Most recent common ancestor
From Biocrawler, the free encyclopedia.
The most recent common ancestor (MRCA) of any set of organisms is the most recent individual which is an ancestor of all of them. The term is most frequently used of humans. A recent article by Douglas Rohde, Steve Olson, and Joseph Chang, "Recent Common Ancestors of All Present-Day Individuals" suggests that the MRCA of all humans now living was a human within historical times (3000 BC - AD 1000), while other studies suggest the MRCA of those living in Western civilizations is as recent as AD 1000. The same article provides surprisingly recent estimates for the identical ancestors point, the most recent time when each person was an ancestor to all or ancestor to none of the people alive today.
The "most recent common ancestor" accounts for lines of descent including both sexes; comparable notions such as Mitochondrial Eve and Y-chromosomal Adam account for either a purely matrilineal line or a purely patrilineal line, traceable through only uniparental inheritance (mitochondrial DNA for matrilineal inheritance or Y-chromosome-DNA for patrilineal inheritance), and so yield common ancestors that are more ancient. (Hartwell 2004:539)
It is possible to use established mutation rates as a basis for calculating an estimate of the time since the most recent common paternal ancestor of any two individuals for which Y-chromosomal haplotyping has been performed, or for the time elapsed since the most recent common maternal ancestor of any two individuals for which mt-DNA typing information is available. It is not possible as of 2004 to similarly estimate the time-frame for an actual most recent common ancestor, largely because of the many variables introduced by recombination.
References
- Genetics: From Genes to Genomes by Leland Hartwell et al (2004).
See also
- Identical ancestors point -- (link (http://www.nature.com/news/2004/040927/pf/040927-10_pf.html) explaining the relationship of "most recent common ancestor" and "identical ancestors point.")
- Mitochondrial Eve
- Y-chromosomal Adam
- Genetic genealogy
- Genealogy
External links
- DNA Heritage - Understanding MRCA for genetic genealogy (http://www.dnaheritage.com/statistics.asp)
- Family Tree DNA - Understanding MRCA (http://www.familytreedna.com/faq2.html)
- Nature - 30 September 2004 - Modelling the recent common ancestry of all living humans (http://www.nature.com/doifinder/10.1038%2Fnature02842)
- Joseph T. Chang's "Recent Common Ancestor of All Present-Day Individuals" (.pdf file) (http://www.stat.yale.edu/~jtc5/pubs/Ancestors.pdf)
- Paper on estimating MRCA from Y-chromosomal or mt-DNA data (http://www.genetics.org/cgi/content/full/158/2/897#ABSTRACT)
- link to a downloadable MRCA calculator (".exe" file) (http://archiver.rootsweb.com/th/read/GENEALOGY-DNA/2001-12/1008355259)
- Science Daily: 'Most Recent Common Ancestor' Of All Living Humans Surprisingly Recent (http://www.sciencedaily.com/releases/2004/09/040930122428.htm)
