The Reasons For Silos


Reason 1 - Magical 150 We can predict from human instincts that intra-organisational rivalries and turf protection will occur in organisations that employ more than 150 people.

The size of the human brain drives the size of group from which we gain our identity. Oxford professor Robin Dunbar is an expert on the topic. He argues that living in complex social groups demands a significant amount of intellect – to keep in touch with and manage the complexities of relationships with others in your community. Humans have the largest brain per body size of any animal on the planet. On Dunbar’s analysis the brain per body ratio of humans correlates to community size of 150, which is indeed the size of primitive, or natural, human groups.
The magical 150 appears in various places:
On Facebook, the average number of friends in a network is 120. If you take the time to list your friends and acquaintances you will list around 150 people.

The global CEO of Proctor & Gamble nominates 150 as the number of high potential people he personally monitors.

When Barbara Williams, the mother of Australian crime figure, Carl Williams died, 150 people reported attended her funeral!

So, if 150 is the number of people we natural associate with, we have a fundamental challenge when our organisation grows beyond that size. Our brains are just not large enough to associate with and gain identity in 2,000-, 20,000- or 200,000-people organisations. Our brains are not large enough to manage the social and political complexities in group sizes significantly beyond 150. Therefore in large organizations, people are naturally going to associate with their department, subsidiary or geography of a human scale of around 150.
And in small organisations that grow toward and beyond 150, people will start to say, “It’s not as friendly as it used to be,” and, “We don’t know everyone like the old days.”

Reason 2 – Hierarchy
Silo behaviour is strongly impacted by the behaviour of the top team. Members of the executive team are members of two teams – the one they lead and the executive team itself. Their personal association to both teams should be balanced, tilted slightly in favour of their membership of the executive team. Often, however, members of the top team associate primarily with their role as the leader of their unit. After all, as leaders of their own unit they are the alpha individual. However, the corollary is that they have little emotional connection with their colleagues on the top team, even to the extent of merely humouring each other and paying lip service as members of the top team. In this case, membership of the top team becomes ceremonial and the individuals’ real identity is with their unit, and the foundation condition for a culture of silo and turf protection is established.
Reason 3 - Similarities

We naturally relate to people like us. So after an organisation grows beyond 150, the sense of belonging will move away from “us” as a single community into a series of “us and thems” where belonging is mostly between like-minded groups. This is often around professional groupings of people with a shared outlook. The result is geographical or functional silos where say, Regions criticise Head Office, HR argues with Finance. Sales doesn’t see eye-to-eye with Marketing, and Manufacturing just doesn’t understand Engineering and vice-versa. Group rivalry, arguments and misunderstandings result.

Being a hierarchal social animal, chimpanzees display similar group behaviours.
Firstly, brain size drives the size of chimpanzee communities. Chimpanzees are pretty brainy and, after humans, have the second largest brain per body size of any animal. On Dunbar’s graphic plot of brain per body ratio the prediction is that chimpanzees in the wild live in groups of around 55, which is indeed the case. Chimps are not brainy enough to live in groups of 150, so for them their magical number is group size of 55.
Second, chimps display strong “them and us” behaviours. In studying the Gombe chimps in Tanzania, at one point Dr Jane Goodall observed the community fracture into two groups, perhaps due to the increased population beyond the natural sized group. A smaller breakaway group took up occupation of a neighbouring territory. Competitive group rivalries boiled over into brutal warfare. Over the two years following the breakaway, the main, established group hunted down and killed all members of the splinter group. And these were individuals that up until recently had been part of their community.
While in organisational life our response might be more subtle, the intent is not such a long way from the Gombe chimp actions – we become protective of our in-group, we battle for resources, and conflicts can be more emotional with groups that we should by rights be friends with!

Case Studies

Some organisations consciously manage the significance of the 150 group size and natural siloing.
Gore Associates is often credited as one of the best managed companies in the US. Reportedly, one of Gore’s planning disciplines is to build facilities with car spaces for only 150 cars. When the car park is nearing capacity, it’s time to build a new facility.
Flight Centre is an Australian based business in the travel sector. Flight Centre is frequently awarded best employer status in different countries and claims that a critical aspect of its success is basing its organisational structure on human instinct principles. The company drives a sense of both identity and accountability through a first-level structure of family groups of up to seven people and a geographic unit of around 80-100 people. Flight Centre encourages strong bonds, identity and healthy rivalry of the human-sized subgroups. In turn, an individual’s strong sense with family, village and tribe translates to a strong sense of identity with the organisation of 14,000. (The story of Flight Centre is well told by ex-insider, Mandy Johnson in Family Village Tribe – The Story of Flight Centre Limited, Random House, 2005).

Actions to reduce silos

Given that for medium to large organisations, soloing will naturally emerge, what can leaders do to contain the negative aspects of intra-group rivalries and competition?
1. Structure according to preferred silos

Given that a perfect world free of silos is unlikely, organisations should be structured to align people to the most preferred group identity. What reporting lines will reflect the clanning you most want? And can you accept the consequential tensions and competition this structure might create? Seek to structure your organisation in natural groups that generate the most energy for group members.
2. Build social collegiality amongst the top team

To reduce silos, the CEO needs to build a team spirit where executives have a strong sense of team. If the top leader does not build the emotional collegiality amongst the top team, then they drive the social belonging of the individuals to the level below them. Often, because the CEO has little need for collegiality, they unwittingly increase the likelihood of silo behaviour. Build the emotional connection amongst the top team.
3. Regularly switch the roles of the top team
To avoid executives being selfishly devoted to their role as a unit leader, regularly change the roles of the top team. Head of HR becomes head of Customer Service. Head of Sales becomes head of Marketing. The outcome is that the individual leaders know that their primary purpose and identity is in their membership of the top team and less so the portfolio that they happen to be responsible for right now. Moving to another function also of course allows the executive member to be more appreciative of the work of the new function.

4. Value every group equally
CEOs often value one group in their organisation more than others. This drives feelings of elitism of the one favoured department and resentment as second-class citizens amongst the rest, with consequential “them and us” competition and jealousy. Ideally, as one particular CEO I know did, the top leader demonstrates the value of all sections of the organisation; like all parts of the human body contribute to a healthy, functioning system and not just the high-profile organs of the heart and the brain (the lower bowel might not have a glorious job, but try to operate for long without it).
5. Attend to destructive behaviour

Top leaders should not accept destructive, competitive intra-group behaviour. The CEO should specifically make clear that competitive group behaviour will not be tolerated, and if it appears, address it immediately. If a member of their team persists in destructive behaviour, the CEO needs to make the choice for them by moving them out of the top team. If the CEO does not make this a requirement of group membership, then in organisations beyond 150 we can predict that silo behaviour will be destructive and systemic. It’s a choice of the CEO and is an appropriate use of their power as the head of the hierarchy.


Andrew O'Keeffe is a Human Resources Executive. He has observed bosses for many years, has worked for bosses and has been a boss. As a result of these studies he has written one of the very best leadership books ever, called 'The Boss'and recently released 'Hardwired Humans'.

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