1During the 20th century, Bedouin groups throughout the Middle East have experienced rapid socio-cultural changes. In general, Bedouin mode of living has shifted from semi-nomad pastoralism toward more settled and more Western life style, and it is well established that such transitions are accompanied by considerable biological changes.
2In recent years, we witnessed the increasing frequency of reports concerning elevated blood pressure (hypertension), overweight, and other risk factors for life threatening morbidity across Bedouin populations all over the Middle East (Fraser et al., 1990; Paran et al., 1992; el Mugamer et al., 1995; Pilpel et al., 1995; Soyannow et al., 1997; al-Mahroos and al-Roomi, 1999; Jaddou et al., 2000). In face of this trend it is worthwhile to introduce some basic values of blood pressure and physique measured in a group of Bedouin tribes prior to substantial exposure to modernization agents.
3The population presented in this study is the Towara tribal affiliation, which inhabits the southern, mountainous region of the Sinai Peninsula. Geo-political circumstances have maintained this area in a relative isolation from Western influences, so that at the time of data collection, local economy was based on desert herding and other traditional sources of living such as palm tree cultivating, fishing, smuggling, some wage labor and international welfare (Marx, 1984). Institutions like high schools or hospitals were unavailable in the entire region, and for the majority of the 12,000 Towara Bedouins, running water, paved roads and electricity were novel (Kobyliansky and Hershkovitz, 1997).
4During the Israeli regime in the region between 1967-1982, the indigenous population has focused much scientific attention. Studies have documented the dietary intake of Towara Bedouins (Nir, 1985; Pervolotsky and Pervolotsky, 1979, cited by Kobyliansky and Hershkovitz, 1997; Pervolotsky, 1987), their genetic profile (Bonne, 1973) and anthropometric variation (Arensburg et al., 1979; Kobyliansky and Hershkovitz, 1997, 2002; Monk et al., 2000). However, studies concerning the physiology of the Towara population have not been published.
5The aim of the present study is to present values of blood pressure and related traits in a traditional, pre-modernized Bedouin society. These data might serve as a reference for comparison with corresponding values in different stages of modernization.
6The data presented here originate in a comprehensive field survey carried out in South Sinai during 1978-1980 by the staff of the Department of Anatomy and Anthropology, Sackler School of Medicine, Tel Aviv University (See Arensburg et al., 1979; Kobyliansky and Hershkovitz, 1997, 2002).
7The sample included 318 Bedouin males and 91 Bedouin females, aged 17-85 years. Female’s samples are smaller due to high sensitivity of the Bedouin society to physical examination of women.
8Physiologic and anthropometric traits were measured according to standard procedures (see Kobyliansky and Hershkovitz, 1997). Rate of hypertension was calculated as percentage of persons with systolic blood pressure of 140 mmHg and over, andor diastolic values of 90 mmHg and over. Samples of the two largest Towara tribes (Muzeina and Gebelia) are considered separately, while samples of the smaller tribes had to be pooled together to form units sufficient for statistical analysis. Female samples from all Towara tribes other than Gebelia and Muzeina were gathered to form the Other Towara sample. The larger male samples allowed differentiation of an additional tribal group: Aleigat and Hamada, a couple of biologically and geographically related tribes.
9Male members of all smaller tribes (Gararshe, Sawalha, Bani-Wasel, Awlad-Said, Hweitat and Ahali-A-Tur) comprise the Other Towara sample.
10Data are presented according to age groups. Once again, male samples allow better resolution, while female samples, even when divided to 3 age groups are minute.
11In order to reduce the variability stemming from age dependant factors, inter-tribal variation is evaluated by comparing means of the relatively homogenous age groups of young adults: 20-39 years in males, and 17-39 years in females (females mature earlier, thus late teenagers are supposed to reach their adult values, as opposed to males whose growth continue throughout the 2nd decade of life).
12A one-way analysis of variance was carried out for subdivisions of age groups and tribal affiliation. Scheffe’s multiple range test was applied to determine separability of subgroups’ means.
13Some comparative data of neighbouring Bedouin and other Arab groups, as well as reference European group are presented for estimation of the relative position of Towara males and females.
14Tribal differences among Towara people are considered for the relatively homogenous age group of young adults (20-39 years for males, 17-39 years for females, tabl. 1,2). Mean systolic and diastolic values of males in four tribal groups range from 117 to 125 mmHg, and from 79 to 86, respectively, with some inter-tribal differences: Gebelia men, residing in the high mountain region, have the highest mean systolic pressure and the highest rate of hypertension, while at the same time their mean diastolic pressure is lowest (tabl. 1).
15Mean BMI of all 4 male groups is very close to 20, ranging from 19.7 to 20.4, with no significant inter-tribal differences (tabl. 1). Female range is larger: 18.9-22.2, with mean BMI of Muzeina being significantly lowest (tabl. 2). For the traits related to blood pressure, Muzeina females essentially constitute the entire Towara sample, with exceptionally low values of blood pressure (108/76). Rate of hypertension of Muzeina females aged 17-39 is close to 4% (tab. 2).
Tabl. 1 - Sample sizes (n), means, standard deviations (sd) and ANOVA results (p) for blood pressure (BP) values and anthropometric traits of Bedouin males, age 20-39 in 4 subgroups of Towara tribal affiliation, Sinai Peninsula.
Tabl. 2 - Sample sizes (n), means, standard deviations (sd) and ANOVA results (p) for blood pressure (BP) values and anthropometric traits of Bedouin females, age 17-39 in 3 subgroups of Towara tribal affiliation, Sinai Peninsula.
* Percent of cases with blood pressure values >/= 140 and/or >/= 90 mmHg.
n.s. – not statistically significant (p>0.05)
BP – Blood pressure (mmHg)
SF – Skin fold thickness (mm)
BMI – Body mass index (kg/m2)
19When compared to other groups of Arabs living in neighbouring countries, Towara Bedouins have low blood pressure values (fig. 1,2) and low rates of hypertension (fig. 3,4).
Fig. 1 - Mean systolic and diastolic blood pressure values (in mmHg) of 4 female groups, ordered from lowest to highest systolic pressure.
Fig. 2 - Mean systolic and diastolic blood pressure values (in mmHg) of 5 male groups, ordered from lowest to highest systolic pressure.
Fig. 3 - Rate of male and female hypertension (defined as blood pressure >/= 140/90 mmHg) in 3 neighbouring Arab groups.
Fig. 4 - Rate of hypertension (defined as blood pressure >/=160/95 mmHg) in 4 Bedouin groups.
21Tables 3-4 display data of Towara male and female (respectively) according to age groups and regardless of tribal origin. Among males, for all traits the mean values at 20-39 years are higher than those at 17-19 years, but this age-dependent increase continues throughout the age range only for BMI and Triceps skin-fold thickness. The highest mean blood pressure (125/86) and the highest hypertension rate (18.8%), belongs to the oldest group (50+), although Scheffe’s multiple range test does not support the separability of means for blood pressure. Female samples are small, indicating agedependent increase in most traits. Mean blood pressure of the oldest group (40+) is 117/81 and values of the youngest group (17-19 years) are 107/74, however none of the differences reach the level of statistical significance, probably due to the small samples of the youngest and oldest age groups.
Tabl. 3 - Sample sizes (n), means, standard deviations (sd) and ANOVA results (p) for blood pressure (BP) values and anthropometric traits of Towara Bedouin males by age groups (years).
Tabl. 4 - Sample sizes (n), means, standard deviations (sd) and ANOVA results (p) for blood pressure values and anthropometric traits of Towara Bedouin females by age groups (years).
* Percent of cases with blood pressure values >/= 140 and/or >/= 90 mmHg
n.s. – not statistically significant (p>0.05)
BP – Blood pressure (mmHg)
SF – Skin fold thickness (mm)
BMI – Body mass index (kg/m2)
24Towara Bedouins have been dwelling in the Southern region of the Sinai Peninsula for many generations. In fact, these semi-nomad tribes are the only permanent inhabitants of this desolated region (Marx, 1984; Kobyliansky and Hershkovitz, 1997, 2002).
25Low values of blood pressure and body mass are documented in the present study for various segments of the Towara population. Mean values of systolic blood pressure for men of all tribal groups and of all age groups range between 115-125 mmHg, and diastolic values between 78-85 mmHg. Females’ mean values are even lower: 107-120 and 74-80 for systolic and diastolic values, respectively. The overall hypertension rates are 12% for males and 4% for females. Mean BMI range between 18-22 kg/m2 in both sexes. These values are typical to tribal, pre-modernized populations (Pauletto et al., 1994, 1996; Kaufman et al., 1999), yet our findings are in contrast to many recent reports of Bedouin groups throughout the Middle East.
26Starting in the early 1990s there is a widening stream of publications concerning high prevalence of hypertension and obesity among Bedouins at various stages of the modernization process from Israel (Fraser et al., 1990; Paran et al., 1992; Pilpel et al., 1995), Jordan (Jaddou et al., 2000), Saudi Arabia (Soyannow et al., 1997), the United Arab Emirate (el Mugamer et al., 1995), and additional regions of the Arabian Peninsula (al-Mahroos and al-Roomi, 1999). The findings of increased body mass and blood pressure among Bedouins is said to reflect the rapid transition experienced by these populations along the 20th century, moving from semi-nomadic pastoralist subsistence to a more Western mode of life.
27Although modernization has affected the entire Middle East, some Bedouin groups were influenced to a large extent while others were minimally exposed, and this can be expressed in the distribution of blood pressure values. The southern region of the Sinai Peninsula is clearly an area that remained peripheral to major geo-political and sociocultural changes. Our data were obtained in the late 1970s, when South Sinai was to a great extent isolated from the Western world. Paved roads, running water and electricity had just been introduced to the region. Reports of the diet of contemporaneous Towara Bedouins can shed some light over the low values of blood pressure, as they reveal poor intake of carbohydrates, fat, and sodium, besides low intake of proteins (Nir, 1985; Pervolotsky and Pervolotsky, 1979, cited by Kobyliansky and Hershkovitz, 1997; Pervolotsky, 1987).
28It has been shown elsewhere that despite the poor living conditions of Towara Bedouins, gradual exposure to agents of the Western world did occur, and Towara men demonstrated secular increase in stature along the 20th century (Field, 1952; Monk et al., 2000). The issue of secular trend among Towara women is less clear, for lack of earlier reports of their physique. We inferred a considerable delay in the exposure of Towara women to improved environmental conditions (Monk et al., 2000).
29Regarding blood pressure and body mass of the Towara population, we have no earlier data for comparison, and we can only assess them in relation to other groups. The closest groups available for comparison are 2 samples of male Bedouins from the Israeli Negev studied during 1985-1986 (Fraser et al., 1990). The samples are differentiated by their life style, defined as “settled” versus “tribal”. Mean blood pressure values of the 2 groups are similar (131/80 vs. 132/82), despite significantly higher mean BMI of the former (25 vs. 23), and lower hypertension rate of the later (18.2 vs. 14.8). The authors report increase in ischaemic heart diseases among Negev Bedouins, starting in the 1970s (Fraser et al., 1990). Mean systolic value as well as mean BMI in both Negev groups are higher than any of the mean values recorded among Towara subgroups.
30Another source for comparison is the Egyptian National Hypertension Project carried out in the early 1990s, where blood pressure values of both men and women are close to 120/80 for the age range of 25-44 years, and approach 130/80 for age 45-54 years (Ibrahim et al., 1995, Ibrahim, 1996). Blood pressure values of Towara men are quite similar to those of the general Egyptian population, however, blood pressure distribution in the present study is rather different in at least three ways: first, blood pressure of Towara women is considerably lower than their male counterparts, and second, there is no clear age related increase in blood pressure. The third and most prominent difference concerns the rate of hypertension, which exceeds 25% in the Egyptian population. Similar rates were reported for a Saudi population (Soyannow et al., 1997) and for Arab Israelis (Amad et al., 1996), as opposed to Towara Bedouins, with less than 5% female hypertension, and less than 13% male hypertension.
31These three characteristics of blood pressure variation, namely distinct sex dimorphism, blurred age increments, and low hypertension rates, further indicate the traditional nature of the studied population (Dressler, 1999; Gerber and Stern, 1999; Stevenson, 1999).
32To conclude, the present study examines blood pressure variation in a traditional, pre-modernized semi-nomad Bedouin group of tribes, inhabiting a desolated region of the Sinai Peninsula. The low level of blood pressure values and hypertension rates recorded in the Towara population, attest to the minimal amount of exposure to modern lifestyle.