AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 7059-73(1986)

Effect of Parental Consanguinity on Anthropometric Measurements Among the Sheikh Sunni Muslim Boys of Delhi

GOPAL KRISHAN Anthropological Survey of India, Udaipur, Rajasthan, India

KEY WORDS measurements, Muslim populations

Parental consanguinity effects, Anthropometric

ABSTRACT The study of consanguineous marriage is an efficient way to elucidate the genetic structure of human populations. Such matings give an opportunity for recessive genes to manifest themselves by becoming homozy- gous. The present attempt examines the effects of parental consanguinity on various anthropometric measurements among the Sheikh Sunni Muslim boys of old Delhi between the ages of 11 and 16 years. A slight inbreeding depression has been observed for all eight anthropometric measurements, i.e., stature, span, sitting height, head length, head circumference, chest girth, and calf circumference. The results support earlier studies in regard to the effect of consanguinity on anthropometric measurements.

Marriage regulates to a large extent the genetics of human populations, consequently affecting polygenic traits such as body mea- surements. The ambivalence of results per- taining to the effect of inbreeding on body measurements can be explained partly in terms of variation in the degree of consan- guinity and the selection of respective con- trols. Most authors agree that there exists a trend toward smaller body dimensions in the offspring bf consanguineous as compared to nonconsanguineous matings. Some studies reveal that the differences reach the level of statistical significance (F'urusho, 1961; Mor- ton, 1958); others do not find this (Ichiba, 1953; Shinozaki and Aoki, 1951; Shiroyama and Shiroyama, 1953; Shinozaki, 1955; Fu- jiki et al., 1968; Schull and Neel, 1965; Neel et al., 1970; Barrai et al., 1964; Mange, 1964; Schork, 1964).

The effects of inbreeding on various body measurements are different. For example, children from consanguineous marriages have significantly less muscular strength than their counterparts, i.e., children from nonconsanguineous ones (Ichiba, 1953; Shi- royama and Shiroyama, 1953). The present study investigates the effect of consanguinity on anthropometric measurements in an inbred population by comparing consanguin- eous and nonconsanguineous groups.

MATERIALS AND METHODS

Anthropometric measurements, i.e., stat- ure, span, sitting height, head length, head breadth, head circumference, chest girth, and calf circumference, were taken on 502 Sheikh Sunni Muslim boys aged 11-16 years from various schools in the walled city of Delhi. The measurements (recorded in millimeters) were taken following the methods of Martin and Saller (1957) and Tanner and associates (1969). The sample of 502 boys was divided into consanguineous and nonconsanguineous groups on the basis of genealogies. The de- gree of consanguinity was ascertained by in- terviewing the parents of each boy and deriving extended genealogies of at least three-generational depth. It was possible to trace the genealogies up to five generations in some cases. These genealogies were cross- checked by interviewing other elderly mem- bers of the family to reduce the chance of error.

RESULTS AND DISCUSSION

Sheikh Sunni Muslims of Delhi display a high level of parental consanguinity (36.45 %). First-cousin marriages are the most fre-

Received July 11.1985; revision accepted December 5,1985

0 1986 ALAN R. LISS. INC.

70 G. KRISHAN

quent type (23.90%); next in order of prepon- derance are one-and-one-half-cousin (7.17%) followed by second-cousin (5.38%) marriages. The frequency of parallel-cousin marriages (12.35%) is slightly higher than cross-cousin marriages (11.5%). The average coefficient of inbreeding among the Sheikh Sunni Mus- lims was found to be 0.017 (Krishan, 1981).

It is well known that socioeconomic factors other than parental consanguinity influence body dimensions. Therefore, it becomes im- perative to control or assess the effect of so- cioeconomic factors in order to study the effect of consanguinity. In the present study, father’s occupation, income, and education were taken as indicators of socioeconomic status. Comparison of consanguineous and nonconsanguineous groups revealed only mi- nor differences; a great deal of uniformity was observed in socioeconomic factors (Ta- ble 1).

The mean values of eight anthropometric measurements among the Sheikh Sunni Muslim boys between the ages of 11 and 16 years appear in Table 2. All the anthropo- metric measurements show a normal in- crease with age, as expected. Growth pattern between the two groups, i.e., among the off- spring of consanguineous and nonconsangui- neous matings, do not differ, as is evident from the age-group-wise analysis of the an- thropometric measurements.

Age-group-wise percentage mean differ- ences in eight anthropometric measure- ments between the consanguineous and nonconsanguineous groups have been calcu- lated using the following formula:

where xc is the mean of the anthropometric measurements in an a e group of the consan-

same anthropometric measurement in the same age group of the nonconsanguineous group. The percentage mean difference val- ues thus obtained are presented in Table 3 and are illustrated in Figure 1.

All eight anthropometric measurements in the age group 11-16 years show a trend to- ward decreased body size in the consanguin- eous group compared to the noncon- sanguineous. An analysis of the difference between the two groups by sign test reveals that the trend is significant; of a total of 48 comparisons (eight anthropometric measure- ments-in thgsix age groups) show negative sign (XC - XNC). This clearly demonstrates that consanguinity reduces body size. The reduction in body size cannot be attributed to socioeconomic factors in view of the negli- gible differences that exist between the con-

guineous group and # NC is the mean of the

TABLE 1. Percentage distribution of father’s occupation, income, and education among the Sheikh Sunni Muslims ofDelhi

Socioeconomic Nonconsanguineous concomitants Consanguineous group group Father’s occupation

Professional Administrative

executive and managerial

Clerical Minor business

Skilled worker

100-300

500-700

Illiterate Home-taught Primary school Middle school Matric.

high school

and sales worker

Father’s income (rupees)

300-500

Father’s education

5.64 4.23

26.26

32.39 30.98

38.25 39.25 22.50

9.09 27.28 9.09 9.09

36.36

3.86 1.94

23.30

36.89 33.99

40.00 40.00 20.00

8.33 33.33 8.33

16.33

25.00 Graduate 9.09 8.33

TAB

LE 2

. Dis

trib

utio

n of

mea

n an

d SE

M fo

r st

atur

e, s

pan,

sitt

ing

heig

ht,

head

bre

adth

, hea

d le

ngth

, hea

d ci

rcum

fere

nce,

che

st c

ircu

mfe

renc

e, a

nd c

alf

circ

umfe

renc

e am

ong

the

cons

angu

ineo

us a

nd n

onco

nsan

guin

eous

She

ikh

Sunn

i Mus

lims

of D

elhi

Hea

d C

alf

Age

N

o. o

f Si

tting

H

ead

Hea

d ci

rcum

fer-

C

hest

ci

rcum

- (i

n i n

divi

- St

atur

e Sp

an

heig

ht

brea

dth

leng

th

ence

gi

rth

fere

nce

year

s)

dual

s (m

m)

(mm

) (m

m)

(mm

) (m

m)

(mm

) (m

m)

(mm

)

Con

sang

uine

ous

11

30

1.36

0.80

1.

391.

86

712.

50

141.

55

177.

50

521.

30

651.

90

253.

23

~ . _.

~~

-8.7

6 k8

.76

k6.4

1 k0.84

k1.5

9 53

.07

k6.4

2 +

2.99

12

30

1,

462.

90

1,51

4.90

74

9.91

14

2.31

17

9.50

52

3.60

67

6.03

26

4.30

k 17

.00

k 10

.72

k0.0

6 k0

.59

k0.9

6 23

.67

k9.2

3 k5

.19

13

33

1,51

0.00

1,

52 1.

80

773.

42

143.

24

179.

64

525.

79

683.

64

274.

57

14

30

15

30

16

30

Non

cons

angu

ineo

us

11

45

12

46

13

65

14

65

15

51

16

47

k12.

71

1,52

0.84

15

.58

1,56

8.26

10

.42

1,61

2.50

k8

.95

1,39

3.88

+ 1

0.14

1,

501.

06

k12.

09

1,5 1

5.49

k 10

.66

1,56

5.64

k9

.80

1,59

4.47

+

9.38

1,

637.

21

-

+8.

90

k15.

67

+18

.46

1,57

6.33

1,63

0.60

k 10

.42

1,67

2.83

f 12

.27

1,41

1.75

k1

1.73

1,

526.

30

k12.

99

1,55

0.86

k1

1.66

1,

600.

15

+ 10.

66

1,65

6.41

f

10.6

4 1,

702.

74

k7.7

3

k8.1

0 77

5.86

f8

.50

803.

87

k7.7

6 83

1.10

k7

.04

724.

04

+0.

03

764.

34

f5.0

1 77

4.86

k3

.97

796.

30

k6.3

2 82

3.29

f7

.05

846.

27

k4.4

5

k0.1

7 14

3.53

k0

.76

144.

00

k0.7

6 14

4.10

k0

.85

142.

18

k0.6

6 14

3.63

f0

.59

144.

16

k0.5

7 14

4.46

+0

.54

145.

11

k0.7

6 14

5.68

k0

.76

k1.1

5 18

0.00

k1

.07

181.

06

kO.8

9 18

5.10

k0

.83

178.

08

181.

60

50.7

5 18

2.04

+

0.78

k0.7

2 18

3.39

k0.6

7

182.

23

k0.8

4 18

7.27

f0

.77

+5.

60

530.

23

k2.7

1 54

4.00

*2

.44

554.

13

k2.8

7

521.

57

k1.6

1 53

1.45

k2

.00

533.

67

5 1.

89

534.

44

k1.5

6 54

9.78

k2

.24

555.

57

k2.4

7

flO

.O1

705.

60

f9.8

7 73

6.60

+

5.63

76

6.23

k8

.62

652.

97

676.

63

f5.8

8 69

1.32

+

6.14

71

2.20

k5

.21

749.

11

f2.0

2 78

7.80

k7

.38

k4.2

1

k3.2

2 28

4.46

k2

.60

289.

96

k2.8

8 29

4.53

k3

.33

254.

22

k2.3

2 26

4.88

k2

.91

275.

33

f2.5

4 28

5.32

f2

.30

296.

41

52.5

2 30

3.21

f2

.42

72 G. KRISHAN

TABLE 3. Agegroupwise percentage mean differences between consanguineous and nonconsanguineous Sheikh Sunni Muslims in various anthropometric measurements

No. Head Calf Age Consan- Nonconsan- Sitting Head Head circum- Chest circum- (years) guineous guineous Stature Span height breadth length ference girth ference

11 30 45 -2.4 -1.4 -1.6 -0.4 -0.3 -0.00 -0.1 -0.1 12 30 46 -2.5 -0.8 -1.9 -0.9 -1.1 -1.4 -0.2 -0.8 13 33 65 -0.3 -1.8 -0.1 -0.6 -1.3 -1.4 -0.2 -1.1 14 30 65 -2.2 -1.4 -2.6 -0.6 -1.2 -0.7 -0.3 - 1.0 15 30 5 1 -2.5 -1.6 -2.3 -0.7 - 1.2 -1.0 -3.4 -1.1 16 30 47 -1.5 -2.5 -1.7 -1.0 -1.1 -0.2 -3.2 -2.7

‘. \

- STATURE - SPAN - - - -* SITTING HEIGHT --- HEAD BREADTH ... . . . HEAD LENGTH - - - HEAD CIRCUMFERENCE - - - CHEST GIRTH - - - C A L F CIRCUMFERENCE

PERCENTAGE M E A N D F ~ E R E N C E - -

WHERE - x - M E A N O F THE ANTHRWOW-

N C - E T R I C MEASURBMBNTS I N AN AGE C L A S S O F THP NOW- CONSANGUCNEOU$ 6RWC,

x c = M E A N O f THE ANTWROPW. -

15TlllC MEASUREMENTS IN AN A W C L A S S OF CONSANGUlNE6US ORWC

Fig. 1. Percentage mean differences between consanguineous and nonconsanguineous groups in various anthropometric measurements (age-group-wise).

EFFECT OF PARENTAL CONSANGUINITY ON ANTHROPOMETRIC MEASUREMENTS 73

sanguineous and nonconsanguineous groups (Table 1; Krishan, 1981).

The inbreeding depression observed here is in conformity with earlier studies concerned with the effect of consanguinity on anthro- pometric measurements such as reported by Morton (1958) on 8-10-month-old children, Ichiba (1953) on primary school children, Schull and Neel (1965) on children 5-11 years of age, Fujiki and associates (1968) on pri- mary school children, Neel and associates (1970) on 13-16-year-old children, and Mange (1964) and Barrai and associates (1964) on adult whites.

ACKNOWLEDGMENTS

The author is thankful to Prof. I.P. Singh of the Department of Anthropology, Univer- sity of Delhi, and Dr. S.K. Basu, Department of Population Genetics and Human Develop- ment, National Institute of Health and Fam- ily Welfare, New Delhi, for their suggestions in preparing this manuscript. I am also grateful to the Indian Council of Medical Re- search, Delhi, for providing financial assistance.

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