In the Jan. 9, 2004, issue of Science, a UCI research team reports that key mutations in the mitochondrial DNA (mtDNA) of human cells may have helped our migrating ancestors adapt to more northerly climates, and ultimately link people with this ancestral history to specific diseases.
Found outside the cell's nucleus, mitochondria are the power plants of cells that are responsible for burning the calories in our diet.
The cellular energy is used for two purposes: to generate heat to maintain our body temperature and to synthesize ATP (adenosine triphosphate), a chemical form of energy that permits us to do work such as exercise, think, write, and make and repair cells and tissues. The mtDNAs are the blue prints for our mitochondrial power plants and determine the proportion of the calories in our diet that are allocated to generate body heat versus work.
According to Douglas C. Wallace, the Donald Bren Professor of Biological Sciences and Molecular Medicine at UCI and one of the co-authors of the report, after early humans migrated to colder climates, their chances of survival increased when mutations in their mtDNA resulted in greater body heat production during the extreme cold of the northern winters.
"In the warm tropical and subtropical environments of Africa it was most optimal for more of the dietary calories to be allocated to ATP to do work and less to heat, thus permitting individuals to run longer, faster and to function better in hot climates," Wallace said. "In Eurasia and Siberia, however, such an allocation would have resulted in more people being killed by the cold of winter. The mtDNA mutations made it possible for individuals to
Contact: Iqbal Pittalwala
University of California - Irvine