Most recent common ancestor

Such time to most recent common ancestor (TMRCA) estimates can be given based on DNA test results and established mutation rates as practiced in genetic genealogy, or by reference to a non-genetic, mathematical model or computer simulation.

In the case of Homo sapiens, the matrilineal and patrilineal MRCA are also known as "Mitochondrial Eve" (mt-MRCA) and "Y-chromosomal Adam" (Y-MRCA) respectively.

Unlike in pedigrees of individual humans or domesticated lineages where historical parentage is known, in the inference of relationships among species or higher groups of taxa (systematics or phylogenetics), ancestors are not directly observable or recognizable.

[2][3][note 1] The project of a complete description of the phylogenetic relationships among all biological species is dubbed the "tree of life".

Coalescent theory describes a stochastic model of how the ancestry of such genetic markers maps to the history of a population.

It can be used to trace patrilineal inheritance and to find the Y-chromosomal Adam, the most recent common ancestor of all humans via the Y-DNA pathway.

A paper published in March 2013 determined that, with 95% confidence and that provided there are no systematic errors in the study's data, Y-chromosomal Adam lived between 237,000 and 581,000 years ago.

Patrilineal and matrilineal MRCAs (Mitochondrial Eve and Y-chromosomal Adam) are traced by single gene markers, thus their TMRCA are computed based on DNA test results and established mutation rates as practiced in genetic genealogy.

The latter considers only individual humans, without taking into account whether any gene from the computed MRCA actually survives in every single person in the current population.

The tree is formed through the testing of a large number of individuals all over the world for the presence or lack of a certain set of mutations.

In this case the variability of the Y-STR sequence, also called the microsatellite variation, can be regarded as a measure of the time passed since the ancestor founded this particular population.

[12] TMRCA calculations are considered critical evidence when attempting to determine migration dates of various populations as they spread around the world.

It concludes that the MRCA of all humans probably lived in East Asia, which would have given them key access to extremely isolated populations in Australia and the Americas.

European colonization of the Americas and Australia was found by Chang to be too recent to have had a substantial impact on the age of the MRCA.

It rather reflects the presence of a single individual with high reproductive success in the past, whose genetic contribution has become pervasive throughout the population over time.

Euryarchaeota Nanoarchaeota Thermoproteota Protozoa Algae Plant Slime molds Animal Fungus Gram-positive bacteria Chlamydiota Chloroflexota Actinomycetota Planctomycetota Spirochaetota Fusobacteriota Cyanobacteria Thermophiles Acidobacteriota Pseudomonadota
Evolutionary tree showing the divergence of modern species from the last universal ancestor in the center. [ 5 ] The three domains are colored, with bacteria blue, archaea green, and eukaryotes red.
Through random drift or selection, lineage will trace back to a single person. In this example over 5 generations, the colors represent extinct matrilineal lines and black the matrilineal line descended from the mt-MRCA.