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Applied Geography 40 (2013) 212e221
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Applied Geography
journal homepage: www.elsevier.com/locate/apgeog
Altitude and adaptation: A study of geography and ethnic division
Christopher Paik a, *, Tsering Wangyal Shawa b
a
b
New York University Abu Dhabi, United Arab Emirates
Map and Geospatial Information Center, Princeton University
a b s t r a c t
Keywords:
Cohabitation
China
Tibet
Diversity
Ethnography
Ethnic division
Altitude
Altitude illness
In this paper we investigate the influence of geography on ethnic division by drawing evidence from
Tibetan ethnic regions in China. Using a novel township name index that identifies the ethnolinguistic
origin of each township name, our empirical findings first show that regions with Han Chinese settlement in the past also witness higher concentration of Han population today. We also show that townships located at higher altitudes have less Han concentration. This altitude effect can be both indirect and
direct; we find that the indirect effect through historical settlement is small compared to the direct
physiological effect through altitude illness. The challenging environment of the plateau region acts as a
physiological hindrance only for Han Chinese, and the natural separation continues to persist between
the two groups.
Ó 2013 Elsevier Ltd. All rights reserved.
Introduction
Geography has long been instrumental in understanding
various socioeconomic processes, including ethnic conflict and civil
wars (Fearon & Laitin, 2003; Jha, 2009; Miguel, Satyanath &
Sergenti. 2004; Wimmer, Cederman, & Min, 2009), as well as
divergence in institutional performance and economic development (Acemoglu, Johnson, & Robinson, 2001; Acemoglu Johnson &
Robinson 2002; Acemoglu, Johnson, & Robinson, 2005; Easterly,
2001; Easterly & Levine, 2002). While cultural and technological
innovations have perhaps facilitated human adaptation to changes
in nature over the years (Amaru & Chhetri, 2013; Eriksen & Selboe,
2012; Folke, Hahm, Olsson & Norberg 2005; Moser & Ekstrom,
2010; Nielson & Reenberg, 2010), socioeconomic divergence due
to environmental barriers often persists in the long run, such that
both historical processes and geography continue to influence the
present. This persistence suggests that natural surroundings
sometimes impose constraints especially on migrants who, despite
efforts to put down their roots, may not overcome the changes they
face in the new environment. The constraints that they face may
even be physiological and different from cognitive-behavioral responses to adapting to new climate or places (Fresque-Baxter &
Armitage, 2012). In this paper we specifically aim to identify the
various causal mechanisms of geography on the familiar yet
* Corresponding author.
E-mail addresses: [email protected] (C. Paik), [email protected]
(T.W. Shawa).
0143-6228/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.apgeog.2013.02.003
important outcome of ethnic division. In support of different works
that have identified geographic variability as the foundation of
ethnic diversity (Ahlerup & Olsson, 2012; Michalopoulos, 2012), we
analyze the extent to which the effect of geography has persisted in
the long run. Specifically, we first investigate both the origin of
Han-Tibetan diversity and ethnic diversity today in Tibetan regions.
We exploit the fact that the two groups continue to be separated by
the regions’ high altitude. We then separate the impact of elevation
on ethnic division, by exploring both its influence today and
throughout history. In doing so we test whether the altitude effect
is only indirect and temporary through historical settlements, or
direct and persistent on the present population.
We study Tibet as a unique case of how altitude can have a
significant effect on ethnic diversity, as altitude illness predominantly affects Han Chinese but not Tibetans. China’s rising prominence in the world today, combined with the recent wave of protest
movement and ongoing conflict between Han Chinese and Tibetans, has also sparked a renewed interest among both academics
and policy makers. Altitude illness is a well-known medical condition that occurs when a person ascends to high mountainous
slopes and suffers from lack of oxygen (known as hypoxia).
Numerous studies have shown that Tibetans and Chinese have
different genetic compositions, and that certain genes carried by
Tibetans allow them to adapt better to the thin air surroundings
than Chinese (Beall et al., 1998; Bigham et al., 2010; Groves et al.,
1993; Gupta, Rao, Anad, Banerjee, & Boparai, 1992; MacInnis,
Koehle, & Rupert, 2010; Moore, 1998; Simonson et al., 2010; Wu,
Li, & Ward,, 2005). The Qinghai-Tibetan plateau, where Tibetans
live, is bounded by the Himalayas in the south and the west, and the
C. Paik, T.W. Shawa / Applied Geography 40 (2013) 212e221
Kunlun and Qilian mountains in the north and the east. On the
northern side of the Himalayan watershed, Tibet, now divided
among the Tibetan Autonomous Region of the Peoples’ Republic of
China and several other Chinese provinces, has an average elevation of 4380 meters. Covering more than 2.5 million kilometerssquared, the Qinghai-Tibetan plateau is the highest and largest
plateau in the world. Wu (2001) reports that in 1990 about
4,594,188 Tibetans lived on the plateau, with 53 percent living at an
altitude over 3500 meters. Furthermore, about 600,000 live at an
altitude exceeding 4500 meters in the Chantong-Qingnan area.
Tibetans are lifelong high-altitude residents and do not easily move
to higher or lower elevation.1 The fact that a majority of Tibetans
live at the altitude comparable to the Andeans in South America
suggests that Tibetan’s ability to adapt to their landscape is unique
to the people.
Taking advantage of the native background of one of the authors
in this paper, we introduce a novel data set containing the names of
all townships in Tibetan regions. With this data, we use the ethnic
origin of the town name to infer any historical Chinese presence in
the area. While a small number of these township names are recent
outcomes of the central government’s effort to establish Handominated towns in Tibet, most go back in history at least to the
13th Century. This was the period when the first formal contact took
place between the Yuan Dynasty and Tibet, a kingdom then only
known by pilgrims and surrounded by almost insurmountable natural barriers restricting access for foreigners. We argue that, given
the lack of historical data on the ethnic composition of each township population, the township name is a good proxy for historical
Chinese presence in the region.2 For comparison between the past
and the present population, we match these names with the National
Bureau of Statistics of China’s Historical China Township Population
Census Data with GIS Maps for the year 2000 (the year for which the
most recent census data at the township level are available).
Our main findings suggest that both historical settlement and
altitude effect are significant determinants of current ethnic division. First, townships with at least some evidence of Chinese
presence in the past see a 0.12 point increase in the fraction of
population identified as Han Chinese in 2000. Second, on average a
higher elevation by 1000 meters means a 0.18 point decrease in the
Han fraction of township population. This altitude effect can be
further separated into indirect and direct effects. Once migrants
settle down, they put down their roots so that both the descendants
and kin group become easily adapted to the land in subsequent
generations. The altitude effect would have influenced both the
population groups in the past, and also in the present. The indirect
altitude effect through historical presence, while significant, has
only limited impact (0.03) on the current population today. Its
magnitude is only one fourth of the direct effect (0.12) on the level
of Han concentration. These findings show that altitude not only
influenced the historical legacies of ethnic diversity, but continues
to have much stronger and direct impact on the current population.
They also suggest that any policies aimed at changing the ethnic
demography in Tibetan regions will likely face difficulties in surmounting the lasting effect of elevation.
This paper follows closely the social sciences literature on
ethnic demography and genetic divergence of groups (Fearon,
1
Wu (2001) reports that over 90 percent of the population are engaged in
farming and herding; in farming the altitude limit of crops is around 4500 meters,
while the nomads reside between 4800 and 5500 meters. Even the recent shift of
some livelihood into mining has not changed the permanent residence of Tibetans
at altitudes between 3700 and 6000 meters.
2
Here the term Chinese predominantly refers to the Han people but is inclusive
of Manchus who founded the Qing Dynasty, since Manchus and their language have
been assimilated into the Han population.
213
2003; Montalvo & Reynal-Querol, 2005; Spolaore & Wacziarg,
2009). It also complements seminal works by Goldstein (1997)
and Barnett (2009) on Tibet, by employing quantitative methods
to study a region that has hitherto lacked such analysis. In regard
to the cultural, institutional and technological innovations that
facilitate adaptation (Chhetri, Chaudhary, Tiwari, & Yadaw, 2012,
Chhetri & Easterling, 2010; Moser & Ekstrom, 2010), this research
provides a rare case study for which these adaptation advances
may prove yet ineffective in the face of certain natural barriers.
Finally, the research adds to the highly interdisciplinary field of
mountain geography by bringing together studies from the medical, anthropology, linguistics, political science and economics
literature. The rest of the paper proceeds as follows: in Section 2
we first discuss altitude illness, the main exogenous variation we
exploit to explain the natural separation between Tibetans and
Han Chinese. We then present arguments for how the township
name may be an appropriate indicator of the region’s ethnic history in Section 3. In Section 4 we discuss the empirical strategy
and describe the data in Section 5. Finally we provide the empirical findings in Section 6, and conclude in Section 7.
Natural separation and altitude illness
Ancient records indicate that the human difficulty with rarefied
air at high altitudes has existed for a long time. Writings attributed
to Aristotle (384e322 BC) for example describe travel on Mount
Olympus in Macedonia: “Also, because the rarity of the air which
was there did not fill them with breath, they were not able to
survive there unless they applied moist sponges to their noses”
(West, 1998). Ward (1990) documents the first recorded case of
altitude illness coming from the Karakorums, with Chinese sources
dating to 37e32 BCE describing the route from Yarkand to
Afghanistan as passing the aptly named ‘Great Headache’ and ‘Little
Headache’ mountains. McKay (2007) also presents an account of
the well known Chinese Buddhist traveler Fa-Hsien, who took the
western route to India in 399e414 CE. He describes a death from
what was probably high-altitude pulmonary edema, or swelling of
lungs. In contrast, Tibetan sources are mainly reticent about their
landscape and the difficult journeys undertaken through it;
furthermore, accounts of Tibetans suffering altitude sickness are
extremely uncommon (McKay 2007). The psychological impact of
la-drak, or “The Poison of the Pass,” or the “exhalations of
mischievous Gods” (West, 1998) would have been even greater on
Chinese in the ancient times, when the scientific cause of altitude
illness was not known.3
Altitude illness is a collective term that encompasses major
conditions caused directly by hypobaric hypoxia, or lack of oxygen
due to falling in partial pressure oxygen in high altitudes (Murdoch,
Pollard & Gibbas 2006, chap. 15). It is the only condition in which
traditional technology is incapable of mediating its effects among
the various environmental stresses that modern humans have
encountered and succeeded in overcoming (Peng et al., 2011).
Deprivation of adequate oxygen supply leads to severe physiological stress, leading to a number of symptoms including headache,
loss of appetite, nausea, vomiting, fatigue, weakness, dizziness,
light-headedness or sleep disturbance. Left untreated, severe forms
of altitude illness may result; Acute Mountain Sickness (AMS)
might progress to fatal high altitude cerebral edema (HACE), or
3
Paik (2013) provides a detailed summary and literature review on this topic,
showing that an increase in elevation is directly correlated with less presence of
Han population in the region. The paper also shows that the impact of elevation on
Han population is through altitude illness, and not through other contemporaneous
factors, such as urbanization and education attainment levels.
214
C. Paik, T.W. Shawa / Applied Geography 40 (2013) 212e221
swelling of extremities and face, that leads to brainstem herniation,
or high altitude pulmonary edema (HAPE), or swelling of lungs that
lead to difficulty in breathing.
A comparison between Tibetans and Han Chinese shows that
there is a much lower frequency of acute mountain sickness among
the highlanders owing to genetic adaptation (Wu et al., 2005).
Chronic mountain sickness, a disease that tends to occur later in life
among natives or long-life high-altitude residents, is also less
common in Tibetans than in similarly exposed Andeans (Moore,
1998). A number of highly selected genes play a role in maintaining hematocrit levels (the ratio of red blood cells to the total volume
of blood), which may contribute to this apparent resistance
(Bigham et al., 2010). The overall number of people impacted by
either AMS or CMS is relatively few (León-Velarde et al. (2005)
reports that about 5e10 percent of population in highlands are
affected), but the number naturally increases past different stages
of high altitudes, and affects Chinese much more than Tibetans.
Town names and heritage
We use the names given to each town as artifacts reflecting
historical Chinese influence in Tibet. The assertion that place
names, or toponyms, are outcomes of the past cultural and political
landscape finds much support from the linguistics and geography
literature. For example, Radding and Western (2010) shows that
names are given intentionally to impart a certain meaning, and that
they have layers of meanings that people do not want to see erased;
toponyms are deeply entrenched in culture, and their substitutions
come with consequences. The authors in Radding and Western
(2010) go on to argue that even literal or phonetic translation is
one type of name change that can be construed as a political act,
since the meaning of names is embedded in cultures, and translating a name runs the risk of destroying its meaning. Place names
are therefore “one of the most conservative elements in a
language. surviving even repeated language shift” (Burenhult &
Levinson, 2008). Their resilience is reflected often in cases when
both internal societal changes and external threats from another
language or society supplant the existing one, and yet the place
name may well remain (Herman, 1999).
When a political regime takes over another, multiple place
names may be created, each used by different groups. Even more
dramatic shifts in political regimes are reflected in the complete loss
of original toponyms. The name changes can therefore be interpreted as outcomes of political shifts, often imposed by colonial
authorities who use name changes as means to aid in the establishment and legitimation of a state (Radding & Western, 2010).
Horsman (2006) similarly argues that bestowing a name on a
physical entity is an act of appropriation, and with each change in
political regime comes new names for a given geographical location.
Kangding, the prefectural capital of Ganzi in Tibet Autonomous
Prefecture (TAP), Sichuan Province, is a good example of how a
township name represents the region’s history. The city has historically been known among Tibetans as Dartsedo. In an old Qing
map published by Christian missionaries in 1717 (d’Anville, 1737),
Dartsedo is labeled as Tachienlu, apparently the phonetic translation of Dartsedo. Since the Qing Dynasty, the Chinese kept a
garrisoned office in this important trading mart for both Tibetan
and Chinese merchants. The name Kanding reflects the historic
Chinese presence in the region; in 1725 the Qing military occupied
Dartsedo area and a place called Kata near Dartsedo, which was
made the military headquarters for the Chinese Troops. The capital
was subsequently renamed Kangding by the Chinese. Xihai City is
another example; the city is the prefectural capital of Haibei TAP,
Qinghai Province with no Tibetan heritage. Xihai, also known as
Two Two One Factor (Er Er Yao Chang), is a former site of China’s
top-secret nuclear weapons research. Xihai means the western sea,
the name of the first and only Chinese administrative unit established in the immediate locale before the 20th century. The name
therefore reflects a carefully-chosen historical parallel for the Chinese, and takes after the original “Xihai Commandery,” a military
settlement whose ruins lie little more than ten kilometers away.
(Marshall & Cooke, 1997; Pg. 1724).
Empirical strategy
Our empirical approach is to use town names as indicators of
historical Chinese presence in the region. We first assume that when
Han Chinese moved to the west toward Tibet, they made their marks
in the land close to the border and attractive for trade and military
purposes. That is, whether or not to settle in a region was a function
of how much one could gain from trade or territorial takeover, as
well as how close it was to the Chinese-dominant regions. This
assumption will be violated if regions differed in important ways in
their initial conditions that may also have had an effect on these
areas, for example, through variations in the type of biogeography
suitable for Chinese. The more attractive for agriculture a region
was, for example, the more likely it would have been settled by the
migrants. One may also argue that the due to lifestyle differences,
Tibetan agriculturalists may have had different cultural ties to Han
Chinese than Tibetan herders, which in turn affected the level of
Chinese settlement.4 In order to control for these alternative
mechanisms, we introduce a set of location as well as biogeographic
control variables, in addition to the altitude variable.
Elevation is directly correlated with the likelihood that the
Chinese would have become ill due to high altitudes. It identifies
variations in “Tibetanness” due to altitude mountain illness. The
historical Chinese presence in certain Tibetan towns may have been
influenced by the group’s inability to adapt to new altitudes, and
this physiological hindrance to living in certain places led to
different levels of Chinese presence across Tibet and its surrounding regions. We assess the impact of altitude on population,
whether through the past settlement or through its physiological
impact today. In order to do this we first run reduced-form equations of the following simple form:
Hi ¼ a0 þ a1 Ai þ a2 Xi þ εi1
(1)
where Hi is the fraction of population identified as Han Chinese in
township i in our sample, Ai is the altitude variable, Xi is a vector of
control variables, and ε is a normally distributed error term. The
parameter of interest in this setting is a1, showing the reducedform impact of altitude on current Han concentration. Our hypothesis is that a1 is negative, i.e. an adverse average impact of
elevation on Han population. Since we recognize a key role of
historical presence as an intermediate variable, we will also employ
the standard estimation of mediation effects (MacKinnon, 2008).
Mediation analysis is based on the following set of linear equations:
Mi ¼ b0 þ b1 Ai þ b2 Xi þ εi2
(2)
Hi ¼ q0 þ q1 Ai þ q2 Mi þ q3 Xi þ εi3
(3)
4
Michalopoulos (2012) for example argues that the origin of different ethnic
groups may come from variations in biogeography of the land, which determines
different lifestyles and occupations of the people. It is not clear however whether
Tibetan agriculturalists associated themselves as closer to Han migrants, who were
predominantly agricultural, or to their Tibetan neighbors herding animals at higher
altitudes.
C. Paik, T.W. Shawa / Applied Geography 40 (2013) 212e221
where Ai represents the mean altitude for township i, Mi represents
the mediating variable, in this case the indicator variable for
whether there was any historical Han Chinese presence, and Hi is
the current Han population as the fraction of total township population. Xi represents a set of observed exogenous geographic
covariates. The product of coefficients b1q2 estimates the average
causal mechanism effect (ACME), where b1 and q2 are obtained by
separately fitting least squares regressions based on the above
equations. a1 and q1 measure the average and the direct effect of
altitude on Han concentration, respectively. A significant q1 will
indicate that the altitude itself had an impact on current Han
presence independent of historical settlement. As with a1, we hypothesize that q1 is negative. Finally, a significant and positive q2
will suggest that a history of Han settlement explains a higher
current level of Han Chinese population, controlling for elevation
and other geographic variables.
Data
We use the township-level Han population data from China’s
National Bureau of Statistic’s Historical China Township Population
Census Data with GIS Maps for the year 2000. In order to assess the
extent to which a homogenous Tibetan region historically witnessed Han Chinese influence, we introduce a novel index of town
name classifications, and argue that these names are indicators of
the past history. We use Tsering W. Shawa’s Tibet Township Map and
Place Name Index Database based on the 2000 Chinese census
township level administrative units. This index includes Tibetan,
Chinese and English script township names in Tibet Autonomous
Region (TAR), as well as Tibet Autonomous Prefectures (TAP) and
Counties (TAC) in the surrounding provinces of Gansu, Qinghai,
Sichuan and Yunnan.
The year 2000 was the first time the Chinese township level
census data became available to the public. The township is a
fourth-level of census geography unit. It includes Jiedao (the urban
street location which is part of a larger urban area), Zhen (township with an urban population), and Xiang (township with no
urban population). In addition, the township classification includes virtual townships such as sheep breeding areas, special
farming areas, etc. The township names are written in three
scripts: Tibetan, Chinese, and English. Pinyin is the romanization
standard for Chinese script, and Wylie is a standard transliteration
of Tibetan script in scholarly literature in the English world. The
romanization is provided for a general reader to sound out Tibetan
town names. The Wylie transliteration is created from Tibetan
script using Universal Tibetan Font Converter. The program was
developed by Tashi Tsering at the China Tibetology Research
Center in Beijing.
The main motivation for creating the index was to record traces
of remaining Tibetan place names in traditionally Tibetan towns.
Some of these towns have increasingly seen changes in the
composition of population groups. Recording each town’s existing
name in various scripts required finding information from various
sources, including the official toponym lists published by the Chinese government in these areas, the Tibet map in Tibetan language
published by Tibetan-Government-Exile and by Amnye Machen
Institute, and toponym database from the Tibetan and Himalayan
Library. In the few case that there were only Chinese toponyms on
official records but the authors recognized the existence of Tibetan
counterparts for the towns through Shawa’s own heritage and
personal interviews with townspeople, these Tibetan names were
recorded as well.
For the purpose of the following empirical analysis, this paper
introduces another classification of these toponyms. Each town is
first categorized as having only a Chinese name (C), both Chinese
215
and Tibetan names (CT), or only a Tibetan name (T). Since all towns
have their official names written in Chinese characters and in
Pinyin, the extent to which the original town name has been preserved is determined by how phonetically or literally it is similar to
the Tibetan counterpart (if the Tibetan name does exist). A town in
the C-category means that it has a name instantly recognizable as
Chinese with no counterpart in the Tibetan language; that is, the
town name has no literal or phonetic connection to any Tibetan
word. This implies no Tibetan population and only Chinese
presence in history, or recent foundation of the town under the
government initiative to relocate Han Chinese to the town. In either
case, historical Tibetan presence is essentially non-existent in the
area.
A town in CT category on the other hand has two distinct names,
one in Chinese and one in Tibetan. Furthermore, the Chinese name
is not a phonetic or literal translation of the Tibetan name, such that
each name has its own origin. The categories C and CT are therefore
labeled as those that witnessed at least some Chinese settlement in
the past. A town in the T category has a Chinese name that is the
direct phonetic translation of the town’s Tibetan name. In a small
number of cases, Chinese town names are literal translations of the
Tibetan counterparts and are also coded as T. As an example, the
town of Yeniugou (Donglung in Tibetan) in Qinghai Province is
classified as having only a Tibetan town name, despite the pronounced difference in the two town names. Both Yeniugou and
Donglung in fact mean the same thing; they are translated as the
wild yak country. There are 1960 townships in the 141 counties of
the five provinces included in the dataset. 50 towns were dropped
due to ambiguity of name origins.
Appendix A presents a set of examples from Tibet Township Map
and Place Name Index Database. The 22 towns in Kangding County,
Sichuan Province, show both Chinese and Tibetan origins.
Geographically the region has had close contact with Chinese as it
lies close to the eastern edge of the traditional Tibetan region of
Kham, a main gateway region of Tibet to China. We see that in a few
cases the town’s ethnic name origin is not representative of the
current level of Tibetan population. For example, Liuba (Lugpa in
Tibetan) is a town with the total population of 2660 in the year
2000. 98 percent of the population is Tibetan, and the Chinese
name is a phonetic translation of the Tibetan name. The town name
is hence classified as having only a Tibetan originated name (T).
Pusharong (Phouharrong in Tibetan), on the other hand, is a town
with a Chinese name that has no recognizable Tibetan counterpart,
despite its dominant Tibetan population (97 percent). Another
example is the town of Jiju (Kyikyi) with 99 percent Tibetan population. It has both Tibetan and Chinese names distinct from each
other, despite the dominant presence of Tibetan population in
2000. The Chinese town names therefore do not always indicate
current Chinese population dominance in the town, but rather
suggest Chinese presence in history.
The following analysis controls for a number of geographic
variables. Each county’s ecological surroundings are defined by a
set of fractions of the land occupied by different biomes from ESRI
2008 Data. These biomes are identified as climatically and
geographically different from each other. Temperate Broadleaf and
Mixed Forests, and Temperate Conifer Forests are grouped together
as Temperate Forest (Mixed Forests include Coniferous forests).
Other types of biomes include Shrublands (Deserts and Xeric
Shrublands, and Montane Grasslands and Shrublands), Rock and
Ice, and Tropical and Subtropical Moist Broadleaf Forests. The set of
ecological variables, together with the mean elevation, provide
information on the type of plant structures, climate and vegetation
occupying each county. They proxy for the different habitat types
which likely influenced the initial settlement patterns of people in
history. Here we use the contemporary biogeographic data to
216
C. Paik, T.W. Shawa / Applied Geography 40 (2013) 212e221
Table 1
Summary statistics.
Variables
Fraction of population identified as Han in 2000
¼1 if historically settled by Han
Mean elevation in km
Area in 100 km-squared
Longitude
Latitude
Fraction covered by rock and ice
Fraction covered by shrublands
Fraction covered by tropical forest
Fraction covered by temperate forest
¼1 If township in Gansu
¼1 If township in Qinghai
¼1 If township in Sichuan
¼1 If township in Xizang
¼1 If township in Yunnan
(1)
(2)
(3)
(4)
(5)
N
Mean
sd
min
max
1709
1910
1960
1960
1960
1960
1960
1960
1960
1960
1960
1960
1960
1960
1960
0.191
0.229
3.813
0.110
97.49
32.17
0.007
0.738
0
0.254
0.068
0.255
0.294
0.369
0.015
0.296
0.421
0.812
0.378
5.610
2.802
0.045
0.383
0.014
0.383
0.252
0.436
0.456
0.483
0.121
0
0
1.265
0.490
78.96
27.08
0
0
0
0
0
0
0
0
0
1
1
5.762
7.939
104.6
38.91
0.560
1
0.577
1
1
1
1
1
1
proxy for historical vegetation spread prior to human settlement.
This approach presents potential pitfalls, since vegetation types
may have changed regionally over a long time. The measurement
error may also be systematic, in that both the settlement decision
and vegetation may be affected by the same factor, thereby producing a spurious result. In order to address these issues we
conduct our analysis by including provincial fixed effects, accounting for any provincial-level unobserved factors that may have
affected both the Han Chinese presence and vegetation spread.
This approach controls for any bias induced by within-province
unobserved heterogeneity. Finally, the following empirical analysis also includes geographic coordinates and the area of each
township.5
Findings
Map 1 shows the boundaries surrounding Tibetan Autonomous
Prefectures (TAP), inclusive of Tibetan Autonomous Region (TAR)
and Tibetan-dominated parts of other provinces. Table 1 presents
summary statistics, first showing the fraction of township population identified as Han Chinese in the year 2000. The average
township had about 19 percent of the population identified as Han.
For comparison, on average 23 percent of all townships experienced at least some historical Chinese influence, according to the
town names. The average township elevation is 3813 meters, and
out of 1960 townships 1500 of them are located at altitudes lower
than 4500 meters, which approximates the mean elevation of the
plateau region.
Figs. 1 and 2 show in detail the elevation spread of township
locations. In Fig. 1, townships with Chinese names have a unimodal
distribution that peaks around 2700 meters. Among these towns,
those with both Tibetan and Chinese names tend to be located at
higher altitudes, with the peak of the distribution at around
5
The current county boundaries of east and south regions of Tibetan Autonomous Region (TAR), and the broader Tibetan Autonomous Prefectures (TAP) are
primarily based on previous tribal borders, while those in the west are mainly
drawn from historical administrative borders of the central Lhasa government
before the Qing Dynasty. Historically, each county centered around a Dzong (fort),
and had a monk and Dzong-pon (civilian- Lhasa delegate administrator) to collect
taxes. Since a GIS map illustrating administrative boundaries of Chinese townships
was unavailable, the following approach was taken to calculate the area of each
township. The land area of each town was obtained by using Thiessen Polygon
feature in ArcGIS on township centroids. The features creates a border between two
adjacent towns by first calculating the map distance between two towns’ centroids,
and drawing a line through the point that is equidistant from both centroids.
Fig. 1. Number of towns with Chinese names.
3800 meters. No town with a Chinese name is located above
4600 meters, as shown clearly in Fig. 2. While most towns with
Chinese names are located in the lowlands at around 2700 meters
in altitude, towns with Tibetan names are generally located much
Fig. 2. Number of towns with Chinese names vs. Tibetan names.
C. Paik, T.W. Shawa / Applied Geography 40 (2013) 212e221
Fig. 3. Fraction covered by shrubs.
217
Fig. 4. Fraction covered by temperate forest.
higher up in altitude. In fact the highest number of Tibetan towns
found is at 4500 meters, and the distribution of Tibetan towns
shows a sharp decline only past 5200 meters. The bimodal spread
of these town locations suggests that there is a decreasing level of
Chinese presence in Tibetan ethnic regions as the elevation increases. For comparison, Maps 2 and 3 show the Tibetan plateau
and plot townships based on their geographic location coordinates.
In addition, Map 2 presents information on the ethnolinguistic
origin of township names, while Map 3 shows the fraction of Han
Chinese population in each township.
While we see a clear indication that the settlement pattern
diverged around 4500 meters, this divergence may also be a sign
of how the initial biogeographic setting (prior to first human
settlement) changed around this altitude. If there was a dramatic
change in biogeography over the same threshold to separate
agriculturalists from herders, the historical claim attributing the
source of ethnic division to altitude illness may not be the only
mechanism explaining the current settlement pattern. To illustrate whether this is the case, Map 4 first shows the vegetation
spread in Tibet. Fig. 3 shows that out of 1500 townships which
have the mean elevation below 4500 meters, 767 of them are
completely covered by shrubs. Furthermore, the majority of
these (1029 out of 1500) have more than half of the land
covered with shrubs. Shrubs continue to be the dominant
vegetation type above 4500 meters; 323 townships that are
above 4500 meters are completely covered by it, and the majority (428 out of 460) have more than 50 percent of the land
covered with shrubs. Fig. 4 clearly shows that most townships
above 4500 meters have less than half the land covered by
temperate forest. However, the majority of counties below
4500 meters also have less than half the land covered by
temperate forest as well. 384 counties above and 773 counties
below 4500 meters all have zero temperate forest coverage.
These figures suggest that the fraction of shrubs and temperate
forests, which together occupy 99 percent of the regions, show
very small changes in spread patterns around the altitude at
which there is a dramatic shift in town names. The threshold
seems therefore related to settlement choices due to altitude
illness, but not biogeography.
In Table 2, we introduce the indicator for historical Han presence as an intermediate variable, in line with our hypotheses. The
main purpose of this table is to check whether elevation mainly
affects current levels of prosperity through its impact on historical
Han presence, or if there is also a direct impact through the altitude illness argument as presented above. From Columns 1 and 2,
we see that the mean township elevation has a very strong
negative impact on the past Han presence, both with and without
the controls. For example, the coefficient value under Column 2
Table 2
Historical settlement and current Han population.
Variables
(1)
(2)
OLS (DV: historical presence)
Mean elevation
¼1 If historically
settled by Han
Controls
Constant
Observations
R-squared
0.273***
(0.015)
No
1.240***
(0.068)
1910
0.362
(3)
(4)
0.256***
(0.016)
Yes
1.110***
(0.334)
1910
0.389
(5)
(6)
OLS (DV: Han presence in 2000)
0.245***
(0.019)
No
0.026***
(0.003)
1660
0.364
0.207***
(0.019)
Yes
1.497***
(0.201)
1660
0.394
0.215***
(0.012)
No
0.933***
(0.053)
1709
0.416
Yes
0.606***
(0.214)
1709
0.447
Robust standard errors in parentheses.
***p < 0.01, **p < 0.05, *p < 0.1.
Controls include the township area, longitude and latitude, and a set of vegetation variables occupying the township.
All regressions include provincial dummies.
(8)
SUR
0.205***
(0.012)
Average causal mechanism effect
via historical Han presence
(7)
0.161***
(0.015)
0.142***
(0.015)
No
0.737***
(0.046)
1709
0.447
0.178***
(0.015)
0.124***
(0.011)
Yes
0.422 (0.441)
1709
0.447
0.041***
(0.006)
0.032***
(0.004)
218
C. Paik, T.W. Shawa / Applied Geography 40 (2013) 212e221
suggests that the likelihood of witnessing historical Han settlement in history decreases by roughly 26 percent as elevation increases by 1000 meters. Furthermore, when run alone, historical
Han presence has a strong negative impact on the current Han
concentration, as shown in Columns 3 and 4. The result indicates
that a township with Han heritage has 20 to 25 percent more Han
concentration today, depending on the regression specification.
Finally, the average effect of altitude on the level of current Han
presence is shown in columns 5 and 6, where we see that an increase in the township mean elevation by 1000 meters leads to a
20 point drop in the fraction of population identified as Han Chinese. However, when we do a mediation analysis as in columns 7
and 8, our results show that the mean elevation variable mainly
has a direct effect on Han presence that is independent of its
impact on historical settlement. The direct effect is in the magnitude of 0.16 and 0.18 under Column 8 respectively. This effect is
greater by 4e6 times the magnitude of the average causal mechanism effect. As the regression results show, the altitude effect is
robust to matching towns by location and biogeography. These
findings confirm that the historical settlement of Han Chinese
leads to more Han presence today, and that the channel through
which the elevation influences the population mainly runs
through altitude illness, rather than through its influence on the
historical settlement.
Conclusion
In this paper, we aim to show that both geography and historical settlement have long term impact on current population.
In particular, we discuss the various channels through which
altitude can influence the level of ethnic division today, and
present empirical evidence from Tibet’s unique landscape and
township name index. We find that the region’s high altitude has
determined the level of Han Chinese concentration both through
historical settlement and hypoxia. Even after controlling for
historical settlement, nature’s influence on physiology continues
to be heavily influential. The high altitude has proven to be a
daunting challenge for Han Chinese when trying to settle in the
region. In addition to influencing the local population’s culture
and lifestyle, Tibet’s formidable terrain appears to have essentially confined inter-ethnic relations mostly to the region’s
geographically defined borders. Today, the altitude influence
on the population is increasingly challenged as the Beijing
administration encourages more Han Chinese migration to
these regions. This is evident from the Great Development of the
West initiative beginning in the year 2000, when the central
administration started providing more infrastructure and
other economic incentives for the westward migration of Han
Chinese. The 2005 completion of the Qinghai-Tibetan Railway
also connected Tibetan regions to the rest of the country. Our
results in this paper nevertheless indicate that ethnic integration
in the face of natural barriers is never an easy process. Qi et al.,
(2009) for example reports that altitude illness continues to be a
severe problem for Han Chinese, in a study conducted on both
Han and Tibetan workers from the railway project. It appears
that as long as the townships do not relocate themselves down
from the highlands, ethnic integration may only take place
incrementally.
C. Paik, T.W. Shawa / Applied Geography 40 (2013) 212e221
219
220
C. Paik, T.W. Shawa / Applied Geography 40 (2013) 212e221
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.apgeog.2013.02.003.
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