I am interested in opinions and/or studies that may lead to an accurate approximation of the size of terrorist groups around the world. I know opinions may vary widely. I have written several papers on the topic of Insurgents vs Terrorists, and have my opinion too. But I am interested in learning more. I came across a concept known as Dunbar's Number in which he makes an argument to the upper limits of social organizations. His research does not speak at all to terrorist groups--in fact his research was done many years before Oklahoma City, 911, or other attacks.

Dunbar has theorized that 150 would be the group size only for communities with a very high incentive to remain together. For a group of this size to remain cohesive, Dunbar speculated that as much as 42% of the group's time would have to be devoted to social grooming. Correspondingly, only groups under intense survival pressure, such as subsistence villages, nomadic tribes, and historical military groupings have, on average, achieved the 150-member mark. Moreover, Dunbar noted that such groups are almost always physically close: "... we might expect the upper limit on group size to depend on the degree of social dispersal. In dispersed societies, individuals will meet less often and will thus be less familiar with each, so group sizes should be smaller in consequence." Thus, the 150-member group would only occur because of absolute necessity, i.e. due to intense survival, security, environmental and/or economic pressures.

However, as with many theoretical values, it has occasionally been abused and mistaken as a "magic number". It has also been popularized as the monkeysphere, a neologism coined by David Wong in an article which introduces this concept.

In its popularization, the research of Dunbar and others is taken as an upper bound of the number of fellow humans that an individual can view as being "truly human". In this form, the "monkeysphere" functions as a reductionistic and biologistic explanation for why humans can treat some humans with consideration and other humans indifferently or even inhumanely.

"The reason that the people in village X don't mind doing Y to the people in village Z is because the people in village Z are not in the monkeysphere of people in village X."

Recently, I took the liberty to study our Small Wars Community and found that if you add up the number of members on our site and then subtract those that had zero or only one response ever to the postings, the numer falls within the range of Dunbar's postulate.

For the sake of this thread, I ask that we separate Insurgencies from Terrorist operatives. In addition, I ask that we define terrorists members as "Card Carrying." In other words, it is OK to be dienfranchised but I would define a card carrying member as one who has a call to arms and will act upon that calling.