Most recent common ancestor

A most recent common ancestor (MRCA), also known as a last common ancestor (LCA), is the most recent individual from which all organisms of a set are inferred to have <a href="/facts/Common_descent/bwEgMu7F">descended</a>. The most recent common ancestor of a higher taxon is generally assumed to have been a <a href="/facts/Species/oDg6b96r">species</a>. The term is also used in reference to the ancestry of groups of <a href="/facts/Gene/e1swwPY6">genes</a> (<a href="/facts/Haplotype/0W2SEdu4">haplotypes</a>) rather than organisms.
The ancestry of a set of individuals can sometimes be determined by referring to an established <a href="/facts/Pedigree_chart/smI3Q7Bq">pedigree</a>, although this may refer only to patrilineal or matrilineal lines for sexually-reproducing organisms with two parents, four grandparents, etc. However, in general, it is impossible to identify the exact MRCA of a large set of individuals, but an estimate of the time at which the MRCA lived can often be given. Such time to most recent common ancestor (TMRCA) estimates can be given based on DNA test results and established <a href="/facts/Mutation_rate/4Y2pGIMJ">mutation rates</a> as practiced in genetic genealogy, or by reference to a non-genetic, <a href="/facts/Mathematical_model/CGhyuxgz">mathematical model</a> or computer simulation.
In organisms using <a href="/facts/Sexual_reproduction/hmsXy53s">sexual reproduction</a>, the matrilineal MRCA and patrilineal MRCA are the MRCAs of a given population considering only <a href="/facts/Matrilineal/RFgpp4Bg">matrilineal</a> and <a href="/facts/Patrilineal/DRID1Ly4">patrilineal</a> descent, respectively. The MRCA of a population by definition cannot be older than either its matrilineal or its patrilineal MRCA. In the case of <a href="/facts/Homo_sapiens/rlcTENsr">Homo sapiens</a>, the matrilineal and patrilineal MRCA are also known as "<a href="/facts/Mitochondrial_Eve/Rqe4l07E">Mitochondrial Eve</a>" (mt-MRCA) and "<a href="/facts/Y-chromosomal_Adam/7eadQ7ml">Y-chromosomal Adam</a>" (Y-MRCA) respectively. The age of the human MRCA is unknown. It is no greater than the age of either the Y-MRCA or the mt-MRCA, estimated at 200,000 years.
Unlike in pedigrees of individual humans or domesticated lineages where historical parentage is known for some number of generations into the past, ancestors are not directly observable or recognizable in the inference of relationships among species or higher groups of <a href="/facts/Taxa/caQC1e87">taxa</a> (<a href="/facts/Systematics/fagPXIkh">systematics</a> or <a href="/facts/Phylogenetics/bw4rsovt">phylogenetics</a>). Ancestors are inferences based on patterns of relationship among taxa inferred in a <a href="/facts/Phylogenetic_analysis/bw4rsovt">phylogenetic analysis</a> of extant organisms and/or <a href="/facts/Fossils/by7NzIA1">fossils</a>.
The <a href="/facts/Last_universal_common_ancestor/pnpExNAU">last universal common ancestor</a> (LUCA) is the most recent common ancestor of all current life on Earth, estimated to have lived some 3.5 to 3.8 billion years ago (in the <a href="/facts/Paleoarchean/5cldXjwo">Paleoarchean</a>).

Most recent common ancestor open-in-new

Most recent common ancestor