The company, (Twitter) meanwhile, is trying to avoid the bureaucracy that plagues larger businesses. The topic is important to Mr. Williams, who says he started companies because he didn’t believe in aligning himself with institutions. Twitter’s executives talk about the “Dunbar number” — the maximum number of people, generally believed to be 150, with whom one person can have strong relationships. This effort, mind you, comes from a company with a business model that fosters a multitude of ever-growing — and largely glancing — interactions among Twitter’s users. “I’ve never seen a company so focused on avoiding the Dunbar number,” says Adam Bain, who recently joined Twitter from the News Corporation as head of global revenue. “You can tell Ev planned it out.” Each time employees log on to their computers, for instance, they see a photo of a colleague, with clues and a list of the person’s hobbies, and must identify the person. And notes from every meeting are posted for all employees to read. Speaking to a group of new hires at an orientation session last spring, Mr. Williams said Twitter had three goals: to change the world, to build a business and to have fun. “You can succeed by only building a business, and many companies do,” he said. “We won’t consider it success unless it’s all three.”

When will "Magic Numbers" become central to HR? If you wish to look into Dunbar's work here is a link that will take you there directly.

I find it bizarre now that much of the science of human groupings is known, that few business schools or HR department pay any attention. They still work in the realm of Alchemy.

So for all of you who wish that your schools would not have bullying, that your organization would be more functional, that your church would be better, that your twitter experience itself would be more satisfying, that as a entrepreneur you could see see the perils in store as you grow - here is Rob's Coles Notes.

As a reminder - Here are the Lego Blocks of the science of human groups. From these precise grouping you build the best performing organizations.

As with Lego, there is nothing random about how best to organize human beings. All well functioning organizations use these groups and they avoid the "Dip" - you will see the "Dip" below.

8 The Circle of Intimacy (The section): where you intuitively communicate as a great sports team will - 15 the dangerous nowhere group that you must either go back to 8 or rush to 34 from - 34 the ideal compound group (The platoon) - 89 the ideal large team - 144 The maximum unit where all can know each other to use trust rather than rules.

source Christopher Allen

This graph by Christopher Allen was drawn from work on Guild sizes in WOW. They are aggregations of the data. They offer us a observable tendency to group according to the theory. It also shows that Dreaded Dip at about 15 people that also represents one of the worst hurdles for growing a small business. Moving from the "family" to the organization.

Our Tribal ancestors used to live in tribal groups of about 30+. The breakdown would be 8 men, 8 women and 15- 16 younger one.

So where do these numbers come from - for 144 or 150, the Dunbar Number is not the only number. The Numbers are of course found in the Fibonacci sequence

and are not made up but represent how nature stacks humans best. So here is the curve with the key numbers:

Here is how this was first put into practice - not because the Romans had a good theory but because they found that these numbers worked best in practice. The Roman Legion of more than 5,000 men was made up of units of 8 and 80. It had a head office of 3!!!!!

Here is the core of Dunbar's work - It is rooted in our evolution, our brain and the key insight that - humans use Culture to evolve more than biology. We live in a modern age but are wired as Neolithic People. Our wiring has not caught up with our culture.

It is generally accepted that human cultural evolution has proceeded at a very much faster pace than our anatomical evolution during the past few millenia. Given that our brain size has its origins in the later stages of human evolution some 250,000 years ago (Martin 1983, Aiello & Dean 1990), we may assume that our current brain size reflects the kinds of groups then prevalent and not those now found among technologically advanced cultures. The closest we can get to this is to examine those modern humans whose way of life is thought to be most similar to that of our late Pleistocene ancestors. These are generally presumed to be the hunter-gatherers (Service 1962, Sahlins 1972)............

In addition, it turns out that most organised (i.e. professional) armies have a basic unit of about 150 men (Table 3). This was as true of the Roman Army (both before and after the reforms of 104BC) as of modern armies since the sixteenth century. In the Roman Army of the classical period (350-100 BC), the basic unit was the maniple (or "double-century") which normally consisted of 120-130 men; following the reforms instituted by Marius in 104BC, the army was re-organised into legions, each of which contained a number of semi-independent centuries of 100 men each (Haverfield 1955, Montross 1975). The smallest independent unit in modern armies (the company) invariably contains 100-200 men (normallly three or four rifle platoons of 30-40 men each, plus a headquarters unit, sometimes with an additional heavy weapons unit) (Table 3). Although its origins date back to the German mercenary Landsknechts groups of the sixteenth century, the modern company really derives from the military reforms of the Swedish king Gustavus Adolphus in the 1620s. Despite subsequent increases in size to accomodate new developments in weaponry and tactics, the company in all modern armies has remained within the 95% confident limits of the predicted size for human groups. The mean size of 179.6 for the twentieth century armies listed in Table 3 does not differ significantly from the 147.8 predicted by equation (1) (z=0.913, P=0.361 2-tailed).

So what is your organization based on? What is being taught at your business school? What is your HR function telling you?