In a recent podcast on sex differences, psychologist Roy Baumeister mentions that men and women feel lonely for different reasons. Men feel a greater desire to belong to large, broad groups, and they therefore feel less socially satisfied when community life starts to evaporate. Women are not as alienated because they prefer fewer but closer friends, and you don't need a rich, extensive community environment to meet those goals.
This is one example of the pattern where males are thought to prefer more social relationships that are shallower in depth, while females are thought to prefer fewer but deeper connections. Baumeister reviews some of this in a talk on sex differences in sociality.
I used to believe that too, but changed my mind when I took a longer-term view of community life. The current idea is that a person has a fixed amount of time, energy, emotion, etc. to invest in social relationships. They can spread that out broadly across a lot of individuals (the supposedly shallow male connections), or concentrate it into a few (the supposedly intimate female connections). Within a given day, that does seem true: females don't interact with as many other people, but they spend a lot more time, and invest more emotionally, per individual that they do interact with.
But this view only looks at how diffuse or concentrated our social investment is across individuals. We could just as well look at how diffuse or concentrated the investment is over time. Sure, on a typical day a guy has fairly shallow connections to the people in his network -- but then look at how intensely they get each other pumped up on the weekend, for seasonal celebrations, annual rituals, undergoing rites of passage in groups rather than as individuals, going off to war (literally or figuratively), and so on.
So, men also concentrate their social investment into really intense relationships, but they concentrate it into fewer time periods rather than into fewer individuals like women do. And women also have a shallow aspect to their relationships -- they are shallow across time, rarely involving a short intense burst of team-work or working each other up into a frenzy that bonds them together for weeks, months, or years afterward. Their bonding activities are lower in intensity, like discussing how their day went, giving each other complements, making each other look prettier, helping each other solve their mundane problems, and so on.
Are these just two equal-valued points on a trade-off? That is, perhaps you could concentrate your social investment into a few intense time periods (males) or into a few close daily friends (females), but over the long term you would feel equally socially connected?
I don't think so. The male pattern produces bonds that can last a lifetime -- if you're a guy, you can contact any of your old friends or team-mates at any later point, and assuming you didn't have a disastrous falling-out, you can pick up almost right where you left off, and still feel like you've got each other's back. Girls tend not to stay close with even their supposedly more intimate friends for more than a few years. They have a very high turnover rate for friendships, and over the long term wind up more burned-out than satisfied socially. You only see this if you zoom out to the year or decade, beyond the day or week.
So when two best friends from high school meet up again 20 years later, they don't immediately get right back on the same intense wavelength, like when they were gossip buddies as teenagers. Not that they hate each other (though that too is more likely than among males), just that their spirits have come unglued, and they interact with each other like they would any other acquaintance. The guys 20 years later are still patting each other on the back, bumping chests, giving their secret handshakes, and splitting their sides laughing about their wild times together. Although it wouldn't be exactly as intense as it used to be, they could still go out to a bar or some other old haunt and have fun with a group they still felt they belonged to.
This is probably why men control just about any society whose scale is above that of hunter-gatherers, where the sexes are about equally powerful. The idea that they could accomplish that by relying on shallow relationships seems counter-intuitive at best, even silly if you stop and think about it. There must be some other way in which our relationships are more intense, and it is that they are more concentrated with respect to time rather than individuals.
These sporadic rituals are more saturated with the feeling of collective effervescence, communitas, or whatever you want to call it, compared to the daily private conversations of two BFFs. No pair or group of girls ever came away from a conversation feeling like guys do after playing a team sport, performing in a band, returning from the battlefield, or even being part of the audience of these performances. And far from being passive spectators, the mob in a sports stadium, the crowd at a concert or dance club, and the cheerleaders of war work themselves up into almost as great of a frenzy as those performing.
The key point here is to take a longer time horizon when looking at how deep or shallow people's social relationships are. When you pick a random time at a random day and see guys sitting around on the couch barely talking to each other, communicating more through a repertoire of grunts, you might be fooled into thinking that they had "many but shallow" relationships. To see their greater sociality, you'd have to hang around long enough to see them march off to the football stadium once a month to contribute to and feel nourished by the total heartbeat of the crowd.