Haplogroup J is believed to have arisen 31,700 years ago (plus or minus 12,800 years) in the Near East (Semino et al. 2004). It is most closely related to Haplogroup I, as both Haplogroup I and Haplogroup J are descendants of Haplogroup IJ (S2, S22). Along with haplogroups G, H and K, haplogroup IJ is in turn derived from Haplogroup F. The main current subgroups J1 and J2, which now account between them for almost all of the population of the haplogroup, are both believed to have arisen very early, at least 10,000 years ago.
Haplogroup J is found in greatest concentration in the Caucasus and Southwest Asia. Outside of these regions, haplogroup J has a moderate presence in Southern Europe (especially in central and southern Italy, Greece, and Albania), Central Asia, and South Asia, particularly in the form of its subclade J2-M172. Haplogroup J is also found in North Africa and the Horn of Africa, particularly in the form of its subclade J1-M267. Subclades J2a and J2a1b1 are found mostly in Greece, Anatolia, and southern Italy.
J1 is generally frequent amongst Arabs of the southern Levant, i.e. Palestinian Arabs (38.4%) (Semino et al.) and Arab Bedouins (62% and 82% in Negev desert Bedouins). It is also very common among other Arabic-speaking populations, such as those of Algeria (35%), Syria (30%), Iraq (33%), the Sinai Peninsula, and the Arabian Peninsula. The frequency of Haplogroup J1 collapses suddenly at the borders of Arabic countries with mainly non-Arabic countries, such as Turkey and Iran, yet it is found at low frequency among the populations of those countries, as well as in Cyprus, Sicily and the Iberian Peninsula. It entered Ethiopia with the spread of Semitic speakers (11% Eritrea & 9 % Ethiopia & Ethiopia-Amhara 33.3%). It spread later to North Africa in historic times (as identified by the motif YCAIIa22-YCAIIb22; Algerians 35.0%, Tunisians 30.1%), where it became something like a marker of the Arab expansion in the early medieval period (Semino et al. 2004). Researchers believe that marker DYS388=17 (Y DNA tests for STR - Short Tandem Repeater) is linked with the later expansion of Arabian tribes in the southern Levant and northern Africa (Di Giacomo et al. 2004).
Haplogroup J1 is found almost exclusively among modern populations of the Southwest Asia, North Africa, and the Horn of Africa, essentially delineating the region popularly known as the Middle East and associated with speakers of Semitic languages and Northeast Caucasian languages. The distribution of J1 outside of the Middle East may be associated with Arabs and Phoenicians who traded and conquered in Sicily, southern Italy, Spain, Azerbaijan, Turkey, and Pakistan, or with Jews, who have historical origins in the Middle East and speak (or historically spoke) a Semitic language, though typically Haplogroup J2 is more than twice as common among Jews. In Jewish populations overall, J1 constitutes 19.0% of the Ashkenazim results and 11.9% of the Sephardic results (Semino et al. 2004)(Behar et al. 2004). Haplogroup J1 with marker DYS388=13 is a distinctive type found in eastern Anatolia (Cinnioglu et al. 2004).
Haplogroup J2 is thought to have originated in Anatolia (Turkey) or northern Mesopotamia and to have subsequently spread to other Middle Eastern areas, Europe, Central Asia, and South Asia. Subclades of Haplogroup J2 are commonly found in Turkey, the Levant, Mesopotamia, the South Caucasus (Georgia, Armenia, Azerbaijan), Iran, Central Asia, and South Asia: for example, Muslim Kurds (28.4%), Central Turks (27.9%), Georgians (26.7%), Iraqis (25.2%), Lebanese (25%), Saudi Arabians (18.9%), Ashkenazi Jews (23.2%), Sephardi Jews (28.6%), Iranians (23.3%), Tajiks (18.4%), and Pakistanis (14.7%). Haplogroup J2 is also common among Turkic peoples of the North Caucasus, such as Balkars (25%) and Kumyks (25%). J2 is not regularly found in Semitic-speaking populations of Africa, such as the Amhara and Tigrinya in Eritrea and Ethiopia (Semino et al. 2004). However, J2 has been found to encompass several subhaplogroups (22 subhaplogroups, including 5 that have high frequencies) that originated in or expanded into different regions: the Iberian Peninsula, Italy, the Balkans, the Aegean, Anatolia (Turkey and Kurds), the Caucasus (Georgia). Haplogroup J2 used to be considered a genetic marker of Anatolian Neolithic agriculturalists. It is also very frequent in the Balkans (Greeks 20.6%, Albanians 19.6%) and in Iberia (16.7-29.1%). Its frequency rapidly drops in the Carpathian basin (Ukrainians 7.3%, Croatians 6.2%, Romanians 5.6%, Hungarians 2.0%) and in Southeastern Iranian-speaking areas (Pashtuns 5.2%, Pamiris 6.1%). A significant presence of J2 (J2b2+J2a) was detected in western and south-western India (the highest being 21% among Dravidian middle castes, followed by upper castes, 18.6%, and lower castes 14%; Sengupta et al. 2006).
There are also some haplogroup J Y-chromosomes that belong to neither J1 nor J2, and are said to be in paragroup J*(xJ1,J2). This means that haplogroup J* includes all of J except for J1 and J2. However, Y-chromosomes that belong to paragroup J* are extremely rare among human populations of the present day.