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100 Things You Should Know About People: #30 — Our "strong tie" group size is 150 people



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Evolutionary anthropologists study social groups in animals. One question they have been trying to answer, is whether there is a limit on how many individuals different species have in their social group. Robin Dunbar studied the relationship between brain (neo-cortex) size and the number of stable relationships that a species had in their social groups. Based on his findings with animals, he extrapolated to what the number would be for humans. Called “Dunbar’s Number”, he postulated that 150 people is the social group size limit for humans. (To be more exact, he calculated the number at 148, but rounded up to 150. Also there is a fairly large error measure, so that the 95% confidence interval is from 100 to 230 – for you statistical experts out there).

A limit to stable, social relationships — The limit specifically refers to the number of people that you can maintain stable social relationships with. These are relationships where you know who the person is, and you know how each person relates to every other person in the group. Dunbar has documented the size of communities throughout different geographic areas and throughout different historical timeframes, and he is convinced that this number holds true.

Across time and cultures — Dunbar assumes that the current size of the human neocortex showed up about 250,000 years ago. So he started his research with hunter-gatherer communities.  His observations include: Neolithic farming villages averaged 150 people, as did Hutterite settlements, professional armies from the Roman days as well as modern army units.

Intense survival pressure — His claim is that 150 is the group size for communities that have a high incentive to stay together. If the group has intense survival pressure, then it stays at the 150 member mark. He also notes that these groups are usually in close physical proximity. If the survival pressure is not intense, or the group is physically dispersed, then he estimates the number would be lower.

Too high or too low? — Some critics of Dunbar’s number say that the number is too high, and others that it is too low. In the world of social media people have 750 facebook friends or 4,000 twitter followers, showing that the number of 150 is way off the mark. A Dunbar fan would respond that these are not the strong stable relationships where everyone knows everyone and people are in physical proximity. Some critics say the number of 150 is too high – that the number of people one is close to both physically and socially is much less than 150.

It’s the weak ties that are important?– In a blog post Jacob Morgan says that what’s really important in social media is not the strong ties that Dunbar talks about, but the weak ties – relationships that do not require that everyone knows everyone in the group, and that are not based on physical proximity. He argues that the reason that social media is so interesting is that it allows us to quickly and easily expand these “weak” ties, and that those are the ties that are most relevant in our modern world.

Substituting weak for strong — I think both Dunbar and Morgan are right. It’s critical that we pay attention to that 150 number for our “survival” community in close proximity. If we don’t feel we have that “tribe” near us it causes us to feel alienated, isolated and stressed. Perhaps one of the reasons social media is so popular, and so many of us rely on Facebook and Twitter is that we don’t have a strong tie tribe. Although the weak tie network of social media helps us to feel connected, we’ll eventually feel let down if we try to have it substitute for a strong tie Dunbar tribe.

For more information, I suggest you watch this interview of Robin Dunbar:

And read Jacob Morgan’s blog post:

What do you think? Do you have a strong tie tribe network? Are you ultimately trying to substitute with your weak tie network? In our modern world is the weak tie network more important?


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One response to “100 Things You Should Know About People: #30 — Our "strong tie" group size is 150 people”

  1. Mathdelane Avatar

    I came across this site via your WebproNews’ interview. Good job on that! I do find this topic really interesting. Close tie tribe on my end are mostly people that I used to work with or have met before and generally close to a hundred percent know these people entirely that’s why I keep my Friendster (a social networking site more famous in Asia) account exclusive only to those people I know. In fact, having less than a hundred can sometimes become overwhelming so what more if there are thousands. Human interactions don’t always happen even on strong ties thus these stronger ties can grew weaker if not maintained which means that the 150 Dunbar number could fluctuate overtime.

    Weak ties however can be significant and maybe because of Twitter’s over-hyped popularity, users find it ego-boosting in some sense to find yourself with overwhelming number of followers when in reality at the end of the day, only a few or even a handful of them respond to your tweets or even click on your shared links because the site had so much information overload and interaction is becoming more of a struggle than a healthy experience.

    In think in the long haul, stronger ties more likely defines what social networking is all about and that’s also why there’s a term called social circle–an endless interactive relationship where everyone is connected and is a part of a whole.
    .-= Mathdelane ´s last blog ..Virus Alert: Facebook Password Reset Confirmation Support Message Attachments =-.

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