Y-chromosomal Adam - Variable Adam

Variable Adam

The title "Y-chromosomal Adam" is not permanently fixed on a single individual. Because knowledge of human Y chromosomes is still incomplete, Y-chromosomal Adam's DNA sequence, his position in the family tree, the time when lived, and his place of origin, are all subject to future revisions. In addition, demographic changes during the course of human evolution would have frequently caused the title of Y-chromosomal Adam to change hands. The following events would change the individual designated Y-chromosomal Adam:

• Further sampling of Y chromosomes could uncover previously unknown divergent lineages. If this happens, Y-chromosome lineages would converge on an individual who lived further back in time.
• The discovery of additional deep rooting mutations in known lineages could lead to a rearrangement of the family tree.
• When deep rooting haplogroups are permanently lost from the world's population, living human Y chromosomes converge on a more recent common ancestor. A Y-chromosome lineage is halted when a male dies without leaving any male offspring (although this individual may or may not have had daughters). Phenomena such as bottlenecks and genetic drift during human evolution would have caused the total extinction of several basal haplogroups. Because of these factors, the title "Y-chromosomal Adam" has changed hands numerous times.