'''Dunbar's number''' is a suggested cognitive limit to the number of people with whom one can maintain stable social relationships—relationships in which an [[individual]] knows who each person is and how each person relates to every other person.<ref name="dunbar92"/><ref>{{cite book |last=Gladwell |first=Malcolm |title=The Tipping Point – How Little Things Make a Big Difference |url=https://archive.org/details/tippingpointhowl00glad |url-access=registration |year= 2000 |publisher=Little, Brown and Company |isbn=978-0-316-34662-7 |pages=[https://archive.org/details/tippingpointhowl00glad/page/177 177]–181, 185–186}}</ref> This number was first proposed in the 1990s by British [[Anthropology|anthropologist]] [[Robin Dunbar]], who found a correlation between primate brain size and average social group size.<ref name="facebook study"/> By using the average human brain size and extrapolating from the results of primates, he proposed that humans can comfortably maintain 150 stable relationships.<ref>{{cite book|title=Principles of Cognitive Neuroscience|first=Dale|last=Purves|publisher=Sinauer Associates|location=Sunderland, Mass.|isbn=9780878936946|date=2008}}</ref> Dunbar explained it informally as "the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar".<ref>{{cite book|url=https://archive.org/details/isbn_9780674363366|url-access=registration|title=Grooming, gossip, and the evolution of language|date=1998|publisher=Harvard University Press|isbn=978-0674363366|edition=1st Harvard University Press paperback|location=Cambridge, Massachusetts|page=[https://archive.org/details/isbn_9780674363366/page/77 77]|quote=|via=|last1=Dunbar|first1=Robin|accessdate=17 December 2016}}</ref> | '''Dunbar's number''' is a suggested cognitive limit to the number of people with whom one can maintain stable social relationships—relationships in which an [[individual]] knows who each person is and how each person relates to every other person.<ref name="dunbar92"/><ref>{{cite book |last=Gladwell |first=Malcolm |title=The Tipping Point – How Little Things Make a Big Difference |url=https://archive.org/details/tippingpointhowl00glad |url-access=registration |year= 2000 |publisher=Little, Brown and Company |isbn=978-0-316-34662-7 |pages=[https://archive.org/details/tippingpointhowl00glad/page/177 177]–181, 185–186}}</ref> This number was first proposed in the 1990s by British [[Anthropology|anthropologist]] [[Robin Dunbar]], who found a correlation between primate brain size and average social group size.<ref name="facebook study"/> By using the average human brain size and extrapolating from the results of primates, he proposed that humans can comfortably maintain 150 stable relationships.<ref>{{cite book|title=Principles of Cognitive Neuroscience|first=Dale|last=Purves|publisher=Sinauer Associates|location=Sunderland, Mass.|isbn=9780878936946|date=2008}}</ref> Dunbar explained it informally as "the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar".<ref>{{cite book|url=https://archive.org/details/isbn_9780674363366|url-access=registration|title=Grooming, gossip, and the evolution of language|date=1998|publisher=Harvard University Press|isbn=978-0674363366|edition=1st Harvard University Press paperback|location=Cambridge, Massachusetts|page=[https://archive.org/details/isbn_9780674363366/page/77 77]|quote=|via=|last1=Dunbar|first1=Robin|accessdate=17 December 2016}}</ref> |