Portal:Molecular anthropology

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Molecular anthropology

Molecular anthropology is a field of anthropology in which molecular analysis is used to determine evolutionary links between ancient and modern human populations, as well as between contemporary species. Generally, comparisons are made between sequences, either DNA or protein sequences; however, early studies used comparative serology.

By examining DNA sequences in different populations, scientists can determine the closeness of relationships between populations (or within populations). Certain similarities in genetic makeup let molecular anthropologists determine whether or not different groups of people belong to the same haplogroup, and thus if they share a common geographical origin. This is significant because it allows anthropologists to trace patterns of migration and settlement, which gives helpful insight as to how contemporary populations have formed and progressed over time.

Molecular anthropology has been extremely useful in establishing the evolutionary tree of humans and other primates, including closely related species like chimps and gorillas. While there are clearly many morphological similarities between humans and chimpanzees, for example, certain studies also have concluded that there is roughly a 98 percent commonality between the DNA of both species. However, more recent studies have modified the commonality of 98 percent to a commonality of 94 percent, showing that the genetic gap between humans and chimps is larger than originally thought. Such information is useful in searching for common ancestors and coming to a better understanding of how humans evolved.

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Distribution Haplogroup R1b Y-DNA.svg

The distribution of M343, a Y-chromosomal marker for the R1 subclade R1b. R1 is a subclade of Haplogroup R (Y-DNA), which is the most abundant Y-chromosomal haplogroup in Western Eurasia.


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Schematic illustration of maternal geneflow in and out of Beringia. Colours of the arrows correspond to approximate timing of the events and are decoded in the coloured time-bar. The initial peopling of Berinigia (depicted in light yellow) was followed by a standstill after which the ancestors of indigenous Americans spread swiftly all over the New World while some of the Beringian maternal lineages–C1a-spread westwards. More recent (shown in green) genetic exchange is manifested by back-migration of A2a into Siberia and the spread of D2a into north-eastern America that post-dated the initial peopling of the New World.
Schematic illustration of maternal (mtDNA) gene-flow in and out of Beringia, from 25,000 years ago to present.
Genetic history of indigenous peoples of the Americas primarily focus on Human Y-chromosome DNA haplogroups and Human mitochondrial DNA haplogroups. Autosomal "atDNA" markers are also used, but differ from mtDNA or Y-DNA in that they overlap significantly. The genetic pattern indicates Indigenous Amerindians experienced two very distinctive genetic episodes; first with the initial peopling of the Americas, and secondly with European colonization of the Americas. The former is the determinant factor for the number of gene lineages, zygosity mutations and founding haplotypes present in today's Indigenous Amerindian populations.

Human settlement of the New World occurred in stages from the Bering sea coast line, with an initial layover on Beringia for the small founding population. The micro-satellite diversity and distributions of the Y lineage specific to South America indicates that certain Amerindian populations have been isolated since the initial colonization of the region. The Na-Dené, Inuit and Indigenous Alaskan populations exhibit haplogroup Q (Y-DNA); however, they are distinct from other indigenous Amerindians with various mtDNA and atDNA mutations. This suggests that the peoples who first settled the northern extremes of North America and Greenland derived from later migrant populations than those who penetrated further south in the Americas. Linguists and biologists have reached a similar conclusion based on analysis of Amerindian language groups and ABO blood group system distributions.

Q-M3 is the predominant haplotype in the Americas at a rate of 83% in South American populations, 50% in the Na-Dené populations, and in North American Eskimo-Aleut populations at about 46%. With minimal back-migration of Q-M3 in Eurasia, the mutation likely evolved in east-Beringia, or more specifically the Seward Peninsula or western Alaskan interior. The Beringia land mass began submerging, cutting off land routes.

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Allan C. Wilson (18 October 1934 – 21 July 1991) was a pioneer in the use of molecular approaches to understand evolutionary change and reconstruct phylogenies. One of the great innovators of science, he revolutionised the study of human evolution. He is the only New Zealander to win the prestigious MacArthur Fellowship. He was the leading pioneer of the field of Molecular Anthropology.

A.C. Wilson first came to world attention when he published a paper titled Immunological Time-Scale For Human Evolution in Science magazine in December 1967. Together with doctoral student Vincent Sarich, Wilson argued that the origins of the human species could be seen through, what he termed, a "molecular clock". This was a way of dating, not from fossils, but from the genetic mutations that had accumulated since they parted from a common ancestor. The molecular clock estimated the length of time from divergence, given a certain rate of change. Wilson and his colleagues discovered that humans and chimpanzees were 99 percent identical in DNA sequence and that they shared a recent common ancestor far more recent than most paleoanthropologist at the time believed. Wilson also coordinated the discovery of the "Mitochondrial Eve" hypothesis, a female in Africa about 200,000 years ago from which all living females are related through their maternal ancestry.


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