Hypothesized world map of human migrations, with the North Pole at center. Africa, harboring the start of the migration, is at the top left and South America at the far right. Migration patterns are based on studies of mitochondrial (matrilinear) DNA. Letters represent haplogroups while colors and numbers represent thousands of years before present.
Suggested migratory route of the "Out of Africa" migration according to Mitochondrial DNA
In human genetics, a human mitochondrial DNA haplogroup is a haplogroup defined by differences in human mitochondrial DNA. Haplogroups are used to represent the major branch points on the mitochondrial phylogenetic tree. Understanding the evolutionary path of the female lineage has helped population geneticists trace the matrilineal inheritance of modern humans back to human origins in Africa and the subsequent spread across the globe.
The letter names of the haplogroups run from A to Z. As haplogroups were named in the order of their discovery, they do not reflect the actual genetic relationships.
Bryan Sykes had claimed there were seven major mitochondrial lineages for modern Europeans but others now put the number at 10-12. These additional "daughters" generally include haplogroups I, M and W. A recent paper re-mapped European haplogroups as H, J, K, N1, T, U4, U5, V, X and W. It should however be noted that haplogroups are arbitrary categories defined by mutations, which themselves are numerous and the result of a random process. It could reasonably be said that there are almost any number of haplogroups present in a particular region. Furthermore, attributing a specific geographic origin to any haplogroup, such as those proposed in the table below, is highly speculative and considered by most population geneticists[who?] to be 'story telling' and outside the domain of science. The same can also be said of inferring a close association between a specific haplogroup and a particular archaeological culture.[who?]
Sharma S, Saha A, Rai E, Bhat A, Bamezai R (2005). "Human mtDNA hypervariable regions, HVR I and II, hint at deep common maternal founder and subsequent maternal gene flow in Indian population groups". Journal of Human Genetics50 (10): 497–506. doi:10.1007/s10038-005-0284-2. PMID16205836.