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Loren McIntyre. CHER Agency 
Increases in breathing and heart rates 
and red blood cell numbers are adjust- 
ments that most low-altitude residents 
make after arriving at high altitude. 
These short-term physiological re- 
sponses are fairly easy to identify. The 
issue biological anthropologists have 
found more intriguing is whether the 
physiological and morphological charac- 
teristics of highlanders that lowlanders 
are unable to duplicate are the result of 
gradual adjustments that accumulate 
during the developmental years or the 
result of unique genetic adaptations to 
high altitude. 
According to the best estimates, be- 
tween fifteen and twenty million people 
live above 10,000 feet in the Andes and 
on the Andean altiplano (“high pla- 
teau”), and another three to five million 
live above 10,000 feet in the Himalayas 
and on the Tibetan plateau. While a 
number of good cultural and biological 
studies have been carried out in both 
these areas, the greatest amount of data 
is available for two groups: the 8,000 or 
so Quechua Indians who live on the 
altiplano in the Nunoa district of south- 
ern Peru, and the approximately 2,500 
Sherpas who inhabit the Khumbu re- 
gion of eastern Nepal. The Sherpas do 
not actually live on the Tibetan plateau, 
but just south of it in the high alpine 
valleys of the Himalayas. Still, the Sher- 
pas are a Tibetan-derived group that 
possesses many features of the larger 
Tibetan culture, which has not been 
accessible for systematic biological or 
cultural investigation. Information on 
Nunoa comes from a large and well- 
integrated project initiated and, for the 
most part, directed by Paul T. Baker of 
Pennsylvania State University. Informa- 
tion on the Khumbu has not been col- 
lected as systematically, but taken as a 
whole forms a meaningful counterpart 
to the Nunoan data. 
As their names suggest, both the An- 
dean altiplano and the Tibetan plateau 
are relatively flat landscapes, consisting 
mainly of valleys separated by rolling 
hills. The floors of the valleys range 
from 10,000 to 15,000 feet; the hills are 
about 1,000 feet higher. The Andean 
altiplano is rimmed by the high Andes 
to the east, while the Tibetan plateau is 
rimmed by the Himalayas to the south. 
These mountain ranges act as moisture 
barriers, preventing most of the rainfall 
that makes South Asia and the Amazon 
so lush from penetrating the high-alti- 
tude plateaus. 
The Andean altiplano and the Ti- 
betan plateau are cold, but not frigid, 
areas. Nunoa falls within the tropical 
zone south of the Equator, where sea- 
sonal changes are not pronounced. Daily 
maximum temperatures remain consis- 
tently comfortable throughout the year: 
between 61° and 66 °F. Nighttime tem- 
peratures, on the other hand, do show 
some seasonal variation and can be quite 
cold: average lows range from about 37° 
during the rainy months of April 
through September to 14° during the 
dry months of October through March. 
Snow is uncommon, and when it does 
occur, it is light and quickly melted by 
the warm daytime temperatures. The 
Khumbu region of Nepal is located in 
the Northern Hemisphere’s temperate 
zone, at roughly the same latitude as 
Tampa, Florida. This position produces 
marked seasonality: in Khumbu villages 
between 11,000 and 12,000 feet, the 
average daytime maximum tempera- 
tures range from 39° during January to 
64° in July; average nighttime mini- 
mum temperatures range from 14° in 
January to 50° in July. Winter condi- 
tions are made even more severe by 
periodic snowfalls. With clothing, hous- 
ing, and other means, however, both the 
Quechuas and the Sherpas are able to 
modify their immediate environments to 
reduce cold stress significantly. 
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