MITOEVE

Mitochondrial Eve (MitoEVE)

Mitochondrial Eve (MitoEVE)

Introduction

In the field of human genetics, Mitochondrial Eve (MitoEVE) refers to the matrilineal most recent common ancestor (MRCA) of modern humans. In other words, she was the woman from whom all living humans today descend, on their mother's side, and through the mothers of those mothers and so on, back until all lines converge on one person. Because all mitochondrial DNA (mtDNA) is generally passed from mother to offspring without recombination, all mitochondrial DNA (mtDNA) in every living person is directly descended from hers by definition. Mitochondrial Eve is the female counterpart of Y-chromosomal Adam, the patrilineal most recent common ancestor, although they lived thousands of years apart (Atkinson & Drummond, 2009).

Each ancestor (of people now living) in the line back to the matrilineal MRCA had female contemporaries such as sisters, female cousins, etc. and some of these female contemporaries may have descendants living now (with one or more males in their descendancy line). But none of the female contemporaries of the "Mitochondrial Eve" has descendants living now in an unbroken female line.

Discussion and Problems

Mitochondrial Eve is estimated to have lived around 200,000 years ago, most likely in East Africa, when Homo sapiens sapienses (natomically modern humans) were developing as a population distinct from other human sub-species. Mitochondrial Eve lived later than Homo heidelbergensis and the emergence of Homo neanderthalensis, but earlier than the out of Africa migration. The dating for 'Eve' was a blow to the multiregional hypothesis, and a boost to the hypothesis that modern humans originated relatively recently in Africa and spread from there, replacing more "archaic" human populations such as Neanderthals (Ayala, 1995). As a result, the latter hypothesis became dominant.

Many genetic conditions are related to changes in particular mitochondrial genes. This list of disorders associated with mitochondrial genes provides links to additional information. The following conditions are related to changes in the structure of mitochondrial DNA.

Cancers

Mitochondrial DNA is prone to somatic mutations, which are a type of noninherited mutation. Somatic mutations occur in the DNA of certain cells during a person's lifetime and typically are not passed to future generations (Ayala, 1995). There is limited evidence linking somatic mutations in mitochondrial DNA with certain cancers, including breast, colon, stomach, liver, and kidney tumors. These mutations might also be associated with cancer of blood-forming tissue (leukemia) and cancer of immune system cells (lymphoma).

It is possible that somatic mutations in mitochondrial DNA increase the production of potentially harmful molecules called reactive oxygen species. Mitochondrial DNA is particularly vulnerable to the effects of these molecules and has a limited ability to repair itself. As a result, reactive oxygen species easily damage mitochondrial DNA, causing a buildup of additional somatic mutations (Balloux & Handley, 2009). Researchers are investigating how these mutations could be related to uncontrolled cell division and the growth of cancerous tumors.

Cyclic Vomiting Syndrome

Cyclic vomiting syndrome may be related to genetic changes in mitochondrial DNA. Some of these changes alter single DNA building blocks (nucleotides), whereas others rearrange larger segments of ...