All modern humans descend in the male line from a particular man, nicknamed “Genetic Adam,” who lived about 60,000 years ago. All living men have inherited his y chromosome (yDNA), along with the mutations that have accumulated in our individual family lines.
Geneticists can test for these accumulated mutations. Individual test results show a man’s haplotype. Groups of similar haplotypes form a haplogroup.
Technically, a haplogroup consists of all the male-line descendants of an ancestor who had a particular SNP mutation in his y chromosome. Geneticists currently recognize 18 haplogroups, each designated with a capital letter between A and R. In addition, subgroups within each haplogroup are represented by numbers and further subgroups by letters. For example, G, G1, G1a and G1b, where G is the haplogroup, 1 is a subgroup, and a and b are further subgroups. G* represents a man who belongs to haplogroup G but not to one of the defined subgroups.
Haplogroups are genetic groups that share a distant male ancestor who lived before the adoption of surnames. They are identified by particular mutations that the founding ancestor passed on to all his descendants in the male line.
Humans exhibit less mtDNA and yDNA diversity than expected, far less than our closest primate cousins, the chimpanzees. Some scientists believe that humans nearly became extinct about 70,000 years ago (~2,800 generations) when the Toba supervolcano erupted in Indonesia, triggering an environmental catastrophe. According to this theory, the human population might have been reduced to a few thousand people, perhaps as few as 1,000.
An article in Science magazine (2000) estimated that 80% of European men share a common ancestor, who lived as a primitive hunter some 40,000 years ago. He was one of the Paleolithic (Old Stone Age) people who first migrated to Europe, probably from Central Asia and the Middle East, in two waves of migration beginning about 40,000 years ago. Their numbers were small and they lived by hunting animals and gathering plant food. They used crudely sharpened stones and fire.
When the last ice age began, about 24,000 years ago, the Paleolithic Europeans retreated to Spain, the Balkans and the Ukraine, where they lived for hundreds of generations. When the glaciers melted, about 16,000 years ago, these three groups spread out through Europe. The male-line descendants of the group that lived in Spain are now most common in northwest Europe, those from the Ukraine are primarily in Eastern Europe, and those from the Balkans are most common in Central Europe.
During the Neolithic (New Stone Age) era, about 8,000 years ago, another wave of migration, this time from the Middle East, brought agriculture to Europe. About 20 percent of modern Europeans have a y chromosome that shows they descend from this Neolithic migration.
Unlike mtDNA, yDNA haplogroup dispersal is “highly non-random”. That is, yDNA haplogroups are concentrated in certain geographic areas, even though there is no area where the entire population belongs to the same haplogroup. Therefore, geneticists can use modern haplogroup dispersal to trace population movements in pre-historic time.
Haplogroup B: This lineage is one of the oldest y-chromosome lineages in humans. It s found exclusively in Africa. This lineage was the first to disperse around Africa. Archaeological evidence suggests a major population expansion in Africa approximately 90-130,000 years ago. It has been suggested that this event might have spread Haplogroup B throughout Africa. Haplogroup B appears at low frequency all over Africa, but is at its highest frequency in Pygmy populations.
Haplogroup C: This lineage originated about 50,000 years ago, shortly after humans left Africa. It is found throughout mainland Asia and the south Pacific, and at low frequency in Native American populations. This lineage colonized New Guinea, Australia, and northern Asia. It is currently found with its highest diversity in populations of India. Genghis Khan seems to have been a member of this haplogroup. The C3 subgroup is believed to have originated in southeast or central Asia. It spread into northern Asia, then into the Americas.
Haplogroup D: This lineage probably originated in Japan. It is completely restricted to Japan, and is a very diverse lineage among the aboriginal Japanese and the Japanese population around Okinawa.
Haplogroup E: This lineage probably originated in northeastern Africa based on the concentration and variety of E subclades in that area today. But the fact that Haplogroup E is closely linked with Haplogroup D, which is not found in Africa, leaves open the possibility that E first arose in the Near or Middle East and was carried into Africa by a back migration. E1b1a is the most common lineage among African Americans. E1b1b1 probably evolved either in northeastern Africa or the Near East and then expanded to the west, both north and south of the Mediterranean Sea. E1b1b1 clusters are seen today in western Europe, southeasten Europe, the Near East, northeastern Africa and northwestern Africa. William Harvey, who discovered the principle of blood circulation belonged to E1b1b1, as Wilbur and Orville Wright. The Polish Haurys are E1b1b1.
Haplogroup G: This lineage probably originated in Anatolia (Asia Minor). It has dispersed into central Asia, Europe, and the Middle East. It is most common in the Caucasus region, especially the Republic of Georgia where it approaches 30% of the population. In Turkey it is found in some 10% of the population. The G2 branch of this lineage is found most often in Europe and the Middle East. In Europe, haplogroup G accounts for 1-2% of the population with a gradient from southeast (most common) to northwest (least common). Haplogroup G, along with Haplogroups J and E3b, is thought to be a marker for the spread of farmers from the Middle East into Europe 6,000-8,000 years ago. In Italy, it accounts for some 10% of population, and is especially concentrated in Lombardy. It diffuses north into Switzerland and Germany, with another concentration in the Austrian Tirol. In Scandinavia, it accounts for only 1-3% of the population. Russian dictator Joseph Stalin belonged to haplogroup G2a1. The Swiss Hauris belong to haplogroup G2a4.
Haplogroup H: This lineage is believed to have originated in India between 20,000 and 30,000 years ago. It seems to represent the indigenous paleolithic inhabitants of India, because it is the most frequent among tribal populations, but rare among the higher castes. This haplogroup is almost completely restricted to India, Sri Lanka and Pakistan. It is also common among the Roma (Gypsies).
Haplogroup I: This lineage is almost entirely confined to Europe, where it accounts for about 20% of the population. Semino et al. believe that Haplogroup I stems from the Gravettian culture, which arrived in Europe from the Middle East about 20-25,000 years ago. The Gravettian culture was “known for its Venus figurines, shell jewelery, and for using mammoth bones to build homes.” There are two main branches of Haplgroup I:
- Haplogroup I1: This lineage has highest frequency in Scandinavia, Iceland, and northwest Europe. One lineage of this group extends down into central Europe, probably as a result of the barbarian invasions during the late Roman Empire. There are smaller concentrations on the coasts of northwestern Europe. Haplogroup I1 has been called the Viking group. Its distribution along the coasts of northwestern Europe probably reflects Viking raids and settlements in the 8th and 9th centuries.
- Haplogroup I2: appears to have originated in the Balkans, perhaps from a glacial refugium there; I2a is very common in Croatia and Bosnia today and decreases in frequency across Eastern Europe. A rare offshoot branch of I2a is also found further West, including in the British Isles. Another subgroup of I2a is by far the most common lineage in Sardinia, but it is also found at low frequencies in France and Spain. A Howery family of unknown origin belongs to I2a.
Haplogroup J: This lineage is found at highest frequencies in Middle Eastern and north African populations, where it probably evolved. This marker has been carried by Middle Eastern traders into Europe, central Asia, India and Pakistan.
- Haplogroup J2: This lineage originated in the northern part of the Fertile Crescent. It later spread throughout central Asia and the Mediterranean, and south into India. As with other populations with Mediterranean ancestry, this lineage is found within Jewish populations.
Haplogroup K: his lineage first appeared about 40,000 years ago in Iran or southern central Asia.
Haplogroup N: This lineage is distributed throughout northern Eurasia. It is the most common y chromosome type among Uralic speakers (Finns and Hungarians). This lineage probably originated in northern China or Mongolia, then spread into Siberia where it became a very common line in western Siberia.
- Haplogroup N3: One study in Hungary found that 12% of the male population today belongs to this haplogroup. It is found most in the region of Asia where the Huns are supposed to have originated, and where the language is still similar to theirs. The Huns invaded Europe in historic times. The other 88% of Hungarians descend mainly from the inhabitants of the former Roman province of Pannonia, which, once conquered, took on the new language.
Haplogroup O1: This lineage is found at very high frequency among the aboriginal Taiwanese (possibly due to genetic drift). It probably originated in eastern Asia and later migrated into the south Pacific. Individuals carrying this lineage are thought to have been important in the expansion of the Austronesian language group into Taiwan, Indonesia, Melanesia, Micronesia and Polynesia.
Haplogroup Q: This lineage is found in Asia and the Americas. It is found in north and central Asian populations as well as native Americans. This lineage is believed to have originated in central Asia and migrated through the Altai/Baikal region of northern Eurasia into the Americas.
- Haplogroup Q3: This lineage is the only lineage strictly associated with indigenous American populations. The mutation that defines it occurred in the Q lineage 8-12,000 years ago as the migration into the Americas was underway. There is some debate about the side of the Bering Strait on which this mutation occurred, but it definitely happened among the ancestors of the Native American people.
- Haplogroup R1a: This lineage is believed to have originated in the Eurasian steppes north of the Black and Caspian Seas, perhaps in a population of the Kurgan culture. The Kurgans were known for the domestication of the horse (approximately 3000 BCE). They are believed to have been the first speakers of an Indo-European language. This lineage is currently found in central and western Asia, in India, and in the Slavic populations of eastern Europe. Somerled, who defeated the vikings and established a kingdom in the Hebrides, was a member of this haplogroup.
- Haplogroup R1b: This lineage is the most common haplogroup in European populations. It is found in about 90% of Basques, 80% of Irish and Welsh, 70% of Scots, 60% of English, 50% of French, 50% of Germans, but only 25% of Norwegians and 1% of Syrians. It is believed to represent the main pre-Ice Age population of western Europe, which expanded throughout Europe as humans re-colonized after the last Ice Age 10-12,000 years ago. Studies on Scottish and Irish families have shown that Colla Uais and Niall of the Nine Hostages, the putative ancestors of many clans and septs, were probably members of this haplogroup.
Haplogroup T: Thomas Jefferson was a member of this lineage. Descendants of his paternal uncle Field Jefferson were tested as part of a project to verify the paternity of the children of Thomas Jefferson’s mistress, Sally Hemmings.
As a general rule: R1b = Western Europe, R1a = Eastern Europe, I = Nordic, G = Indo-Aryan, J2 & E3b = Semitic, and Q3 = Native American.