of the [[molecular clock]] for mitochondrial DNA<ref>{{cite journal | vauthors = Soares P, Ermini L, Thomson N, Mormina M, Rito T, Röhl A, Salas A, Oppenheimer S, Macaulay V, Richards MB | title = Correcting for purifying selection: an improved human mitochondrial molecular clock | journal = American Journal of Human Genetics | volume = 84 | issue = 6 | pages = 740–759 | date = June 2009 | pmid = 19500773 | pmc = 2694979 | doi = 10.1016/j.ajhg.2009.05.001 }}</ref> reported a value of 1 mutation every 7884 years dating back to the most recent common ancestor of humans and apes, which is consistent with estimates of mutation rates of autosomal DNA (10{{sup|−8}} per base per generation).<ref name="Nachman-2000">{{cite journal | vauthors = Nachman MW, Crowell SL | title = Estimate of the mutation rate per nucleotide in humans | journal = Genetics | volume = 156 | issue = 1 | pages = 297–304 | date = September 2000 | pmid = 10978293 | pmc = 1461236 | doi = 10.1093/genetics/156.1.297 }}</ref>