Social network size in humans

Human Nature (Impact Factor: 1.96). 04/2003; 14(1):53-72. DOI: 10.1007/s12110-003-1016-y

ABSTRACT This paper examines social network size in contemporary Western society based on the exchange of Christmas cards. Maximum
network size averaged 153.5 individuals, with a mean network size of 124.9 for those individuals explicitly contacted; these
values are remarkably close to the group size of 150 predicted for humans on the basis of the size of their neocortex. Age,
household type, and the relationship to the individual influence network structure, although the proportion of kin remained
relatively constant at around 21%. Frequency of contact between network members was primarily determined by two classes of
variable: passive factors (distance, work colleague, overseas) and active factors (emotional closeness, genetic relatedness).
Controlling for the influence of passive factors on contact rates allowed the hierarchical structure of human social groups
to be delimited. These findings suggest that there may be cognitive constraints on network size.

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