Thursday, November 3, 2011

My MtDNA - Haplogroup L2a

IntroductionL2 is the most common haplogroup among both Africans and African Americans. It arose about 95,000 years ago, but did not reach its predominance in Africa until much more recently, when Bantu-speaking populations began moving east and south from the vicinity of present-day Cameroon. That migration, which began about 4,000 years ago and lasted into historical times, reshaped the continent's genetic landscape by dramatically expanding the range of L2 and other western African haplogroups. L2a, which dates back about 55,000 years, is present in 20% or more of both Africans and African Americans.

L2 is found among African Americans whose ancestors were transported from West African slave centers.

L2a and the Bantu ExpansionHaplogroup L2a is extremely common among the vast majority of Africa south of the Sahara. In f`act, it is so widespread and diverse that it has been difficult to pinpoint where in Africa it arose. However, current thinking puts the origins of L2a somewhere in Central Africa. At the peak of the Last Ice Age 20,000 years ago, when the Sahara Desert became entirely uninhabitable and began expanding to the south, people bearing Haplogroup L2a began journeying in two directions: east toward the cooler climate of the eastern highlands, and west towards the Atlantic coast.But this ancient expansion was not to be the last in the history of L2a. Beginning about 4,000 years ago, two sub-branches of L2a — L2a1a and L2a1b — were swept up with the Bantu-speaking people of West Africa. These people, who had been practicing farming for a millennium or more, began to expand their territory and gradually introduced both their language and their way of life to their eastern and southern neighbors. Today, both L2a1a and L2a1b are well-represented in Southeast Africa, and L2a reaches levels of 36% in the southeastern African nation of Mozambique.While for the most part the barrier of the Sahara Desert prevented L2a from expanded into North Africa, the haplogroup has been found in about 4% of Tunisians. This suggests that at least a few people bearing L2a managed to cross the harsh desert.
A Transatlantic ConnectionHaplogroup L2a is also common in the Americas. In fact, it is the most common haplogroup among African-Americans, reaching levels of 20%.The high frequency of L2a among African Americans is probably due to its concentration in West Africa, which was the main supply region for the Atlantic slave trade. The vast majority of African Americans bear a type of L2a that is found only in West Africa. L2a also made its way to South America through the slave trade; today a branch of L2a, L2a1, is found in up to 40% in some Afro-Brazilian populations.In the Spittoon...What can genetics reveal about African American ancestry? Find out at the Spittoon.
L2a in EuropeAlthough it is extremely rare in Europe, haplogroup L2a has been found among a small number of people there, mostly in the eastern part of the continent. It is most common among Ashkenazi Jews from Poland, but has also been found among Romanian, French, German and Russian Jews and non-Jewish Slavs in Slovakia and the Czech Republic.The distribution of L2a in Europe makes it very difficult to determine exactly how and when the haplogroup first appeared on the continent; but genetic analyses indicate that a migration from Africa during the Ice Age, more than 10,000 years ago.Source: https://www.23andme.com/you/haplogroup/maternal`