Would you believe that a woman’s best friend in her 20s is a man with whom she maintains a bond that lasts for over 15 years? Then later, when she turns 50, her best friend is now another woman, a woman much younger than herself? This scenario is the complete opposite of the pop culture-induced stereotypes about the young socialite and the insecure cougar; however, this friendship pattern is actually the average among modern women.

In the context of reproduction, these relationships actually make sense. Scientific American covered a study that analyzed 1.95 billion cell phone conversations and 489 million texts. The overwhelming data indicates that women may be the driving force behind modern society. Based on the phone habits of over 3 million people from an anonymous European country (to protect privacy), it appears as though women develop the most pivotal relationships that perpetuate the human lifecycle. Skeptical? Read on… and keep an open mind.

An interdisciplinary team headed by University of Oxford’s anthropologist Robin Dunbar, sifted through data collected from over 3 million cell phone users and identified patterns of averages. On average, people in their 20s and 30s communicate the most with people close to themselves in age— and of the opposite sex. The rapport maintained with partners of the opposite sex, significantly supersedes that of any other type of relationship, suggesting that these opposite sex-relationships are probably of a romantic nature. On average, women maintain communication with their male bffs for about 15 years, 8 years longer than men maintain communication with their significant other.

At 50, women will no longer have a strong romantic relationship, but opt instead to form strong bonds with other, much younger women. Dunbar and his team have identified this older woman/ younger woman bond as a mother/daughter type scenario, and really, what else could it be? The fact that women form lasting relationships with men during their reproductive prime, may govern that a stable support system is maintained during childrearing. And the fact that older women maintain strong ties with women of childbearing age, suggests that older women are creating support systems for the younger generation, encouraging reproduction to continue.

Men aren’t quite as specific as women in their own friendship patterns. Men tend to distribute communication evenly among male and female friends. Also, men take longer to establish romantic relationships, peaking at 32 on average, compared to women, at 27. By women prioritizing a romantic relationship early on, they may be encouraging men to breed earlier. By establishing friendships with younger women later in life, women reiterate the importance of reproduction in society.

Scientists that believe this study demonstrates a matrilineal society may be on to something here. Other studies involving social media have shown that women prioritize Facebook friends with attractive people, thus cementing the idea that women are biologically driven.