Last Common Ancestor

Last Common Ancestor (LCA) is the of two populations that came to be separated by a.

LCA of two species


The more distantly related two species are, the more ancient their LCA will be. The LCA of elephant and earthworm, for example, lived an ancient two billion years ago. The LCA of two more similar species, the elephant and the, lived three hundred million years ago, while the LCA of the elephant and , two closely related species, lived only seven million years ago.

Other common ancestor titles
 (LUA) or Last Universal Common Ancestor (LUCA), or either name without the "Last", are the names given to the hypothetical and controversial organism or single  that gave rise to all  three to four billion years ago.



Concestor: Term coined by Richard Dawkins as a possible replacement for "Last Common Ancestor."

Common ancestor: Any two species have millions of plain “common ancestors”. The ancestors of the elephant and mammoth, for example, were common to both species for billions of years &mdash; up to their split seven million years ago, this being the date of their last common ancestor.

The term "common ancestor" is often used in a sense, which is different from the species sense discussed here. You and your cousin have three grandfathers between you, one of whom is a "common" grandfather. You share a great grandfather with your second cousins, and share a great great great great great grandfather with perhaps a thousand of your 6th cousins. It has been estimated that is a common grandfather to some 16 million men.

“Most Recent” Common Ancestor: Until 1999 the terms “Last” and “Most recent” common ancestor had been used more or less interchangeably. In papers published since then, however (Rohde, Olson, and Chang; see reference, below), the term MRCA has come to mean a particular ancestor within a species &mdash; for example, a common grandfather &mdash; rather than the species’ founder. Computer simulations suggest that every person living today could share a common ancestor who lived as few as 2,000 years ago. This person (name lost to history) has been entitled the Most Recent Common Ancestor (MRCA) of All Mankind.