Mothers tend to make calls more to their daughters than to their sons, fathers to their sons than to their daughters; for younger callers, most of their calls go to the same generation contacts, older people call the younger more frequently

Quantifying gender preferences in human social interactions using a large cellphone dataset. Asim Ghosh et al. EPJ Data Science, December 2019, 8:9 (online Mar 2019). https://link.springer.com/article/10.1140/epjds/s13688-019-0185-9

Abstract: In human relations individuals’ gender and age play a key role in the structures and dynamics of their social arrangements. In order to analyze the gender preferences of individuals in interaction with others at different stages of their lives we study a large mobile phone dataset. To do this we consider four fundamental gender-related caller and callee combinations of human interactions, namely male to male, male to female, female to male, and female to female, which together with age, kinship, and different levels of friendship give rise to a wide scope of human sociality. Here we analyse the relative strength of these four types of interaction using call detail records. Our analysis suggests strong age dependence for an individual of one gender choosing to call an individual of either gender. We observe a strong bonding with the opposite gender across most of their reproductive age. However, older women show a strong tendency to connect to another female that is one generation younger in a way that is suggestive of the grandmothering effect. We also find that the relative strength among the four possible interactions depends on phone call duration. For calls of medium and long duration, opposite gender interactions are significantly more probable than same gender interactions during the reproductive years, suggesting potential emotional exchange between spouses. By measuring the fraction of calls to other generations we find that mothers tend to make calls more to their daughters than to their sons, whereas fathers make calls more to their sons than to their daughters. For younger callers, most of their calls go to the same generation contacts, while older people call the younger people more frequently, which supports the suggestion that affection flows downward. Our study primarily rests on resolving the nature of interactions by examining the durations of calls. In addition, we analyse the intensity of the observed effects using a score based on a null model.

Keywords: Social networks Egocentric networks Mobile phones Life history Gender differences Sex differences

FF    female caller–female callee
FM    female caller–male callee
MF    male caller–female callee
MM    male caller–male callee

1 Introduction

In social interactions between humans, gender and age play a key role in the communities and social structures they form and the dynamics therein. For the caller–callee interactions in mobile communication there are four fundamental possibilities, namely male to male, male to female, female to male, and female to female, which together with age, kinship, and different levels of friendships affect the strengths of social interactions, giving rise to a wide scope of human sociality. The studies of primate brain size and its relation to their average social group size suggest that humans are able to maintain of the order of 150 stable relationships (Dunbar number) [1, 2, 3]. In addition the Social Brain hypothesis suggests that on the basis of emotional closeness human social networks can be divided into four cumulative layers of 5, 15, 50 and 150 individuals, respectively [4]. The concept of emotional closeness is, in general, hard to quantify, but previous studies have shown how it can be associated with the frequency of communication between two individuals [5, 6]. This makes the concept quantifiable such that one can observe how much an individual shares social resources with his or her contacts of different gender and age.

Over the past decade or so, much research on human communication patterns has been done by using “digital footprints” data from modern communication technologies such as mobile phone calls and text messages as well as social media like Facebook, and Twitter [7, 8, 9]. Of these the mobile phone communication data of call detail records (CDRs) has turned out to help us in getting insight into the structure and dynamics of social networks, human mobility and behavioural patterns in much finer details than before [7]. It has also revealed how microscopic properties related to individuals translate to macroscopic features of their social organization such as networks. As a result of these studies we now have quite a good understanding of a number of structural properties of human social networks such as degree, strength, clustering coefficient, community structure, and motifs [10, 11, 12].

Apart from these basic structural properties of networks, more recent studies have given us insight into a number of other aspects of social networks, namely their dependence on temporal, geographic, demographic, and behavioral factors of individuals in the network [13, 14, 15, 16, 17]. One such observation pertains to the shifting patterns of human communication across the reproductive period of their lives, which appears to reflect parental care [18, 19]. Another is a study using the postal code information in the data to show that the tie strength is related to geographical distance [20]. In addition, it has been shown that there is a universal pattern of time allocation to differently ranked social contacts [21]. Finally, recent studies indicate variation in connections and the number of friends with the age and gender [22, 23]. The importance of the strength and significance of communication with top-ranked contacts have also been studied in detail [18, 22].

In the present study, we focus on measuring the relative strengths of the four possible pairwise caller–callee interactions over their lifespans as a function of the caller’s age. From the point of view of call initiation, we find that females play a more active role during their reproductive years as well as during their grandmothering period [24, 25]. The grandmothering hypothesis is usually studied in the context of human longevity and evolutionary benefits. The notion deals with the focus of post-menopausal on their grandchildren. In general, the social focus of women are known to shift from the opposite gender in the same age cohort, when they are young, to the age cohort of their children, as they grow older. We observe that while females of grandmothering age are found to give more attention to their children, males up to the age of 50 years still keep stronger connection with their spouses of slightly younger age. Furthermore, the fraction of calls to individuals of different generations indicates that mothers tend to call their daughters more than their sons, whereas fathers call their sons more than their daughters. For younger individuals, most of their calls go to contacts of the same generation, whereas older people call younger people more frequently. The calling activity of older adults with the younger individuals who are below or around their reproductive age would signify parental and alloparental care, that is, caring for the children of children. We group these kind of behaviour as affection flows downward.