Paper Towns and Dope are two examples of new youth-oriented and well-reviewed films that focus on a small group of close friends—the number just happens to be three in each. One of the messages of Paper Towns, furthermore, is that the lead female character, a romantic interest for one of the three male friends, is someone who “by trying to be friends with everyone, she isn’t truly friends with anyone” (Huffington Post).

Which leads me to ask: In this era of massive social media “friending” (for some), how many friends do most of us actually have, and how many do we need?

As reported by Markham Heid, Time, the research of evolutionary psychologist Dr. Robin Dunbar finds that optimally we need three to five of the bestie, in-your-real-life variety. And of the invite-to-a-large-party variety, maybe 100-200 folks, tops.

Maybe you’ve already heard of this as “Dunbar’s number” (often quoted as “150”), indicating that our brains may actually be unable to handle more than that—and not indicating, on the other hand, that we actually need this many people in our lives.

What about social media connections? According to Sophia Dembling, Psychology Today, “Research reveals that the ideal number of Facebook ‘friends’ is 302. That’s enough so you don’t seem pathetic, not so many that you seem needy.”

An excess of this type of friend, however, isn’t good for your stress level, says clinical social worker Amy Morin (Psychology Today), as there’s “increased anxiety about offending people. This effect stemmed from people’s desire to present a version of themselves that would be acceptable to all their social media contacts. While your college buddies may enjoy publicly discussing that weekend in Vegas, your parents and co-workers may be less than impressed.”

No matter what type, it’s okay to have only those friends that make a positive enough difference—and that number is likely to be on the smaller side. When it comes to close friends, then, quality versus quantity.

Notably, Dunbar adds that your closest 15 family and friends are the “most crucial when it comes to your mental and physical health.” Which raises yet another question: Who matters more—friends or family? More from Dunbar:

…(T)hat’s not to say a brother or sister offers you the same benefits as a close friend…While your kin are more likely to be there for you when you need help, your good friends tend to fire up your nervous system and trigger the release of feel-good neuropeptides called endorphins. Whether you’re laughing with your pal or feeling him or her touch your shoulder in sympathy, the resulting rush of endorphins seems to ‘tune’ up your immune system, protecting you from disease, Dunbar explains.

Other pertinent research in recent years includes the following results:

• Although Americans used to average three confidants, we’re now down to two (NBC)…
• Whereas research across the pond reveals that young adult females in Britain average five true friends. “True friends were classed as those you’d turn to in an emergency, friends you can talk to about anything and those that support and love you regardless of the situation.” (Daily Mail)
• “Despite the flurry of posts and photos on Facebook and Twitter…people maintain the same number of close friends throughout their entire lives. Each of us has what researchers call a unique ‘social signature,’ which we tend to keep throughout our lives by dropping old friends when new ones arrive, making the size of our inner circles mostly constant.” (New York Daily News)
• To put it another way, “…(H)umans have, almost uniformly, a ‘one-in-one-out’ policy—every time you become close to a new person, someone else subconsciously gets the boot.” (Motherboard)

No wonder, then, that some of our old friends, no matter how close, feel threatened when new ones come along.