You have 600 Facebook friends. How many will show up at your birthday party?

At a time when Facebook friend lists run several hundred - if not several thousand - names long, it can be easy to feel as if we live in a world with enormous emotional cocoons. But the truth is that while we share travel photos and life musings with a long list of virtual friends, the average person still only relies on a few people.

A new study by researchers at Chapman University surveyed more than 25,000 people to learn, among other things, the number of friends people of different ages, genders and sexual orientations feel close enough to to expect a certain level of emotional support from. The researchers probed participants about three separate measures of intimacy - the number of friends they expected to celebrate their birthday with, the number of friends they felt they could call to discuss their sex life with, and the number of friends they felt they could call or text at an unusual hour if they were in trouble.

What they found is that people tend to expect somewhere between five and 10 people to celebrate their birthday. The number of friends the average person feels comfortable discussing private matters (like their sex life) with and calling late at night, meanwhile, is even fewer - somewhere between four and seven people.

There is a bit of variance depending on age. Twenty-something-year-olds, for instance, tend to only expect somewhere between eight and 10 people to celebrate their birthday with them, while those 30 and older celebrate with somewhere between five and seven friends. Gender and sexual orientation seem to have a marginal effect as well. Gay and bisexual men, as well as bisexual women are much likelier to expect a similar number of close male and female friends to attend their birthday party, while others tend to count more heavily on those of the same gender.

A similar trend emerges for both discussions about one's sex life and unexpected late calls in the wee hours of the night.

Part of what is significant about their findings is that they seem to suggest a subtle but important step toward both gender equality and social acceptance of gays, lesbians, and bisexuals.

"Our findings suggest that sexual orientation differences in number of same-gender and cross-gender friends are generally small or nonexistent, and satisfaction with friends was equally important to overall life satisfaction for all groups," the researchers note. "The greater reliance on friends among gay men, lesbians and bisexual men and women has been true of past cohorts due to historical contexts and more prevalent homophobia."

But it also points to something else. As social as we social beings might be - especially in an age in which we are inundated with platforms that create illusory networks of close friends - we still only lean on a small circle of people for emotional support.