SOCIAL NETWORKS, SUPPORT CLIQUES, AND KINSHIP R. I. M. D u n b a r

M. Spoors

University of Liverpool

University College London

Data on the n u m b e r of adults that an i n d i v i d u a l contacts at least once a m o n t h i n a set of British p o p u l a t i o n s yield estimates of n e t w o r k sizes that correspond closely to those of the typical " s y m p a t h y group" size in h u m a n s . M e n and w o m e n do not differ i n their total n e t w o r k size, b u t w o m e n have more females a n d more k i n in their n e t w o r k s than m e n do. K i n account for a s i g n i f i c a n t l y higher p r o p o r t i o n of network m e m b e r s than w o u l d be expected b y chance. The n u m b e r of k i n in the n e t w o r k increases in p r o p o r t i o n to the size of the family; as a result, people from large families have proportionately fewer n o n - k i n in their networks, suggesting that there is either a time constraint or a cognitive constraint on n e t w o r k size. A small i n n e r clique of the network functions as a support group from w h o m an i n d i v i d u a l is particularly likely to seek advice or assistance in time of need. K i n do not account for a significantly higher p r o p o r t i o n of the support clique t h a n they do for the wider network of regular social contacts for either m e n or w o m e n , b u t each sex exhibits a strong preference for m e m b e r s of their o w n sex.

KEY WORDS: Networks; K i n s h i p ; Sex differences; Family size;

Support group.

Received August 22, 1994; accepted January 23, 1995.

Address all correspondence to R. I. M. Dunbar, Department of Psychology, University of Liverpool, P. O. Box 147, Liverpool L69 3BX, England. Copyright 9 1995 by Walter de Gruyter, Inc. New York Human Nature, Vol. 6, No. 3, pp. 273-290. 273

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There has been considerable interest in both the sociological and the anthropological literatures regarding the people with w h o m individuals interact. The current view emphasizes the fact that an individual lies at the focal point of a number of partially overlapping social networks, each of which is oriented towards a different social context or purpose (Milardo 1988). Thus, an individual m a y have a number of different sets of friends based on work, leisure activities (such as an interest group or sports club), church, the extended family, and so on. Moreover, the pattern of relationships may change over an individual's lifetime (Larson and Bradney 1988). It is clear, however, that there are limits to the number of contacts that an individual can maintain over a given period of time. "Small world" experiments in which individuals are asked to send messages to distant parts of the world via a chain of contacts rooted in their circle of personal acquaintances suggest that the number of people on whom any one individual can call for such favors is limited to between 130 and 250 (Killworth et al. 1984). This estimate of the size of an individual's social world is on the same order as that estimated from the size of the modern human neocortex based on a relationship between neocortex size and group size derived from primates (Dunbar 1993). Many of these individuals, however, are likely to be acquaintances rather than intimate friends. It is widely recognized that this inner circle of more intense relationships plays a crucial role in mediating the individual's interactions with (and place within) the local community (Bott 1971; Milardo, ed. 1988; Mitchell 1969; Young and Willmott 1957). Estimates of the size of this inner circle (the so-called sympathy group) have yielded values on the order of 10-12 individuals (Buys and Larsen 1979). In this case, the estimates were obtained by asking individuals to list all the people whose death they would find personally devastating, but they probably correspond to those people with w h o m an individual keeps in regular contact. Network sizes estimated from frequency of contact have yielded values ranging from seven in U.S. college freshmen (Hays and Oxley 1986) to 16.6 in young w o m e n (McCannell 1988) and around 20 in married couples (Rands 1988). Differences in both the criteria used to define network membership and the stages of the life cycle at which networks are sampled are largely responsible for the differences found between studies. Nonetheless, it is clear that all these values tend to converge on the same group size (10-15 individuals). One reason for our interest in the size of these groupings derives from the suggestion that language may have evolved to allow the exchange of social information in order to facilitate the integration of relatively

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large social groups (Dunbar 1993). There is some evidence to suggest that the constraints in this respect derive not so much from the ability to monitor all individuals in the community but rather from the need to monitor the activities and doings of one's key social allies (principally, presumably, one's family and immediate friends) (Kudo et al. 1995). One aim of this study, then, was to try to determine the size and composition of the inner circle (or network) that might constitute the focus of an individual's social interest. Kinship is known to play an important role in both h u m a n social relationships and the structure of h u m a n groups in traditional as well as modern postindustrial societies (see, for example, Firth 1956; Hughes 1988; Keesing 1975). Hames (1979) has shown that Ye'kwana villagers of Venezuela interact more often with individuals who are closely related to them, while Bert6 (1988) found that among the horticultural K'ekchi" of Central America the availability of a network of kin is an important determinant of the amount of land an individual can cultivate. The extent to which kinship is a consideration in the creation of social networks in industrial societies remains unclear, however, even though interview-based studies suggest that considerable weight is placed on kinship in contemporary European societies (Bott 1971; Young and Willmott 1957). We examine here the role that kinship plays in determining the composition of an individual's social network in a modern European society. Our main concern is with the circle of friends and relations with whom an individual maintains regular contact. Given that we can identify such a group, we can then ask what role kinship plays in determining its composition. In addition, we examine the size and composition of the inner clique of intimates (the support clique) that individuals would normally approach for advice or assistance when in difficulty. We might expect kinship to be an important factor in the selection of support clique members because the opportunity for reciprocal altruism is likely to be much less in situations of advice a n d / o r help than it is with respect to social interaction. Studies of social networks have tended to focus either on quantitative analyses of network size and structure (Burt 1982; Coleman 1964; Knoke and Kuklinski 1982) or on more descriptive studies of individuals' networks and their role in facilitating social life (Bott 1971; Fischer 1982; studies in Mitchell, ed. 1969 and Milardo, ed. 1988). In general, the more quantitative studies have typically concerned themselves with largescale structures at the societal level, often with a focus on organizations rather than individuals (e.g., business and political networks) and the functional roles that exist within organizations of this kind. In contrast, studies of personal and support networks have tended to be based on

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in-depth interviews with a handful of individuals, with the focus on how individuals relate to their immediate social circles. Our aim here is to provide a preliminary assessment of the size of an individual's network of intimates and the extent to which kin contribute to it.

METHODS

A questionnaire was designed which asked respondents to list the first names of individuals whom they (a) lived with, (b) contacted with varying degrees of frequency (termed their network), and (c) relied on for advice a n d / o r help at the personal level (termed the support clique), as well as (d) the size of their extended biological family (defined as all individuals related to the subject by r > 0.125, assuming full paternity certainty). Contacts were defined as social exchanges involving face-to-face, letter, or telephone interaction. Respondents were specifically asked not to include business and professional contacts, unless the individuals concerned were deemed to be personal friends. In responding to (a)-(c), subjects were required to distinguish between relatives and nonrelatives, with the criterion for a relative being limited to full cousins or more closely related individuals. Subjects were asked to list the first names of individuals they contacted daily, twice weekly, weekly, and at least once a month, as well as those individuals they contacted regularly but less than once a month. Considerable effort has been put into questionnaire design during the past decade (see Milardo 1988, and references therein). The burden of this work has been to suggest that questionnaires that take more than a few minutes to complete and have too many instructions a n d / o r more than 10-12 name-eticiting questions tend to result in loss of concentration. The questionnaire was therefore designed to contain just four sets of questions, each accompanied by a series of boxes to be filled in. The questionnaire was tested on students and refined until it required no more than 5 minutes to complete. The questionnaire design used a recall procedure rather than asking individuals to list all those whom they actually contacted during a set period of time from receipt of the questionnaire. This approach was largely chosen for speed and convenience. Although recall procedures run a risk that respondents will overlook contacts they have made (see Bernard et al. 1982, 1984), the relatively short time depth used in the present case should tend to minimize this source of inaccuracy. In contrast, prospective questionnaires greatly increase the load on the subject because they require respondents to keep a daily tally of w h o m they have contacted; as a result, under-reporting by those who lead especially busy lives tends to increase. In addition, they tend to underestimate the

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actual network size because individuals may not always be able to contact all their normal interactees during a particular sample period (e.g., because they are away or other unusual circumstances intervene). In order to try to circumvent some of these problems, subjects were asked to say whom they normally contacted during a given time period. It was felt that this would reduce both errors of omission and the number of trivial contacts listed (i.e., those casual contacts who were not members of the respondent's circle of friends). Questionnaires were distributed at five different locations within England and Scotland. These respondents were not chosen to be a representative sample in any conventional sense, but simply to provide a broad sample of subjects of different age, background, and geographical location. In each case, a single assistant was responsible for handing out and collecting completed questionnaires. Each assistant was instructed to tell respondents only that the purpose of the questionnaire was to find out about people's social contacts. They were, however, allowed to help with the filling in of questionnaires if requested to do so. Questionnaires were distributed only to subjects between 18 and 65 years of age who were members of a golf club or staff at a hospital in Lincolnshire, staff at an employment consultancy in Aberdeen, employees at a farm machinery factory in Doncaster, and personal contacts within the London area. With just a few exceptions, only one respondent was sampled per household. Individuals over 65 years of age were excluded from the sample because they are known to have reduced network sizes owing to greater vulnerability to infirmity as well as deaths among lifelong friends (Bliezner 1988; Brown 1981). Similarly, children and younger teenagers were excluded because their networks are known to be atypical in both composition and stability (Foot et al_ 1980; Levinger and Levinger 1986; Thorne 1986). A total of 155 questionnaires were returned from the 170 given out. The resulting response rate of 91% is high by normal questionnaire standards and can largely be attributed to the fact that in most cases the subjects were themselves known to the assistants distributing the questionnaires. Personal loyalty is thus likely to have been an important factor influencing the completion of questionnaires. Of the returned questionnaires, 54 were excluded from the analysis: the majority had been incompletely (or in a few cases, incorrectly) filled in (mostly failure to identify contacts by sex), but 11 were spoiled in transit or otherwise unreadable and 8 contained too many comments and queries to be considered reliable. So far as we could tell, incomplete and spoiled questionnaires were not biased in favor of any particular category of subject by sex, age, or domestic status. The remaining 101 subjects consisted of 34 men and 67 women. Of these, 24.8% (5 men and 20 women) were single, 50.5% (18 men and 33 women) lived with a partner but did not

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have d e p e n d e n t offspring living with them, 21.8% (9 m e n and 13 w o m e n ) lived with a partner and d e p e n d e n t children, and two w o m e n lived alone with d e p e n d e n t children. O u r concern was to identify the set of p r i m a r y associates ("friends" in the normal meaning of the term) that an individual has. This is the set of p e o p l e w h o s e activities and life histories are of sufficient interest to an individual for that person to be willing to m a k e some effort to keep u p to date. Rather than ask r e s p o n d e n t s to specify these individuals using their o w n criteria, w e preferred to use a m o r e objective criterion that could be applied u n i f o r m l y across the entire sample. The n u m b e r of contacts was bimodal, with peaks in the w e e k l y and m o n t h l y frequency categories. We therefore used the f r e q u e n c y with which individuals were contacted on at least a m o n t h l y basis as the criterion for inclusion in a subject's network. We took the view that individuals w h o contacted each other less often than once a m o n t h w e r e unlikely to remain u p to date with each other's m o r e intimate experiences, and thus fell outside the scope of the present concern. All statistical tests are two-tailed. Data w e r e log-transformed in o r d e r to normalize values for all parametric statistical analyses.

RESULTS Network Size and Composition Figure 1 shows the distribution of n e t w o r k sizes in the sample. The m e a n n e t w o r k size for all subjects was II.6 (range 0-30, sd = 5.64; N = 101). The distribution exhibits some d e g r e e of bimodaiity, with peaks at n e t w o r k sizes of 6 and 11-12, suggesting that it m a y be possible to distinguish between more- and less-sociable individuals. Before w e can safely d r a w this conclusion, however, w e need to check that the bimodality is not due to c o n f o u n d i n g variables such as g e n d e r or domestic circumstances. There was a slight, but nonsignificant, g e n d e r difference in n e t w o r k size: w o m e n averaged a n e t w o r k of 12.4 individuals (N = 67) c o m p a r e d with 10.9 (N = 34) for m e n ( M a n n - W h i t n e y test, z = -1.006, P -- 0.315). This is largely a consequence of the fact that the distribution of n e t w o r k sizes for w o m e n was more s k e w e d (longer tail to right) than that for the men. Modal n e t w o r k size was v e r y similar for the two sexes. As might be anticipated, the domestic status of subjects did h a v e some influence on their n e t w o r k size. Single subjects had a m e a n netw o r k size of 15.4 (range 7-30, sd = 6.20; N = 25), c o m p a r e d with m e a n s of 11.1 (range 0-25, sd = 5.55; N = 51) for couples w i t h o u t children at

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Network size Figure 1. Distribution of network sizes. home and 8.7 (range 0-19, sd = 4.16; N = 24) for couples with d e p e n d e n t children (including the two single mothers). However, the variance within each category was considerable, and the differences between them were not significant (Mann-Whitney tests: singles vs couples without children, z = 0.99, P = 0.322; couples without children vs couples with children, z = 1.48, P = 0.139). For all three distributions, however, the same pattern is evident: 40.0% of singles had networks of size 6-12 compared with 66.7% of couples both with and without d e p e n d e n t children. The differences are largely in the lengths of the tails on either side of the modal values. Singles had a truncated lower range, whereas couples with children had a truncated u p p e r range, while couples with no dependent children had a more even distribution. We examined gender differences in the composition of the network using a MANOVA with respondent's gender as the i ndependent variable and the proportions of contacts that were male (as opposed to female) and kin (as opposed to non-kin) as the dependent variables. (For these purposes, kin were defined as individuals related to the subject by r > 0.125.) This examination revealed that the two sexes differed significantly in terms of the ratio of male to female contacts (mean percent of

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n e t w o r k m e m b e r s that w e r e male: 67.7% for m e n a n d 30.8% for w o m e n ; F1,94 = 47.75, P < 0.001), n u m b e r of f e m a l e kin contacted ( m e a n s of 1.88 for m e n a n d 3.06 for w o m e n : F1,94 = 9.64, P = 0.002), n u m b e r of m a l e non-kin contacted (means of 5.62 for m e n a n d 1.75 for w o m e n : F1,94 = 52.81, P < 0.001), a n d n u m b e r of f e m a l e n o n - k i n contacted ( m e a n s of 1.65 for m e n a n d 5.51 for w o m e n : F1,94 = 57.97, P < 0.001), b u t not in t e r m s of the n u m b e r of m a l e kin contacted ( m e a n s of 1.74 for m e n a n d 2.06 for w o m e n : F1,94 = 0.14, P = 0.705). In s u m m a r y , w o m e n h a d a larger n u m b e r of female friends a n d relatives in their n e t w o r k s , w h e r e a s m e n h a d a larger n u m b e r of m a l e friends, w i t h kin b e i n g significantly less i m p o r t a n t for m e n than for w o m e n . There w e r e no differences in the n u m b e r of n o n - k i n contacted m o n t h l y (means of 7.26 for m e n a n d 7.25 for w o m e n ) , or in the p r o p o r tion of n o n - k i n contacted at least once a m o n t h w h o w e r e contacted at least once a w e e k (means of 39.3% for m e n a n d 43.9% for w o m e n : M a n n W h i t n e y test, z = 0.99, P = 0.327). H o w e v e r , there w a s a significant difference in the p r o p o r t i o n of all m o n t h l y n o n - k i n m a l e contacts that w e r e contacted at least w e e k l y (means of 81.4% for m e n a n d 22.8% for w o m e n : M a n n - W h i t n e y test, z = --4.78, P < 0.001). There w a s no difference b e t w e e n the sexes in the p r o p o r t i o n of their e x t e n d e d families (defined as the total n u m b e r of living i n d i v i d u a l s related to the subject b y r > 0.125) w h o w e r e c o n t a c t e d m o n t h l y ( m e a n s of 29.9% out of an a v e r a g e family of 12.1 m e m b e r s for m e n a n d 36.3% out of an a v e r a g e family of 14.1 for w o m e n : M a n n - W h i t n e y test, z = 0.18, P = 0.857). A l t h o u g h m e n d i d not contact m o r e m a l e kin t h a n w o m e n did in absolute terms, they did contact a h i g h e r p r o p o r t i o n of the m a l e s in their e x t e n d e d families t h a n w o m e n d i d ( m e a n s of 48.8% of 3.6 m a l e kin for m e n vs 40.2% of 5.1 m a l e kin for w o m e n ; M a n n W h i t n e y test, z = -2.67, P = 0.008). Overall, kin accounted for 37.5% of the n e t w o r k , a figure that is almost certainly significantly higher t h a n w o u l d be e x p e c t e d if p e o p l e chose their n e t w o r k m e m b e r s at r a n d o m either f r o m the local p o p u l a tion as a w h o l e or f r o m the s u b s a m p l e of that p o p u l a t i o n w h o m t h e y k n o w b y sight. Unfortunately, w e c a n n o t test the significance of this because w e do not h a v e a n y a p p r o p r i a t e v a l u e s to u s e for the null hypothesis. Nonetheless, kin are likely to account for a relatively small p r o p o r t i o n of all the individuals that a n y o n e p e r s o n k n o w s . If w e take the l o w e r m o r e c o n s e r v a t i v e figure of 150 a c q u a i n t a n c e s f r o m the " s m a l l w o r l d " e x p e r i m e n t s (Killworth et al. 1984) a n d the a v e r a g e e x t e n d e d family size obtained in this s t u d y of 12.1 for m e n a n d 14.1 for w o m e n (see above), w e w o u l d expect only a b o u t 8.1% a n d 9.4%, respectively, of n e t w o r k m e m b e r s to be kin if chosen at r a n d o m . O n this basis, the o b s e r v e d p r o p o r t i o n is clearly significantly biased in f a v o r of kin for

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both sexes: the p r o p o r t i o n of kin in the n e t w o r k is greater t h a n the expected v a l u e for 32/34 m e n (;(2 = 26.47, df = 1, P < 0.001) a n d for 63/66 w o m e n (one w o m a n w i t h a n e t w o r k size of 0 w a s e x c l u d e d ) (X2 = 54.55, df = 1, P < 0.001).

Network Size and Kin Group Size If the n u m b e r of individuals w h o can be m a i n t a i n e d in a close social n e t w o r k is limited either b y the t i m e available for interaction (e.g., D u n bar 1992) or b y constraints i m p o s e d b y the p r o c e s s i n g c a p a c i t y of the cognitive m a c h i n e r y (e.g., D u n b a r 1993), t h e n w e m i g h t expect there to be an inverse relationship b e t w e e n total n e t w o r k size a n d the size of the family. In other words, individuals w h o h a v e large e x t e n d e d families m a y be m o r e likely to confine their social contacts to m e m b e r s of their family circle than are those i n d i v i d u a l s w i t h f e w e r close relatives to choose from. Figure 2 suggests that there is a w e a k n e g a t i v e relationship b e t w e e n the n u m b e r s of kin a n d non-kin contacted at least m o n t h l y ( P e a r s o n ' s r = -0.138, t99 = 1.37, P > 0.05). O n e likely reason w h y the correlation is

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p o o r is the large n u m b e r of individuals in the l o w e r left q u a d r a n t (who contact only a small n u m b e r of both kin and non-kin). In other w o r d s , it m a y be that for relatively asocial individuals w h o s e n e t w o r k size is well below the cognitive limit, the n u m b e r of kin does not restrict the n u m b e r of non-kin contacted. If all subjects w h o contacted f e w e r than 10 individuals are excluded, then there is a highly significant negative correlation b e t w e e n n u m b e r s of kin a n d non-kin contacted (r = -0.554, t58 = -5.06, P < 0.001). One reason for this seems to be that individuals from large families tend to contact more kin (Figure 3: Pearson's r = 0.397, t99 = 4.30, P < 0.001). In contrast, the n u m b e r of non-kin contacted is not significantly related to the size of the family (Figure 4: r = -0.032, t80 = -0.32, P > 0.05; for subjects with networks larger than nine members: r = -0.096, t58 = -0.74, P > 0.05); rather, it m a y be related m o r e closely to individuals' respective opportunities for interaction outside the family. These results suggest that p e o p l e place a p r e m i u m on m a i n t a i n i n g family contacts and only extend their n e t w o r k of contacts b e y o n d the family if they have spare capacity in their total n e t w o r k size once their key family contacts have been exhausted. This seems to be i n d e p e n d e n t

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Family size Figure 4. Number of non-kin contacted at least once a month plotted against total family size. of the distribution of degrees of kinship within the family (i.e., kinship density): n u m b e r of kin contacted is not related to subject's m e a n d e g r e e of relatedness, rmean, to all the m e m b e r s of h i s / h e r e x t e n d e d family (Pearson's r = 0.092, F1,99 = 0.47, P = 0.496). In other words, families with a higher p r o p o r t i o n of closely related individuals (e.g., siblings) d o not s h o w any t e n d e n c y to interact m o r e frequently w i t h each other t h a n those with a lower p r o p o r t i o n (e.g., f e w e r siblings, m o r e cousins). Note, however, that individuals d o not necessarily interact with all the m e m bers of their extended family. On average, m e n contacted o n l y 30.0% of the m e m b e r s of their extended family at least once a m o n t h , while w o m e n contacted 36.6% of their family members.

Kinship and the Support Clique The m e a n n u m b e r of individuals from w h o m s u p p o r t sought was 4.72 (range 0-14, sd = 2.95; N = 101). There was ence in the sizes of the s u p p o r t cliques of m e n and w o m e n 4.47 for 34 m e n and 4.85 for 67 w o m e n ; M a n n - W h i t n e y test,

w o u l d be no differ(means of z = -1.18,

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P = 0.236). Figure 5 suggests that, as w i t h the n e t w o r k size, the distribution is b i m o d a l with p e a k s at 2-3 a n d 5. D i s a g g r e g a t i o n of the d a t a for m e n a n d w o m e n yields a similar picture, b u t w i t h slightly offset peaks: m e n at 2 a n d 5, w o m e n at 3 a n d 7. As w i t h the distribution of n e t w o r k sizes, the p e a k s in the size of the s u p p o r t clique m a y c o r r e s p o n d to contrasts b e t w e e n m o r e - a n d less-sociable individuals. S o m e e v i d e n c e to s u p p o r t this suggestion comes f r o m the fact that the size of the s u p p o r t clique is linearly related to total n e t w o r k size (Figure 6: P e a r s o n ' s r = 0.427, t97 = 4.651, P < 0.001) a n d represents an a v e r a g e of 39.8% of the individual's total contact n e t w o r k . There s e e m to be no c o n s p i c u o u s differences b e t w e e n the sexes in this respect. Of the s u p p o r t clique, 22.6% w e r e typically f e m a l e kin, 33.5% f e m a l e non-kin, 17.1% m a l e kin, a n d 26.8% m a l e non-kin. The p r o p o r t i o n of s u p p o r t sources that w e r e kin d o e s not differ f r o m the p r o p o r t i o n of total m o n t h l y contacts (i.e., n e t w o r k size) that w e r e kin (Wilcoxon m a t c h e d pairs tests: for men, z = --0.18, P = 0.860; for w o m e n , z = -0.62, P = 0.536); n o r does the p r o p o r t i o n of the s u p p o r t clique that w a s of the o p p o s i t e sex differ f r o m the p r o p o r t i o n in the total n e t w o r k (Wilcoxon tests: for men, z = -1.172, P = 0.086; for w o m e n , z -- -1.91, P = 0.056). This sug-

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Network size Figure 6. Support clique size plotted against total network size. gests that, overall, the s u p p o r t clique is chosen on the s a m e basis as the w i d e r n e t w o r k of friends, a n d it a p p e a r s to be a m o r e or less r a n d o m s a m p l e of that w i d e r network. Nonetheless, on average, 40% of s u p p o r t clique m e m b e r s w e r e close kin: the p r o p o r t i o n of kin in the s u p p o r t clique w a s higher than w o u l d be e x p e c t e d if they w e r e d r a w n at r a n d o m from an acquaintances n e t w o r k of a b o u t 150 for 2 4 / 3 3 m e n a n d 5 4 / 6 6 w o m e n (X2 = 6.82 a n d 26.73, respectively; df = 1, P < 0.01 in b o t h cases). As with total n e t w o r k size, b o t h m e n a n d w o m e n t e n d e d to select the t w o sexes of kin with a b o u t e q u a l f r e q u e n c y as s u p p o r t sources ( m e a n p e r c e n t a g e of kin s u p p o r t sources that w e r e male: 49.1% for m e n a n d 40.6% for w o m e n ) . H o w e v e r , a m o n g n o n - k i n sources of s u p p o r t , m e n and w o m e n s h o w e d striking preferences for their o w n sex ( m e a n percent of m a l e s a m o n g non-kin s u p p o r t sources: 26.6% for w o m e n a n d 82.5% for m e n , M a n n - W h i t n e y test, z = 32.74, P < 0.001).

DISCUSSION

We h a v e s h o w n that the n u m b e r of i n d i v i d u a l s contacted on a r e g u l a r basis (i.e., at least once a m o n t h ) c o n f o r m s closely to that o b t a i n e d f r o m estimates of the size of " s y m p a t h y g r o u p s . " In selecting the m e m b e r s of

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this group, both sexes contact kin disproportionately more often than they do non-kin; as a result, the num ber of kin available ultimately limits the n u mb er of non-kin that can be included in the network. Women contact kin more often than men do, while both sexes exhibit a strong tendency for contacts with their own sex to be more com m on than contacts with the opposite sex. The inner clique of individuals from w h o m support or advice might be sought tends to mirror these preferences rather closely. These results are generally in line with those reported by both Rands (1988) and Booth (1972) for North American populations. Booth (1972) noted that while there were no differences in network size between m en and women, there did seem to be a sex difference in social participation: men were more socially active than women, but w o m e n maintained stronger emotional ties with their contacts and had more ties with kin than men did. Our results suggest that the sizes of both networks and support cliques are bimodal. Although part of the difference between small and large networks can be attributed to the reproductive status of individuals, it seems that there is some residual variation in network size that is due to differences in sociability. Although network size is known to vary with life history stage (Larson and Bradney 1988), the possibility remains that some of the variance in network size is due to differences in personality. We are currently exploring this possibility in more detail. The preference for kin over non-kin seems to be in line with what would be expected from the theory of kin selection (that individuals will prefer to associate with a n d / o r be altruistic towards kin w hen all other things are equal). In a now classic study of a working class community in the east end of London during the 1950s, Young and Willmott (1957) found a similar tendency for male and female networks to be distinct and largely sex-specific. They also noted that kinship played a particularly important role in female networks, with mothers and daughters forming what amount to mutually supportive alliances. Bott (1971) also reported a tendency for maternal relatives to be more important than paternal relatives in the social lives of London middle-class families. The present study provides quantitative support for these largely informal studies; it also suggests that these effects have remained stable despite the enormous changes that have taken place in British society over the past half century. These results appear to be at odds with the view that h u m a n societies are typically patrilocal (e.g., Foley and Lee 1989; Levi-Strauss 1969; Rodseth et al. 1991), such that in some cases women's kinship bonds are weakened or even severed. One possible reason w h y female kinship bonds may become relatively more important in m o d e r n industrial societies is that groups of males are no longer able to monopolize resources

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or other sources of i n v e s t m e n t that w o m e n n e e d for successful reproduction. In societies w h e r e m a l e k i n - b a s e d alliances a l l o w m e n to m o n o p o l i z e such services, w o m e n m a y be forced to choose b e t w e e n these services a n d their o w n kinship ties. In the absence of m o n o p o l i z able services, w o m e n m a y find that their o w n k i n - b a s e d alliances are m o r e valuable a n d m e n m a y then be less inclined to continue servicing their o w n kinship networks. The finding that kin do not p l a y a m o r e p r o m i n e n t role in the s u p p o r t clique t h a n they do in the f r i e n d s h i p n e t w o r k was, h o w e v e r , unexpected. That t h e y do not m i g h t reflect the fact that, in m o d e r n industrial societies, i n d i v i d u a l s often live too far f r o m their i m m e d i a t e kin to be able to use t h e m for h e l p in times of i m m i n e n t crisis. Unfortunately, w e did not ask individuals w h e t h e r they lived n e a r their kin (our concern w a s s i m p l y w i t h w h e t h e r or not t h e y contacted them), so w e are u n a b l e to d e t e r m i n e w h e t h e r those w h o p r e f e r r e d friends as sources of h e l p d i d so because they lacked n e a r b y kin. A l t h o u g h the e t h n o g r a p h i c literature suggests that kin are still w i d e l y seen as a p r i m a r y source of u n s t i n t i n g s u p p o r t b e c a u s e "blood is thicker t h a n w a t e r " (see, for e x a m p l e , Bott 1971; D u n b a r et al. 1995; L a r s o n a n d B r a d n e y 1988), the m o b i l i t y typical of m o d e r n society m a y m a k e it difficult for i n d i v i d u a l s to be as i n t i m a t e with g e o g r a p h i c a l l y distant relatives as they are w i t h u n r e l a t e d friends w h o m they see regularly. Indeed, Bott (1971) n o t e d a t e n d e n c y for kinship ties to w e a k e n w h e n relatives m o v e d a w a y (especially w h e n t h e y w e r e perceived as d o i n g so in o r d e r to better t h e m s e l v e s socially). We thank Lilian Cameron, Barbara Forest, Jean Scott, Mary Spoors, and Lisa White for help with distributing the questionnaires and the anonymous referees for their helpful comments. Robin Dunbar, B.A., Ph.D., until recently a professor of biological anthropology at University College London, is professor of psychology at the University of Liverpool. His main research interests concern mating systems and the evolution of mammalian social systems. Matt Spoors, B.Sc., M.Sc., teaches at St Hugh's School, Grantham (England).

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Bert6, N. 1988 K'ekchi' Horticultural Labor Exchange: Productive and Reproductive Implications. In Human Reproductive Behaviour, L. Betzig, M. Borgerhoff Mulder, and P.Turke, eds. Pp. 83-96. Cambridge: Cambridge University Press. Bliezner, R. 1988 Individual Development and Intimate Relationships in Middle and Late Adulthood. In Families and Social Networks, R. M. Milardo, ed. Pp. 147-167. Newbury Park, California: Sage Publications. Booth, A. 1972 Sex and Social Participation. American Sociology Review 37:183-192. Bott, E. 1971 Family and Social Network, revised edition. London: Tavistock Publications. Brown, B. B. 1981 A Lifespan Approach to Friendship: Age-related Dimensions of an Ageless Relationship. In Research in the Interweave of Social Roles, Vol. 2: Friendship, H. Z. Lopata and D. R. Maines, eds. Pp. 23-50. Greenwich, Connecticut: J. A. I. Burt, R. S. 1982 Towards a Structural Theory of Action: Network Models of Social Structure, Perceptions and Action. New York: Academic Press. Buys, C. J., and K. L. Larsen 1979 Human Sympathy Groups. Psychology Reports 45:547-553. Coleman, J. S. 1964 Introduction to Mathematical Sociology. London: Collier-Macmillan. Dunbar, R. I. M. 1992 Time: A Hidden Constraint on the Behavioural Ecology of Baboons. Behavioural Ecology and Sociobiology 31:35-49. 1993 Coevolution of Neocortex Size, Group Size and Language in Humans. Behavioral and Brain Sciences 16:681-735. Dunbar, R. I. M., A. Clark, and N. L. Hurst 1995 Conflict and Cooperation among the Vikings: Contingent Behavioural Decisions. Ethology and Sociobiology, in press. Firth, R., ed. 1956 Two Studies of Kinship in London. London: Athlone Press. Fischer, C. S. 1982 To Dwell among Friends: Personal Networks in Town and City. Chicago: University of Chicago Press. Foley, R., and P. C. Lee 1989 Finite Social Space, Evolutionary Pathways and Reconstructing Hominid Behavior. Science 243:901-906. Foot, H. C., A. J. Chapman, and J. R. Smith 1980 Friendship and Social Relations in Children. New York: Wiley. Hames, R. B. 1979 Relatedness and Interaction among the Ye'kwana: a Preliminary Analysis. In Evolutionary Biology and Human Social Behavior, N. A. Chagnon and W. Irons, eds. Pp. 238-249. North Scituate, Massachusetts: Duxbury Press.

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Rodseth, L., R. W. Wrangham, A. M. Harrigan, and B. B. Smuts 1991 The Human Community as a Primate Society. Current Anthropology 32:221-255. Thorne, B. I986 Girls and Boys Together.. ~ But Mostly Apart: Gender Arrangements in Elementary Schools. In Relationships and Development, W. W. Hartup and Z. Rubin, eds. London: LEA Press. Young, M., and R Willmott 1957 Family and Kinship in East London. London: Routledge and Kegan Paul.

Social networks, support cliques, and kinship.

Data on the number of adults that an individual contacts at least once a month in a set of British populations yield estimates of network sizes that c...
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