Changes in DNA tied to climate

WASHINGTON -- People native to the far north evolved to produce more heat in their cells, a new study says. The researchers suggest this change is a climate-driven effect.

The change occurs in the mitochondria, the parts of human cells that burn fuel to produce heat and energy, according to the team of researchers led by Eduardo Ruiz-Pesini of the University of California at Irvine.

The scientists analyzed mitochondria from 1,125 people ranging from Africa to Europe and Arctic Siberia.

They found that populations closer to the pole were more likely to have mutations in their mitochondrial DNA that increase production of heat and reduce production of energy.

The change results in an increased propensity for energy deficiency diseases, but also in increased longevity and resistance to aging, they report in yesterday's issue of the journal Science.

"Our observations support the hypothesis that certain [mitochondrial DNA] variants permitted humans to adapt to colder climates," the researchers concluded.

The variants continue to

produce differences in energy production and affect health, they said. DNA molecules provide the blueprint for the development of the body, combining information from each parent. Mitochondrial DNA, which directs the energy production in cells, is inherited only from the mother.