This point lies further in the past than the population's most recent common ancestor (MRCA).
Eventually the point is reached where all people in the past population fall into one of two categories: they are common ancestors, with at least one line of descent to everyone living today, or they are the ancestors of no one alive today, because their lines of descent are completely extinct on every branch.
[2] In 2004, Rohde, Olson and Chang showed through simulations that, given the false assumption of random mate choice without geographic barriers, the Identical Ancestors Point for all humans would be surprisingly recent, on the order of 5,000-15,000 years ago.
[3][4][further explanation needed] More recently, however, researchers have estimated the European isopoint to be closer to 1000 A.D.[5] All living people share exactly the same set of ancestors before the Identical Ancestors Point, all the way to the very first single-celled organism.
[3] However, people will vary widely in how much ancestry and genes they inherit from each ancestor, which will cause them to have very different genotypes and phenotypes.
This is illustrated in the 2003 simulation as follows: considering the ancestral populations alive at 5000 BC, close to the ACA point, a modern-day Japanese person will get 88.4% of their ancestry from Japan, and most of the remainder from China or Korea, with only 0.00049% traced to Norway; conversely, a modern-day Norwegian will get over 92% of their ancestry from Norway (or over 96% from Scandinavia) and only 0.00044% from Japan.