Mitochondrial Eve 89792 move=:edit= 225819465 2008-07-15T15:31:55Z EVula 683453 Reverted edits by [[Special:Contributions/Time for action|Time for action]] ([[User talk:Time for action|talk]]) to last version by Plannedobesity '''Mitochondrial Eve''' ('''mt-mrca''') is the name given by researchers to the woman who is defined as the [[matrilineal]] [[most recent common ancestor|most recent common ancestor (MRCA)]] for all [[as of {{CURRENTYEAR}}|currently]] living [[humans]]. Passed down from mother to offspring, her [[mitochondrial DNA]] (mtDNA) is now found in all living humans: every mtDNA in every living person is derived from hers. Mitochondrial Eve is the female counterpart of [[Y-chromosomal Adam]], the [[patrilineal]] most recent common ancestor, although they lived at different times. She is believed to have lived about 140,000 years ago in what is now [[Ethiopia]], [[Kenya]] or [[Tanzania]].{{Fact|date=October 2007}} The time she lived is calculated based on the [[molecular clock]] technique of correlating elapsed time with observed [[genetic drift]]. Mitochondrial Eve is the [[most recent common ancestor|most recent common ancestor (MRCA)]] of all humans ''via the mitochondrial DNA pathway'', not the ''unqualified'' MRCA of all humanity. All living humans can trace their ancestry back to the MRCA via at least one of their parents, but Mitochondrial Eve is defined via the maternal line. Therefore, she necessarily lived at least as long, though likely much longer, ago than the MRCA of all humanity. The existence of Mitochondrial Eve and Y-chromosomal Adam does not imply the existence of [[population bottleneck]]s or a [[first couple]]. They each may have lived within a large human population at a different time. == Matrilineal descent == Mitochondrial Eve is the [[most recent common ancestor]] of all humans ''via the mitochondrial DNA pathway''. In other words, she is the MRCA found when ancestry of all living humans is traced back in time, following only the maternal lineage and disregarding mixed or purely patrilineal descent. The mitochondrial DNA pathway is equivalent to maternal lineage, because [[mitochondrial DNA]] is only passed down from mother to child, never father to child.<ref name="River_Out_of_Eden">See the chapter ''All Africa and her progenies'' in {{cite book | first = Richard | last = Dawkins | authorlink = Richard Dawkins | title = [[River Out of Eden]] | publisher = Basic Books | location = New York | year = 1995 | id = ISBN 0-465-06990-8 }}</ref> To find the Mitochondrial Eve of all living humans, one can start by tracing a line from every individual to his/her mother, then continue those lines from each of those mothers to their mothers and so on, effectively tracing a family tree backward in time based purely on mitochondrial lineages. Going back through time these mitochondrial lineages will converge when two or more women have the same mother. The further back in time one goes, the fewer mitochondrial ancestors of living humans there will be. Eventually only one is left, and this one is the most recent common matrilineal ancestor of all humans alive today, i.e. Mitochondrial Eve. It is possible to draw the same matrilineal tree forward in time by starting with all human female contemporaries of Mitochondrial Eve. Some of these women may have died childless. Others left only male children. For the rest who became mothers with at least one daughter, one can trace a line forward in time connecting them to their daughter(s). As the forward lineages progress in time, more and more lineage lines become extinct, as the last female in a line dies childless or leaves no female children. Eventually, only one single lineage remains, which includes all mothers, and in the next generation, all people, and hence all people alive today. ==Misconceptions== Mitochondrial Eve is the most recent common ''[[Matrilineality|matrilineal]]'' ancestor, not the [[most recent common ancestor]] (MRCA) of all humans. The MRCA's offspring have led to all living humans via sons and daughters, but Mitochondrial Eve must be traced only through female lineages, so she is estimated to have lived much longer ago than the MRCA. While Mitochondrial Eve is thought to have been living around 140,000 years ago, according to probabilistic studies,<ref name="Ancestors_Tale">{{cite book | first = Richard | last = Dawkins | authorlink = Richard Dawkins | title = [[The Ancestor's Tale|The Ancestor's Tale, A Pilgrimage to the Dawn of Life]] | publisher = Houghton Mifflin Company | location = Boston | year = 2004 | id = ISBN 0-618-00583-8 }}</ref> the MRCA could have been living as recently as 3,000 years ago.<ref name="jt_chang_2004">Rohde DLT, Olson S, Chang JT (2004) "[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15457259 Modelling the recent common ancestry of all living humans]". ''Nature'' 431: 562-566.</ref> [[Allan Wilson]]'s naming Mitochondrial Eve<ref name="cann_1987">Cann, R.L., Stoneking, M., and [[Allan Wilson|Wilson, A.C.]], 1987, "Mitochondrial DNA and human evolution", ''Nature'' 325; pp 31&ndash;36. Online: [http://dx.doi.org/10.1038/325031a0 Cann ''et al.'' (1987)]</ref> after [[Adam and Eve|Eve]] of the [[Creation according to Genesis|Genesis creation story]] has led to some misunderstandings among the general public. A common misconception is that Mitochondrial Eve was the only living human female of her time. It is theoretically possible that she was the only human female of her time; however, had she been the only living female of her time, humanity would most likely have become [[extinct]] due to an extreme [[population bottleneck]]. Indeed, not only were many women alive at the same time as Mitochondrial Eve but many of them have descendants alive today. They may have left descendants via either son or daughters (and grandsons or granddaughters, and so on). [[Nuclear gene]]s from these contemporary women of Mitochondrial Eve are present in today's population, but mitochondrial DNA from them is not.<ref name="River_Out_of_Eden"/> What distinguishes Mitochondrial Eve (and her matrilineal ancestors) from all her female contemporaries is that she has a purely matrilineal line of descent to all humans alive today, whereas ''all'' her female contemporaries with descendants alive today have ''at least one male'' in every line of descent. Because mitochondrial DNA is only passed through matrilineal descent, all humans alive today have mitochondrial DNA that is traceable back to Mitochondrial Eve. Furthermore, it can be shown that every female contemporary of Mitochondrial Eve either has no living descendant today or is an ancestor to all living people. Starting with 'the' MRCA at around 3,000 years ago, one can trace all ancestors of the MRCA backward in time. At every ancestral generation, more and more ancestors (via both paternal and maternal lines) of MRCA are found. These ancestors are by definition also common ancestors of all living people. Eventually, there will be a point in past where all humans can be divided into two groups: those who left no descendants today and those who are common ancestors of all living humans today. This point in time is termed the [[identical ancestors point]] and is estimated to be between 5,000 and 15,000 years ago. Since Mitochondrial Eve is estimated to have lived more than hundred thousand years before the identical ancestors point, every woman contemporary to her is either not an ancestor of any living people, or a common ancestor of all living people.<ref name="Ancestors_Tale"/><ref name="jt_chang_2005">Rohde, DLT , ''[http://tedlab.mit.edu/~dr/Papers/Rohde-MRCA-two.pdf On the common ancestors of all living humans]''. Submitted to American Journal of Physical Anthropology. (2005)</ref> == Mitochondrial DNA == {{main|Mitochondrial DNA}} [[Mitochondria]]l [[organelle]]s, which contain [[mitochondrial DNA]] (mtDNA), are passed only from mother to offspring. A comparison of [[DNA sequence]]s from mtDNA in a population reveals a [[molecular phylogeny]]. Unlike mtDNA, which is outside the nucleus, genes containing [[nuclear DNA]] become [[Genetic_recombination|recombined]] after being inherited from both parents, and therefore we can be [[statistic]]ally less certain about nuclear DNA origins than we can for mtDNA, which is only inherited from the mother. mtDNA also mutates at a higher rate compared to nuclear DNA, so it gives researchers a more useful, magnified view of the diversity present in a population.<ref name="wilson_1985">A. C. Wilson, R. L. Cann, S. M. Carr, M. George Jr., U. B. Gyllensten, K. Helm- Bychowski, R. G. Higuchi, S. R. Palumbi, E. M. Prager, R. D. Sage, and M. Stoneking (1985) "Mitochondrial DNA and two perspectives on evolutionary genetics". ''Biological Journal of the Linnean Society'' 26:375-400</ref><ref name="sykes_seven_daughters>[[Bryan Sykes]] <cite>''[[The Seven Daughters of Eve]]: The Science That Reveals Our Genetic Ancestry''</cite>, W.W. Norton, 2001, hardcover, 306 pages, ISBN 0-393-02018-5</ref> Just as mitochondria are inherited matrilineally, [[Y-chromosomes]] are inherited patrilineally.<ref name="sykes_2004">[[Bryan Sykes]] (2004). ''[[Adam's Curse|Adam's Curse. A Future without Men]].'' New York: W. W. Norton.</ref> Thus it is possible to apply the same principles outlined above to men. The common patrilineal ancestor of all humans alive today has been dubbed [[Y-chromosomal Adam]]. Importantly, the genetic evidence suggests that the most recent patriarch of all humanity is much more recent than the most recent matriarch, suggesting that 'Adam' and 'Eve' were not alive at the same time. While 'Eve' is believed to be alive 140,000 years ago, 'Adam' lived only 60,000 years ago.<ref name="Ancestors_Tale"/> ==Eve and the Out-of-Africa theory== Since Mitochondrial Eve is believed to have lived in Africa she is sometimes referred to as '''African Eve''', an ancestor who has been hypothesized on the grounds of [[fossil]] as well as DNA evidence. According to the most common interpretation of the mitochondrial DNA data, the titles belong to the same hypothetical woman. Family trees (or "[[phylogenetics|phylogenies]]") constructed on the basis of mitochondrial DNA comparisons show that the living humans whose mitochondrial lineages branched earliest from the tree ([[Haplogroup L1 (mtDNA)|L1]]) are prevalent among the [[San people|San]] and the [[Mbuti]] people.<ref>[http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1288201 mtDNA Variation in the South African Kung and Khwe]</ref> The subsequent branches of [[Haplogroup L2 (mtDNA)|L2]] and [[Haplogroup L3 (mtDNA)|L3]] are also largely confined to Africa, while only the macrogroups [[Haplogroup M (mtDNA)|M]] and [[Haplogroup N (mtDNA)|N]], descended from L3, participated in the migration out of Africa. Researchers therefore reason that all living humans descend from Africans, some of whom migrated out of Africa and populated the rest of the world. If the mitochondrial analysis is correct, then because mitochondrial Eve represents the root of the mitochondrial family tree, she must have predated the exodus and lived in Africa. Therefore many researchers take the mitochondrial evidence as support for the "[[single-origin hypothesis|single-origin]]" or Out-of-Africa model.<ref name="Ancestors_Tale"/> Some people use the mtDNA family tree as evidence of a [[population bottleneck]] (e.g. [[Toba catastrophe theory]]) giving rise to the human species. There are, however, many ways such family trees can be constructed. A tree can be constructed based on any gene, not just the mitochondrial DNA. When different such trees including the mtDNA tree are compared, no population bottleneck is found because different trees show different [[Coalescent theory|coalescent]] points. The inconsistencies between coalescent points indicate that there had been numerous gene interchanges between population groups around the world, even after the first exodus out of Africa. This idea forms the basis of [[Alan Templeton]]'s 'Out of Africa Again and Again' theory.<ref name="templeton">[http://www.nature.com/nature/journal/v416/n6876/abs/416045a.html Out of Africa Again and Again by Templeton in Nature]</ref><ref name="Ancestors_Tale"/> The Mitochondrial DNA provides another support for the [[Out of Africa hypothesis]] in the form of gene diversity. One finding not subject to interpretation is that the greatest diversity of mitochondrial DNA sequences exists among Africans. This diversity is widely believed to have accumulated because humans have been living longer in Africa than anywhere, although the same relative diversity can also be explained if just ''more'' people lived in Africa than in other regions - an interpretation of the past that all evolutionary models also accept, even those that contradict the African-origin theory, such as [[Multiregional evolution]]. == Academic investigation == Criticisms {{Fact|date=November 2007}} of the original paper by Cann, Stoneking and Wilson<ref name="cann_1987"/> include: *Of the 147 persons sampled, only two were from sub-Saharan Africa. The other 18 'Africans' in the study were black Americans. *The method to generate the tree was not guaranteed to find the most parsimonious tree. *The method used to root the tree placed it at the midpoint of the longest branch (midpoint rooting). This could lead to a wrong position of the root if for example the rate of evolution is higher in Africa. *Restriction-fragment length polymorphism is ill-suited for estimation of mutation rates which is essential in timing evolutionary events. *Weak statistical analysis. Ingman ''et al.'' (2000)<ref name="Ingman_2000">Nature 408, 708-713 (7 December 2000) | doi:10.1038/35047064. Online:[http://dx.doi.org/10.1038/35047064 Ingman ''et al.'' (2000)]</ref> repeated the study while avoiding its major pitfalls: *They sampled 53 persons, 32 of whom were Africans from different regions of sub-Saharan Africa. *They sequenced the complete mtDNA but excluded the rapidly evolving [[D-loop]] in the analysis. *An outgroup ([[chimpanzee]]) mtDNA sequence was used to root the tree (outgroup rooting). Outgroup rooting is much more reliable than midpoint rooting. The study by Ingman ''et al.'' verifies the major conclusions of Cann ''et al.'' of an African origin of human mtDNA within the past 172 000 ± 50 000 years. == In popular culture == *[[Bryan Sykes]] has written a [[popular science]] book entitled ''[[The Seven Daughters of Eve]]''. *In ''[[River Out of Eden]]'', [[Richard Dawkins]] discusses human ancestry in the context of a river of genes and shows that Mitochondrial Eve is one of the many common ancestors we can trace back to via different gene pathways. *The [[Discovery Channel]] produced a [[Documentary film|documentary]] entitled ''[[The Real Eve]]'', based on the book ''Out of Eden'' by [[Stephen Oppenheimer]]. *The [[Japan]]ese [[novel]], [[horror film]] and [[video game]] series ''[[Parasite Eve]]'' uses the Mitochondrial Eve theory as the basis for a fantasy about a scientist resurrecting his wife by [[regeneration (biology)|regenerating]] her liver cells, with disastrous effects. *[[Greg Egan]] has written a short story called "Mitochondrial Eve". *The [[anime]]/[[manga]] series ''[[K.R.I.E.G]]'' made several references to mitochondria and the existence of the Mitochondrial Eve theory, among many other theories of evolution and human creation. *[[Arthur C. Clarke]] and [[Stephen Baxter]]'s novel ''[[The Light of Other Days]]'' describes a sequence where mitochondrial DNA is visually traced back to a Mitochondrial Eve. *The [[manga]] series ''[[Elfen Lied]]'' also mentions Mitochondrial Eve, with the suggestion of creating a new race, with a new Mitochondrial Eve. ==See also== {| |-valign="top" | * [[Coalescent theory]] * [[Genealogical DNA test]] * [[Genetic genealogy]] * [[Haplogroup L1 (mtDNA)]] * [[Human evolution]] * [[Human mitochondrial DNA haplogroups]] * [[Last universal ancestor]] | * [[Mitochondrial genome]] * [[Most recent common ancestor]] * [[Neutral theory of molecular evolution]] * [[Single origin hypothesis]] * [[Timeline of evolution]] * [[Timeline of human evolution]] * [[Y-chromosomal Aaron]] * [[Y-chromosomal Adam]] |} == References == {{reflist}} {{refbegin}} *Excoffier, L., and Yang, Z., "Substitution Rate Variation Among Sites in Mitochondrial Hypervariable Region I of Humans and Chimpanzees", 1999, ''Mol. Biol. Evol.'' 16; pp 1357&ndash;1368 * Kaessmann, H., and Pääbo, S.: "The genetical history of humans and the great apes". ''Journal of Internal Medicine'' 251: 1&ndash;18 (2002). [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11851860&dopt=Abstract pubmed] * Laurence Loewe and Siegfried Scherer, “Mitochondrial Eve: The Plot Thickens,” Trends in Ecology & Evolution, Vol. 12, [[11 November]] 1997, p. 422. * Nicole Maca-Meyer , Ana M González , José M Larruga, Carlos Flores and Vicente M Cabrera (2001) "Major genomic mitochondrial lineages delineate early human expansions". BMC Genetics [http://www.biomedcentral.com/1471-2156/2/13 Biomed central] *Oppenheimer, Stephen. The Real Eve, Carroll & Graf; (September 9, 2004) ISBN 0-7867-1334-8 *Vigilant, L., Pennington, R., Harpending, H., Kocher, T.D., Wilson, A.C., 1989, "Mitochondrial DNA Sequences in Single Hairs from a Southern African Population", ''Proc. Natl. Acad. Sci. USA'' 86; pp 9350-9354 * Thomas J. Parsons et al., “A High Observed Substitution Rate in the Human Mitochondrial DNA Control Region,” Nature Genetics, Vol. [[15 April]] 1997, p. 365. *Vigilant, L., Stoneking, M., Harpending, H., Hawkes, K., Wilson, A.C., 1991, "African Populations and the Evolution of the Human Mitochondrial DNA", ''Science'' 253; pp 1503&ndash;1507 [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1840702&dopt=Citation Pubmed] * Watson E., Forster P., Richards M., Bandelt H.-J. (1997). "Mitochondrial Footprints of Human Expansions in Africa." ''American Journal of Human Genetics''. 61: 691-704 [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9326335&dopt=Citation pubmed] * Spencer Wells <cite>''The Journey of Man: A Genetic Odyssey''</cite>, Princeton University Press, January 2003, hardcover, 246 pages, ISBN 0-691-11532-X {{refend}} == External links == {{Spoken Wikipedia|Mitochondrial Eve.ogg|2005-04-22|SubCat=}} * [http://www.talkorigins.org/faqs/homs/mitoeve.html Krishna Kunchithapadam, "What if anything is a Mitochondrial Eve?"]: a simple explanation * [http://www.chartsgraphsdiagrams.com/evolution/mitochondrial-eve.html Mitochondrial Eve and Y-chromosomal Adam Diagrams] {{MtDNA}} [[Category:Biology timelines|Mitochondrial Eve]] [[Category:DNA]] [[Category:Evolution]] [[Category:Evolutionary biology]] [[Category:Genetic genealogy]] [[Category:Genealogy]] [[Category:Human evolution]] [[Category:Human mtDNA haplogroups]] [[Category:phylogenetics]] [[Category:Recent single origin hypothesis]] [[Category: Mitochondrial genetics]] [[Category:Prehistoric Africa]] [[ca:Eva mitocondrial]] [[cs:Poslední společný předek (mtDNA)]] [[da:Mitokondrielle Eva]] [[de:Mitochondriale Eva]] [[es:Eva mitocondrial]] [[fr:Ève mitochondriale]] [[gl:Eva mitocondrial]] [[it:Eva mitocondriale]] [[hu:Mitokondriális Éva]] [[nl:Mitochondriale Eva]] [[ja:ミトコンドリア・イブ]] [[pl:Mitochondrialna Ewa]] [[pt:Eva mitocondrial]] [[fi:Mitokondrio-Eeva]] [[sv:Mitokondrisk Eva]] [[zh:粒線體夏娃]]