  Homophily describes a fundamental tie-formation mechanism in social networks
in which connections between similar nodes occur at a higher rate than among
dissimilar ones. In this article, we present an extension of the Weighted
Social Network (WSN) model that, under an explicit homophily principle,
quantifies the emergence of attribute-dependent properties of a social system.
To test our model, we make use of empirical association data of a group of
free-ranging spider monkeys in Yucatan, Mexico. Our homophilic WSN model
reproduces many of the properties of the empirical association network with
statistical significance, specifically, the average weight of sex-dependent
interactions (female-female, female-male, male-male), the weight distribution
function, as well as many weighted macro properties (node strength, weighted
clustering, and weighted number of modules), even for different age group
combinations (adults, subadults, and juveniles). Furthermore, by performing
simulations with fitted parameters, we show that one of the main features of a
spider monkey social system, namely, stronger male-male interactions over
female-female or female-male ones, can be accounted for by an asymmetry in the
node-type composition of a bipartisan network, independently of group size. The
reinforcement of connections among members of minority groups could be a
general structuring mechanism in homophilic social networks.
