Is there a genetic basis for adapting to life at high altitudes? a team of scientists from the united states and china set out to answer these questions. they began their search for a genetic basis for high-altitude hardiness by looking for genes that differed between the tibetan people and closely related, but low-dwelling, neighbors. they collected dna sequence data from 50 tibetans and 40 nearby chinese low-dwellers. for comparison, the scientists also collected dna sequence data from 200 low-dwelling danes, a more distantly related population.