"These were two different evolutionary experiments," Beall said of the mountain dwellers in Tibet and Ethiopia. "On one levelthe biological responsethey are the same. On another levelthe changes in the gene poolthey are different."
Beall investigated the adaptations and genetic links with Gorka Alkorta-Aranburu, David Witonsky, Jonathan K. Pritchard and Anna Di Rienzo, of the University of Chicago department of human genetics, and Amha Gebremedhin of Adis Ababa University's department of internal medicine in Ethiopia.
In addition to studying the Amhara, the researchers looked for changes in physiology and genetics among a related ethnic group, the Oromo, who have lived more than a mile above sea level in the Bale Mountains of southern Ethiopia for 500 years.
They found no long-term adaptation and no genetic changes related to a low-oxygen environment.
They found the Omoro had high levels of hemoglobin, as would be expected for a lowland population.
Using the same samples collected from the Amhara and Oromo, the researchers are now studying biological traits among the groups, including ventilation, and the influence of vasoconstrictors and vasodilators on blood flow, and searching for associations with genes.
They also plan to continue research and study blood flow, especially through the heart and lungs of the highlanders, and to test the metabolic rate of mitochondria that use oxygen to create the energy on which our cells and we operate.
"We also want to find whether people with the variants for low hemoglobin levels have more children and a higher survival rate," Beall said. "That's the evolutionary payoff."
|Contact: Kevin Mayhood|
Case Western Reserve University