Y-haplogroup A
Y-chromosome haplogroup A is considered as the deepest-rooting clade of the Y phylogeny. It is regarded as African-specific.
References
King TE, Parkin EJ, Swinfield G, Cruciani F, Scozzari R, Rosa A, Lim SK, Xue Y, Tyler-Smith C, Jobling MA. Africans in Yorkshire? The deepest-rooting clade of the Y phylogeny within an English genealogy. Eur J Hum Genet. 2007 Mar;15(3):288-93. PMID: 17245408