Friend requests, followers, and notifications may make you out to be a social butterfly. However, despite how many friends you have, the truth is you’re only friends with less than half of your followers. In Brain Craft’s new video, “How many friends can you have?” writer and host Vanessa Hill says the magic number depends on the size of this part of the brain.

It is through the social brain hypothesis we are able to understand the size of our neocortex. It is believed its size is correlated with the size of our social groups. This is the outer layer of the brain that’s responsible for our higher functions, like conscious thought, language, or spatial reasoning.

A study published in the Journal of Human Evolution looked at the neocortex of other primates and compared it as a ratio to the size of the rest of their brain. Lemurs with a smaller live in social groups of nine compared to long-nosed monkeys with a larger neocortex who live with a group of 14. Meanwhile, the western red colobus monkeys with a slightly larger neocortex lived in groups of 32, but the chimpanzee — with the largest neocortex of all primates, except for humans — lives in groups of 53.

This pattern could be applied to humans except we don’t all live in local groups because we don’t groom each other like other primates. This led to the Christmas card experiment in a study published in the journal Human Nature. Researchers found the sending of Christmas cards can serve as a reflection of our social network. The average number of cards sent was 68, while a person’s average social network size was 153. This number reflects British anthropologist Robin Dunbar’s number that suggests our cognitive limit only allows us to comfortably maintain 150 stable relationships.

Dunbar’s number is consistent with the group size and Neolithic farming villages and armies during the Roman times. He also believes since our neocortex can only be so big, it’s actually harder for our brain to accommodate more relationships despite of what our social networks say.

Recent studies have built on this theory and suggest other brain regions may be able to determine more about our social life. The orbital prefrontal cortex, located just above the eyes, can actually determine whether you’re good at keeping friends, according to a 2012 study published in the journal Proceedings of the Royal Society B: Biological Sciences. "We found that individuals who had more friends did better on metalizing tasks and had more neural volume in the orbital frontal cortex, the part of the forebrain immediately above the eyes," said study author R.I.M. Dunbar. "The frontal lobes of the brain, in particular, have enlarged dramatically in humans over the last half million years."

Face-to-face interactions are what Dunbar considers a good quality relationship. The physical proximity to our friends and loved ones means we release more endorphins and have a higher level of oxytocin, which is needed for social bonding. As brain regions continue to evolve over time, it is possible we may be able to accommodate more friends than just 150.