Essay/Term paper: Human variations in high altitude populations

Essay, term paper, research paper:  Science

Human Variations in High Altitude Populations


Jessyca Caumo
26 november 1996

Thesis:The purpose of this paper is to describe the high altitude stresses and
the general adaptations made by the Tibetan population in the Himalayas and the
Quechua in the Andes.

I Introduction
II Background
A Quechua People
B Tibetan People
III General Adaptations
A Physical
1 Growth
2 Development
3 Core temperature
4 Extremity temperature
B Non- Physical
1 Clothing
2 Houses
3 Schedule
V Conclusion


"Some ten to twenty-five million people (that is less than 1% of the
earth"s population) currently make it[high altitude zones] their
home(Moran,143)." The adjustment high altitude populations must make are firstly
physical and secondly cultural. Although most people adapt culturally to their
surroundings, in a high altitude environment these cultural changes alone aren"t
enough. Many physical adaptations that reflect "the genetic plasticity common to
all of mankind(Molinar,219)" have to be made to survive and even more than that
thrive in this type of environment.
In this paper I will describe the high altitude stresses. Along with
adaptations made by the populations living in them. The two high altitude
populations which I will examine in this paper are the Tibetan people of the
Asian Himalayas and the Quechua of the South American Andes.
The Quechua are an Indian people who inhabit the highlands of Peru and
Bolivia. They speak Quechua, which is a branch of the Andean-Equitorial stock.
They show many remnants of Inca heritage by their houses, music, and religion
which has pagan rites under the Roman-Catholic surface. Their villages consist
of kin groups . Their marriage partners are taken from within each village.
Agriculture is the dominant subsistence pattern in the central Andean
region but the Nunoa region where the Quechua reside can only support a few
frost-resistant crops. Which include bitter potato, sweet potato, and a few
grain crops of quinoa and canihua. The rest of the fruits and vegetables of the
Quechua come from the eastern mountains on it"s way to the markets. The most
important subsistence pattern for the Quechua is stock raising. Which is limited
to the few animals that do well in the high altitudes. Their stock include
alpacas,llamas and sheep.
In the Himalayas only "5% of the geographical area(Baker,36)" can be
used for agriculture. The main crops are barley, wheat and buckwheat. The crops
are grown between 3,500 and 4,300 meters. These few crops are threatened by
drought, hail, frost, snow and erosion. The Himalayas also have extensive
pasture areas which are used by the nomadic and sedentary peoples. The higher
regions have pastures where yak, sheep, and goats are the main animals used.
In the high altitude there are many environmental stresses that the
people must endure. They include hypoxia, intense ultraviolet radiation, cold,
aridity, and a limited nutritional base. The people adapt to these stresses in
many ways.
Hypoxia, or low oxygen pressure, is the most prominent stress which
populations living at high altitudes must deal with. "Hypoxia results whenever
either physiological,pathological, or environmental conditions cannot deliver
adequate supply of oxygen to the tissues. Since air is compressible, air at high
altitudes is less concentrated and under less pressure. At 4500 meters the
partial pressure of oxygen is decreased by as much as 40%, in comparison to
pressure at sea level. This reduces the amount of oxygen finally available to
the tissue(Moran,147-148)." The adaptations to hypoxia are all geared towards
increasing the oxygen to the tissues.
One adaptation to hypoxia is an increase of red blood cells in
circulation. A person living in high altitude conditions is likely to have "30%
more red blood cells(Molinar,218)" than a person living at sea level. "This
greater number of red blood cells increases the hemoglobin concentration, which
in turn increases the oxygen -carrying capacity per unit volume of
blood(Molinar,219)." This then increases the oxygen sent to the tissues.
Respiration and cardiac output are also increased. There is an increase in the
capillary network to aid diffusion of oxygen to the tissues. There have also
been cellular changes that increase the resistance to the tissues to low oxygen.
Many other effects are felt from hypoxia. Growth and development are one
of the many areas affected. Kruger and Arias-Stella compared two populations at
4,570 meters and at 200 meters and found the mean placental weight of the high
population to be 561 grams as compared to the low-land population weight to be
500 grams. Placenta volumes did not differ showing that the placenta at the high
altitude was denser. The denser placenta offers the fetus more protection and
greater oxygen. The birth weights at high altitudes are uniformly lower than
that of low altitude. This is probably due to hypoxia but the nutritional
status of the mother"s must also be taken into account. A study by Frisancho
Velasquez and Sanchez demonstrated that subjects with short stature attained a
greater maximal aerobic capacity than their counterparts of a larger body size
when tested under identical conditions. It is known that " birth weight is said
to be correlated with maternal size particularly stature(Baker,95)" therefore
small birth weight is an effect of the adaptation of body size to deal with
hypoxia.
Growth and development in high altitude populations is considerably
slower than low-land growth.This may be due to the growth of their large chests
and the extra production of the red blood cells from the bone marrow. This extra
large chest growth increases the lung capacity to take in more oxygen. Although
in the Himalayas this increased chest size is not a factor.
Baker shows growth in stature occurs until the twenty second year. Sexual
dimorphism isn"t defined until the 16th year. Growth spurts also take longer to
occur. Fifteen to nineteen for boys and fourteen to seventeen for girls. The
mean weight for Sherpas and Quechua is 54 kilograms. Height is 140-160
centimeters. Menses between the Sherpas and Quechua differ. The mean age of
Sherpa women to begin menses is 18. For the Quechua it is thirteen although this
is compared to an Andean lowland mean of eleven.
Cold is another stress people of high altitudes must contend with. Three
things help these populations "one is a lack of dramatic fall in core
temperature 2) is a slightly elevated metabolic rate and 3) consistently high
extremity surface temperatures(Baker,277)." The elevated metabolic rate
generates a greater body heat. This greater blood flow helps maintain a warmer
skin surface. This is necessary because of the heat lost through the extremities.
Keeping the core temperature high is another adaptation which keeps the bodies
of these people warn even while at rest in their harsh environment.
There are many non-physical adaptations that people make to help them
adjust to the high altitude environment. Clothing is one of these adaptations.
Andean men wear "woolen homespun pants which are mid-calf in length. Worn over
one or more layers of loosely knit woolen underwear. A knitted,sleeveless
undershirt is used under a cotton shirt with long sleeves...A colorful jacket,
matching the pants, is also used. The outfit is completed with a felt hat and a
poncho.(Baker,263)." "Women wear several woolen skirts and a long sleeved jacket
of similar material. They also may use knitted underwear but like the men wear a
manufactured cotton blouse. Women carry over their shoulders a shawl which is
similar in construction to the poncho...Skirts are usually dark red or black as
are jackets(Baker,263)." Footwear is normally not worn. Shoes would be
detrimental during the rainy season because of the extra loss of heat. Also in
the hot weather the feet would sweat. In the Himalayas "Women are shown wearing
long-sleeved cotton blouses which are covered by woolen jackets and ankle length
length skirts. Men"s dress also seems substantial with long jackets,long pants
and heavy coats. As among Quechua Indians most Sherpas [name of one group living
in the Himalayas] seem to walk barefoot(Baker,261)." There have been no
detailed studies of the Sherpa clothing Houses are another adaptation people
have made. In the Andes there are two basic house designs. "The first uses adobe
or sod and is a permanent building. This type is usually found in towns and
represents a major investment. The second design is constructed of piled
fieldstone, is semipermanent, and is cheap to construct It is more
characteristic of areas where the population is largely pastoral. The adobe
building has a rectangular floor plan with average dimensions of 5 meters by 10
meters. The roof is gabled with a peak of 4 meters to 5 meters from the ground.
Frequently the first meter of the walls will be made of stone to resist erosion
due to rain draining from the roof. The roof is typically constructed of tile,
grass, or in more affluent families, corrugated tin. The door is small and it"s
height seldom exceeds 1.3 meters. Doors are usually wooden, but in some cases
blankets or old ponchos may be used to cover the openings. Walls are usually
plastered with mud to form an air right structure. The roof is tightly fitted,
regardless of the material used. In some cases a wooden floor may be added but
usually a natural dirt floor is preferred. Rooms may be employed for cooking ,
sleeping, or storage(Baker,260)."
For the semipermanent "The floor plan of these houses is circular or
rectangular with the upper walls sloping slightly inward. The roof is always
constructed of grass and supported by tree limbs. The diameter is quite variable
as is the height. The walls are made of fieldstone. If the house is to be
occupied for an extended period of time the stones are carefully piled to
eliminate cracks. Those large holes which remain and those at eye level are used
as windows; that is, they serve to admit daylight and provide for observation of
the surrounding terrain. These houses may have either a wooden door or a piece
of old cloth may be used to cover the entrance(Baker,259)." Baker measured the
interior temperatures of adobe houses during the cold and dry season and found
that well constructed adobe houses could maintain an interior nighttime
temperature 7 degrees Celsius above the ambient temperature. The thermal
protection offered by stone houses seems to be less than that of the adobe
structures. Baker reports that there is only 3.7 degrees Celsius difference
between indoor and outdoor temperatures.
The houses of the Himalayas are "constructed of heavy stone and have
wooden roofs which are held in place by stones. Most are two story structures
whose interior dimensions are rather small. They are apparently tightly
constructed because the first floor is reserved as animals quarters while the
second is reserved for human habitation. Cooking is done indoors with the smoke
escaping from a small hole in the roof. The use of the first floor as animal
quarters might add to the insulation between the floor of the human section and
the ground.(Baker,261)" There are no climatological data on these houses.
Scheduling of work is another way people cope. Normally rising after
dawn and "spending the day outside taking advantage of the solar
radiation(Moran,160) while working and playing. At sunset everyone goes to sleep.
Also at night most families sleep together in bed to share body heat.
The adaptations which have been made by these groups also have a down side
to them. There is as we"ve seen a slower growth, a higher infant mortality, and
even an increased frequency of respitory diseases. Along with this there is a
decrease of many micro-organisms which cause infectious diseases. As we consider
this give and take and whether we would ever subject ourselves to these things,
we must appreciate what these people go through. High altitude has many stresses
to which people must adapt. Although this life is hard the people would have it
no other way we should respect and commend them for that.

Bibliography

Allan, Nigel and Knapp,Gregory and Stadel,Christoph,eds.1988.Human Impact in
Mountains.Rowman&Littlefield:New Jersey. Baker,Paul and Little,Michael,eds.
1976.Man in the Andes. Dowden,Hutchinsonand Ross:Pennsylvania. Baker,Paul,ed.
1978.The Biology of High Altitude Peoples.Cambridge University Press:London.
Gibbons,Ida. 1996.Andean Cultures Web Page. Gibbons@andes.org. Molinar,Stephen.
1992. Human Variation. Prentice Hall:New Jersey Monge,Carlos.
1948.Acclimatization in the Andes.Maryland:The John Hopkins Press. Moran,Emilio.
1982.Human Adaptability.Westview Press:Colorado. Occasional Papers in
Anthropology. 1968.High Altitude Adaptation in a Peruvian Community.Pennsylvania
State University: Department of Anthropology. U.S. Department of
Health and Human Services. 1983.Adjustment to High Altitude.


References Baker,Paul,ed. 1978.The Biology of
High Altitude Peoples.Cambridge University Press:London. Gibbons,Ida.
1996.Andean Cultures Web Page. Gibbons@andes.org. Molinar,Stephen. 1992. Human
Variation. Prentice Hall:New Jersey Moran,Emilio. 1982.Human
Adaptability.Westview Press:Colorado.
Outline







"Some ten to twenty-five million people (that is less than 1% of the
earth"s population) currently make it[high altitude zones] their
home(Moran,143)." The adjustment high altitude populations must make are firstly
physical and secondly cultural. Although most people adapt culturally to their
surroundings, in a high altitude environment these cultural changes alone aren"t
enough. Many physical adaptations that reflect "the genetic plasticity common to
all of mankind(Molinar,219)" have to be made to survive and even more than that
thrive in this type of environment.
In this paper I will describe the high altitude stresses. Along with
adaptations made by the populations living in them. The two high altitude
populations which I will examine in this paper are the Tibetan people of the
Asian Himalayas and the Quechua of the South American Andes.
The Quechua are an Indian people who inhabit the highlands of Peru and
Bolivia. They speak Quechua, which is a branch of the Andean-Equitorial stock.
They show many remnants of Inca heritage by their houses, music, and religion
which has pagan rites under the Roman-Catholic surface. Their villages consist
of kin groups . Their marriage partners are taken from within each village.
Agriculture is the dominant subsistence pattern in the central
Andean region but the Nunoa region where the Quechua reside can only support a
few frost-resistant crops. Which include bitter potato, sweet potato, and a few
grain crops of quinoa and canihua. The rest of the fruits and vegetables of the
Quechua come from the eastern mountains on it"s way to the markets. The most
important subsistence pattern for the Quechua is stock raising. Which is limited
to the few animals that do well in the high altitudes. Their stock include
alpacas,llamas and sheep.
In the Himalayas only "5% of the geographical area(Baker,36)" can be
used for agriculture. The main crops are barley, wheat and buckwheat. The crops
are grown between 3,500 and 4,300 meters. These few crops are threatened by
drought, hail, frost, snow and erosion. The Himalayas also have extensive
pasture areas which are used by the nomadic and sedentary peoples. The higher
regions have pastures where yak, sheep, and goats are the main animals used.
In the high altitude there are many environmental stresses that the
people must endure. They include hypoxia, intense ultraviolet radiation, cold,
aridity, and a limited nutritional base. The people adapt to these stresses in
many ways.
Hypoxia, or low oxygen pressure, is the most prominent stress which
populations living at high altitudes must deal with. "Hypoxia results whenever
either physiological,pathological, or environmental conditions cannot deliver
adequate supply of oxygen to the tissues. Since air is compressible, air at high
altitudes is less concentrated and under less pressure. At 4500 meters the
partial pressure of oxygen is decreased by as much as 40%, in comparison to
pressure at sea level. This reduces the amount of oxygen finally available to
the tissue(Moran,147-148)." The adaptations to hypoxia are all geared towards
increasing the oxygen to the tissues.
One adaptation to hypoxia is an increase of red blood cells in
circulation. A person living in high altitude conditions is likely to have "30%
more red blood cells(Molinar,218)" than a person living at sea level. "This
greater number of red blood cells increases the hemoglobin concentration, which
in turn increases the oxygen -carrying capacity per unit volume of
blood(Molinar,219)." This then increases the oxygen sent to the tissues.
Respiration and cardiac output are also increased. There is an increase in the
capillary network to aid diffusion of oxygen to the tissues. There have also
been cellular changes that increase the resistance to the tissues to low oxygen.
Many other effects are felt from hypoxia. Growth and development are one
of the many areas affected. Kruger and Arias-Stella compared two populations at
4,570 meters and at 200 meters and found the mean placental weight of the high
population to be 561 grams as compared to the low-land population weight to be
500 grams. Placenta volumes did not differ showing that the placenta at the high
altitude was denser. The denser placenta offers the fetus more protection and
greater oxygen. The birth weights at high altitudes are uniformly lower than
that of low altitude. This is probably due to hypoxia but the nutritional
status of the mother"s must also be taken into account. A study by Frisancho
Velasquez and Sanchez demonstrated that subjects with short stature attained a
greater maximal aerobic capacity than their counterparts of a larger body size
when tested under identical conditions. It is known that " birth weight is said
to be correlated with maternal size particularly stature(Baker,95)" therefore
small birt h weight is an effect of the adaptation of body size to deal with
hypoxia.
Growth and development in high altitude populations is considerably
slower than low-land growth.This may be due to the growth of their large chests
and the extra production of the red blood cells from the bone marrow. This extra
large chest growth increases the lung capacity to take in more oxygen. Although
in the Himalayas this increased chest size is not a factor.
Baker shows growth in stature occurs until the twenty second year.
Sexual dimorphism isn"t defined until the 16th year. Growth spurts also take
longer to occur. Fifteen to nineteen for boys and fourteen to seventeen for
girls. The mean weight for Sherpas and Quechua is 54 kilograms. Height is 140-
160 centimeters. Menses between the Sherpas and Quechua differ. The mean age of
Sherpa women to begin menses is 18. For the Quechua it is thirteen although this
is compared to an Andean lowland mean of eleven.
Cold is another stress people of high altitudes must contend with. Three
things help these populations "one is a lack of dramatic fall in core
temperature 2) is a slightly elevated metabolic rate and 3) consistently high
extremity surface temperatures(Baker,277)." The elevated metabolic rate
generates a greater body heat. This greater blood flow helps maintain a warmer
skin surface. This is necessary because of the heat lost through the extremities.
Keeping the core temperature high is another adaptation which keeps the bodies
of these people warn even while at rest in their harsh environment.
There are many non-physical adaptations that people make to help them
adjust to the high altitude environment. Clothing is one of these adaptations.
Andean men wear "woolen homespun pants which are mid-calf in length. Worn over
one or more layers of loosely knit woolen underwear. A knitted,sleeveless
undershirt is used under a cotton shirt with long sleeves...A colorful jacket,
matching the pants, is also used. The outfit is completed with a felt hat and a
poncho.(Baker,263)." "Women wear several woolen skirts and a long sleeved jacket
of similar material. They also may use knitted underwear but like the men wear a
manufactured cotton blouse. Women carry over their shoulders a shawl which is
similar in construction to the poncho...Skirts are usually dark red or black as
are jackets(Baker,263)." Footwear is normally not worn. Shoes would be
detrimental during the rainy season because of the extra loss of heat. Also in
the hot weather the feet would sweat. In the Himalayas "Women are shown wearing
long-sleeved cotton blouses which are covered by woolen jackets and ankle length
length skirts. Men"s dress also seems substantial with long jackets,long pants
and heavy coats. As among Quechua Indians most Sherpas [name of one group living
in the Himalayas] seem to walk barefoot(Baker,261)." There have been no
detailed studies of the Sherpa clothing Houses are another adaptation people
have made. In the Andes there are two basic house designs. "The first uses adobe
or sod and is a permanent building. This type is usually found in towns and
represents a major investment. The second design is constructed of piled
fieldstone, is semipermanent, and is cheap to construct It is more
characteristic of areas where the population is largely pastoral. The adobe
building has a rectangular floor plan with average dimensions of 5 meters by 10
meters. The roof is gabled with a peak of 4 meters to 5 meters from the ground.
Frequently the first meter of the walls will be made of stone to resist erosion
due to rain draining from the roof. The roof is typically constructed of tile,
grass, or in more affluent families, corrugated tin. The door is small and it"s
height seldom exceeds 1.3 meters. Doors are usually wooden, but in some cases
blankets or old ponchos may be used to cover the openings. Walls are usually
plastered with mud to form an air right structure. The roof i s tightly fitted,
regardless of the material used. In some cases a wooden floor may be added but
usually a natural dirt floor is preferred. Rooms may be employed for cooking ,
sleeping, or storage(Baker,260)."
For the semipermanent "The floor plan of these houses is circular or
rectangular with the upper walls sloping slightly inward. The roof is always
constructed of grass and supported by tree limbs. The diameter is quite variable
as is the height. The walls are made of fieldstone. If the house is to be
occupied for an extended period of time the stones are carefully piled to
eliminate cracks. Those large holes which remain and those at eye level are used
as windows; that is, they serve to admit daylight and provide for observation of
the surrounding terrain. These houses may have either a wooden door or a piece
of old cloth may be used to cover the entrance(Baker,259)." Baker measured the
interior temperatures of adobe houses during the cold and dry season and found
that well constructed adobe houses could maintain an interior nighttime
temperature 7 degrees Celsius above the ambient temperature. The thermal
protection offered by stone houses seems to be less than that of the adobe
structures. Baker reports that there is only 3.7 degrees Celsius difference
between indoor and outdoor temperatures.
The houses of the Himalayas are "constructed of heavy stone and have
wooden roofs which are held in place by stones. Most are two story structures
whose interior dimensions are rather small. They are apparently tightly
constructed because the first floor is reserved as animals quarters while the
second is reserved for human habitation. Cooking is done indoors with the smoke
escaping from a small hole in the roof. The use of the first floor as animal
quarters might add to the insulation between the floor of the human section and
the ground.(Baker,261)" There are no climatological data on these houses.
Scheduling of work is another way people cope. Normally rising after
dawn and "spending the day outside taking advantage of the solar
radiation(Moran,160) while working and playing. At sunset everyone goes to sleep.
Also at night most families sleep together in bed to share body heat.
The adaptations which have been made by these groups also have a down
side to them. There is as we"ve seen a slower growth, a higher infant mortality,
and even an increased frequency of respitory diseases. Along with this there is
a decrease of many micro-organisms which cause infectious diseases. As we
consider this give and take and whether we would ever subject ourselves to these
things, we must appreciate what these people go through. High altitude has many
stresses to which people must adapt. Although this life is hard the people would
have it no other way we should respect and commend them for that.
Bibliography Allan, Nigel and Knapp,Gregory and
Stadel,Christoph,eds.1988.Human Impact in
Mountains.Rowman&Littlefield:New Jersey. Baker,Paul and Little,Michael,eds.
1976.Man in the Andes. Dowden,Hutchinsonand
Ross:Pennsylvania. Baker,Paul,ed. 1978.The Biology of High Altitude
Peoples.Cambridge University Press:London. Gibbons,Ida. 1996.Andean
Cultures Web Page. Gibbons@andes.org. Molinar,Stephen. 1992. Human Variation.
Prentice Hall:New Jersey Monge,Carlos. 1948.Acclimatization in the
Andes.Maryland:The John Hopkins Press. Moran,Emilio. 1982.Human
Adaptability.Westview Press:Colorado. Occasional Papers in Anthropology.
1968.High Altitude Adaptation in a Peruvian Community.Pennsylvania
State University: Department of Anthropology. U.S.
Department of Health and Human Services. 1983.Adjustment to High
Altitude.




References Baker,Paul,ed. 1978.The Biology of
High Altitude Peoples.Cambridge University Press:London. Gibbons,Ida.
1996.Andean Cultures Web Page. Gibbons@andes.org. Molinar,Stephen. 1992. Human
Variation. Prentice Hall:New Jersey Moran,Emilio. 1982.Human
Adaptability.Westview Press:Colorado.
Outline