Haplogroup A-P305 also known as A1 is a human Y-chromosome DNA haplogroup. Like its parent haplogroup haplogroup A0-T (A-L1085), A1 includes the vast majority of living human males. It emerged in Africa approximately 161,300 years ago. ^[1] By comparison, members of its sole sibling subclade, haplogroup A0 – the only other primary subclade of haplogroup A0-T – are found mostly in Africa.

Basal, undivergent A-P305* is largely restricted to populations native to Africa, though a handful of cases have been reported in Europe and Western Asia. A-P305* is found at its highest rates in Bakola Pygmies (South Cameroon) at 8.3% and Berbers from Tunisia at 1.5%^[2] and in Ghana.^[3] The clade also achieves high frequencies in the Bushmen hunter-gatherer populations of Southern Africa, followed closely by many Nilotic groups in Eastern Africa. However, haplogroup A's oldest sub-clades are exclusively found in Central-Northwest Africa, where it, and consequently Y-chromosomal Adam, is believed to have originated about 140,000 years ago.^[2] The clade has also been observed at notable frequencies in certain populations in Ethiopia, as well as some Pygmy groups in Central Africa.