How Large Is Your Network? What Does Dunbar’s Number Really Mean?

Dunbar’s Number is one of the most misunderstood concepts in sociology. We address it somewhat quickly in The Start-Up of You. In Reid’s latest LinkedIn post, we explain the nuance behind limits to the number of people in your network:

Imagine you receive a digital camera with a built-in memory card for your birthday. You bring it on a six-month trip to Africa where you won’t have access to a computer—so all the photos you want to keep must fit on that one memory card. When you first arrive you snap photos freely, and maybe even record some short videos. But after a month or so, the memory card starts filling up. Now you’re forced to be more judicious in deciding how to use that storage. You might take fewer pictures. You might decide to reduce the quality/resolution of the photos you do take in order to fit more. You’ll probably cut back on videos. Still, inevitably, you’ll hit capacity, at which point if you wish to take new photos you’ll have to delete old ones.

Just as a digital camera cannot store an infinite number of photos and videos, you cannot maintain an infinite number of relationships. Which is why, even if you are judicious about your choices, at some point you hit a limit, and any new relationship means sacrificing an old one.

The maximum number of relationships we can realistically manage—the number that can fit on the memory card, as it were—is described as Dunbar’s Number, after evolutionary psychologist Robin Dunbar. But maybe it shouldn’t be. In the early nineties, Dunbar studied the social connections within groups of monkeys and apes. He theorized that the maximum size of their overall social group was limited by the small size of their neocortex. It requires brainpower to socialize with other animals, so it follows that the smaller the primate’s brain, the less efficient it is at socializing, and the fewer other primates it can befriend. He then extrapolated that humans have an especially large neocortex and so should be able to more efficiently socialize with a great number of humans. Based on our neocortex size, Dunbar calculated that humans should be able to maintain relationships with no more than roughly 150 people at a time. To cross-check the theory, he studied anthropological field reports and other clues from villages and tribes in the hunter-gatherer era. Sure enough, he found the size of surviving tribes tended to be about 150. And when he observed modern human societies, he found that many businesses and military groups organize their people into cliques of about 150. To wit: Dunbar’s Number of 150.

But Dunbar’s research is not exactly about the total number of people that any one person can know. The research focused on how many nonhuman primates (and humans, but only by extrapolation) can survive together in a tribe. Of course, group limits and the number of people you can know are closely related concepts, especially if you consider everyone in your life to be part of your social group. Yet most of us define our total social group more broadly than Dunbar did in his research. Survival in the modern world doesn’t depend on having direct, face-to-face contact with everyone in our social network/group, as it did for the tribes he studied.

Regardless of how you parse Dunbar’s research, what is definitely the case is that there is a limit to the number of relationships you can maintain, if for no other reason than the fact that we have only twenty-four hours in each day. But, contrary to popular understanding of Dunbar’s Number, there is not one blunt limit. There are different limits for each type of relationship. Think back to the digital camera. You can either take low-resolution photographs and store one hundred photos in total, or you can take high-resolution photographs and store forty. With relationships, while you can only have a few close buddies you see every day, you can stay in touch with many distant friends if you only email them once or twice a year.

But there’s a twist. While the number of close allies and weak ties you can keep up is limited, those aren’t your only connections. You can actually maintain a much broader social network that exceeds the size of the memory card. It’s by smartly leveraging this extended network that you fully experience the power of I-to-the-We.

Your extended network are your 2nd and 3rd degree connections. Read the whole post for more.

Lessons and Reflections from Publishing the Start-Up of You

I just published a long article/essay on the process of publishing The Start-Up of You. In addition to sharing background on how Reid and I came to partner on the book, I share lessons learned and insights on the key editorial questions that define a book, how to ask for and incorporate feedback from early readers, the reality of self-doubt and self-dissapointment that’s part of the process in a project like this, and much more. I hope it’s useful for authors and entrepreneurs alike. Since it’s long, I suggest printing or viewing in Readability mode for your convenience. Enjoy!

Start-Up of You Student Fellowship

We’re pleased to announce the Start-Up of You Student Fellowship for current college students. Reid and I want to recognize current college students who are especially entrepreneurial in their life and career — and empower them to do even more. Fellows will be part of an exclusive network during the fall 2012 semester. If you’re a student or know someone who is, learn more about the fellowship here and about our general student outreach here. Hurry – application deadline is July 31!


Odds and ends:

  • Over 500 of you shared your ideas for how you want to take on risk in your career in our post on the Four Hour Workweek blog. We picked the best three stories (from so many inspiring ones!) and now it’s time to vote on who should win the mentorship prize.
  • A great 25 minute video profile from Bloomberg Game Changers on Reid, featuring commentary from Eric Schmidt, Dave Goldberg, Mark Pincus, and Jeff Weiner.

How to Take Intelligent Risk and Become Resilient to Anything

Reid and I wrote a long post on how to take intelligent risk in your career and become resilient to anything. It contains some of my favorite material from one of the key chapters of The Start-Up of You. Leave a comment over on the 4HWW post, introduce yourself, and tell us:

– What change do you want to make in your career in the next 30-60 days? (e.g. Change jobs, ask for a raise, find a new opportunity within your company)
– How are you thinking about the risk involved in this move?

We’ll select the person who leaves the most thoughtful comment no later than 5pm PST, June 21 (Thursday), and personally invest in making that person’s next career move successful.

Here’s what we can offer:

– Over email and in a 30-minute phone call, we’ll suggest relevant opportunities, key people to meet, and provide motivational support. The initial 30-minute call will be with me (Ben), and the follow-up emails will include Reid.
– Two signed copies of The Start-Up of You.
– Your story will be highlighted in our LinkedIn Group.
– Free Linkedin Premium subscription


New to this blog? Here are some popular posts over the years.

Are You Network Literate?

It was fun being back on public radio’s Marketplace this week, with a commentary on network literacy.

Here’s the opening:

Bill Gates once wrote that “The most meaningful way to… put distance between you and the crowd is to do an outstanding job with information. How you gather, manage, and use information,” Gates wrote, “will determine whether you win or lose.”

What’s hard is that the information modern professionals need is always changing. Simply stockpiling facts and knowledge won’t get you anywhere. Rather, you need to know how to access the information you need, when you need it.

You can listen to the audio on the page or embedded below.

Start-Up of You: Odds and Ends

A few odds and ends:

— We were pleased to see a favorable review of the book in The Economist. Check it out:

“IF YOU start me up. If you start me up I’ll never stop”. Mick Jagger and Keith Richards probably did not have career advice in mind when they wrote these lyrics. But thinking like a start-up seems to be an excellent way for workers to prosper in a world in which the notion of a job for life has been consigned to the scrapheap. By being on the lookout for new opportunities all the time, changing course if markets shift and tapping professional contacts for advice and leads, people can avoid ending up on the slush pile themselves.

— A particularly rewarding outcome of the project for us has been the thousands of people who have shared their stories about what they now do differently in their career. We’ve featured some of the Reader Stories on the book site. Read the stories and get inspired to enact change in your own career…

— I’ll be speaking in Milan next week (and elsewhere in Italy) and Toronto the week after. You can buy a ticket to the Toronto gig here; email me for info on Italy.

— The Start-Up of You LinkedIn Group has been vibrant, and there are several interesting threads. You can join the community for free. Here are a few recent threads:

— The trailer for the book has over 710,000 views. Reid also recorded about a dozen short video clips about investing in yourself that you can watch as a playlist at YouTube.

Sentence of the Day

The most highlighted sentence from the Kindle version of The Start-Up of You is:

The fastest way to change yourself is to hang out with people who are already the way you want to be.

I did have a feeling that sentence was a winner when we wrote the book, but in the electronic age it’s interesting to be able to see data around it.

I should note that there is a rich-get-richer effect with highlights on the Kindle. Unless you turn it off, as a reader you begin to automatically see flags on the sentences that other readers have most underlined. This no doubt influences you to highlight the same.

Steve Jobs Focused on Network Intelligence

I read Adam Lashinky’s new book Inside Apple: How America’s Most Admired–And Secretive–Company Really Works on my flight to Doha, and I picked up a bunch of nuggets. Here’s one section that jumped out:

An unsung attribute of Steve Jobs that Apple also will miss is his role as a masterful networker and gatherer of information…He furiously worked the phones, calling up people he’d heard were worthy and requesting a meeting. No one turned down the chance to meet with Jobs, of course, and he used the opportunity to soak up information. His uncanny insight into trends in business and technology weren’t a fluke. Jobs worked hard for his market intelligence.

It follows with a story of Jobs hearing that Lytro was a cool company, calling the company’s CEO and inviting the Lytro CEO over to his house to discuss cameras and product design. According to the Forbes cover piece on Dropbox, Jobs did something similar with the founders of Dropbox. And surely countless other entrepreneurs.

Some of these conversations are of course driven with M&A in mind, but I follow Lashinsky’s point that much of this is Jobs’s instinct to always be pulling intelligence from his network about what’s happening in the world in order to be a more effective and informed professional.

Jobs took advantage of the density of Silicon Valley. He could summon the best young entrepreneurs, like Drew Houston, to his office on a day’s notice. He went on walks with Mark Zuckerberg. This is probably one reason he evangelized the region so much–increased density equals increased network intelligence for those living in the density.

Jobs was tapping networks inside Silicon Valley but outside of Apple corporate–and this was crucial. Lashinsky writes, “The rest of the crew at Apple is either too busy to schmooze or was always discouraged by Jobs from doing it, lest they get too big for their britches or too distracted from their Apple work.” Jobs once said he didn’t want to let exec Scott Forstall “out of the office” — which is great if someone needs to just put their head down and execute, but tunnel vision is not super helpful for fresh ideation.

Lashinksy asks who at Apple will be gathering this outside-the-company network intel with Jobs gone. It’s a good question. Meanwhile, we can all be asking ourselves a similar question in our careers: How are we pulling network intelligence from diverse sources in order to be better at the job we already have or to find a new opportunity? That’s a key theme of The Start-up of You.

Free Webcast Thursday Night

This Thursday March 29th at 6:30 PM pacific time — join Reid Hoffman and me for a live, free webcast to discuss the Start-Up of You and hear us answer your questions related to careers and the future of work. You should join the webcast if you’ve read the book or are thinking about reading it.

There’s a limited number of spots, so be sure to click here and then click “Register” to claim your spot. (If you’ve already submitted contact info on a Wufoo form via another blog, no need to do anything more.)

Look forward to talking to you on Thursday evening.


At SXSW the other week, an artist drew an illustration of our presentation as we were talking. I’ve pasted it below. Click to enlarge. I’m amazed it was done in real time.

Build On Your *Underlying* Strengths When Adapting

Play to your strengths. It’s common advice, and it makes sense. People go farther by figuring out what naturally comes easy and organizing their activities accordingly, instead of working overtime to compensate for weaknesses. The problem is that when people think about making career moves they often interpret “strengths” in a narrow industry context.

For example, say you’ve spent a decade in finance. You’ve developed serious experience, expertise, and industry connections. If you’re trying to build on your strengths, the right next career move would be to leverage these abilities into some other job in finance.

Yet, you might not like finance. You may not be thriving. Perhaps your calling is elsewhere. But because you want to leverage the soft assets you’ve built up over time, you stick with it. This is how many people end up working the same industry for years on end. In part, they were “building on their strengths.”

In the book, we talk about why evaluating your existing assets–of which strengths are one part–cannot be done in isolation. You should think about them in the context of your aspirations, and in the context of what people will pay for. All these things change over time.

If your aspirations or values are shifting, and you want to pivot to Plan B, better to think about your underlying strengths and focus on the transferable qualities of your most recent experiences. Project management is project management. Relationship building is relationship building. Some expertise is context specific. But not all of it is. Zoom out and think about the more universal characteristics of what you’re good at. Then match that to the market realities.

We feature James Gaines in the book, who pivoted from head honcho at Time Magazine (where he interviewed dozens of heads of state) to running a digital media startup. He saw his strength as “telling good stories”–not being editor of a print magazine. Storytelling was the underlying strength that enabled the pivot out of print journalism.

Bottom Line: You can still build on your strengths even if you are adapting your career into new industries, geographies, networks.