THE most fundamental questions for all organizations are about numbers. Is there a point when economies of scale are negated by the costs of bureaucracy and alienation? How many people can you admit to a meeting before it becomes a waste of time? What is the optimum size for a committee? Or a panel? Or a board?

Robin Dunbar is a British psychologist and evolutionary biologist who has been thinking about the question of numbers throughout his career (and who was once accorded one of the highest honors in the scientific world, that of being mentioned in The Big Bang Theory). While studying our nearest biological kin, apes and chimpanzees, he came across the “social brain hypothesis.” What sets primates apart from other mammals are the large, cohesive social groups based on bonded relationships (individuals form close friendships with each other) that they inhabit. Such relationships depend on the ability of animals to figure out how others will behave and how to interact with predicted behavior. That skill requires considerable computational power — in other words, a big brain. The social brain hypothesis dictates that the size of the group that primates form will be limited by the average size of their brains. For humans the group size is 148 — or 150 for convenience.

Having hit on the magic number, Dunbar noticed that it kept coming up everywhere. Hunter-gatherer communities — the communities in which human beings primarily lived until around 12,000 years ago — tended to consist of about 150 people. The basic unit of modern armies is 150. Oxbridge colleges traditionally had between 100 and 200 members. Hutterite and Amish religious communities split up when they reach 150 and “plant” new colonies. Most people maintain a close personal network of about 150 “friends and family.” These are the people that they see on a regular basis and would go out of their way to help. Outside that magic number the ties are much looser and the sense of obligation less telling.

Dunbar then went on to discover various smaller numbers that hold significance in human relationships: Five represents the number of close relationships that a person can have; 15 represents the number of people who can be considered best friends; 50 represents your main social circle, the number of people you would invite to a big garden party or major birthday.

In The Social Brain: The Psychology of Successful Groups, Dunbar has teamed up with two Oxford University colleagues at the Said Business School, Tracey Camilleri and Samantha Rockey, to apply his insights to the business world. The authors not only explain the importance of getting the numbers right for various business processes. (Given this focus on optimal group size, the unconventional choice of three authors is left frustratingly unexplained. Surely most co-authors of books choose to write with just one partner for a good reason.) They also draw lessons from evolutionary biology about how to make sure that groups of various sizes work well together.

The authors emphasize the importance of matching the size of the group to the task at hand — something that ought to be obvious but is ignored with surprising frequency. If you need to make decisions fast, as in crisis management or creative development, five is a good number. (An analysis of 58 software development teams found that the five most successful teams averaged 4.4 members while the five least successful ones averaged 7.8 members. Five also provides a natural tie-break.) If you want to make complex decisions, then 12 to 15 is a better size, since it provides more perspectives. Work groups can contain six to 12 people, provided that each person knows his or her role and the agenda is clear. Fifty is a good number for an information-sharing meeting if you have a clear leader and a fixed agenda. Fifty is also the maximum number at which it is possible to run a “community of practice” along simple democratic lines without a formal management system in place.

The cost of ignoring these numerical constraints can be seen everywhere in business. Oversized board meetings fail to provide proper oversight. Oversized crisis management teams bicker while the company burns. Oversized meetings of all kinds allow bores to hold court while most people check their phones — or else dissolve into a cacophony of competing voices as everyone tries to have their say.

The authors also make much of the dangers of gigantism. Chris Cox, who was chief product officer at Facebook back in 2005 when the company had fewer than 100 employees, told a meeting of the Aspen Ideas Festival in 2019 that “I’ve talked to so many startup CEOs who say that after they pass this number [150 employees] weird stuff starts to happen.” Patty McCord, a former chief talent officer at Netflix, talks about a “stand-on-the-chair number”: If you stand on a chair and shout and people still can’t hear you, then you know you are in the realm of “weird stuff” starting to happen. You need to rethink how you are organized.

The danger is that companies will be so focused on economies of scale that they lazily add more managers without recognizing the costs this exacts in bureaucratization, alienation, and free-riding. Faces disappear into the crowd. Meetings multiply and metastasize. People become functions (“marketing,” “product and development”). “We” becomes “us” and “them.” Modish practices such as hot-desking only add to the sense of alienation and impersonality. Intelligent companies work hard to avoid this by breaking themselves into smaller units — that is “growing large by staying small.”

It turns out that several companies instinctively hit on the problems of the “Dunbar number” before Dunbar himself did. When Wilbert (Bill) Gore established W.L. Gore and Associates with his wife, Genevieve, in 1958, he limited the size of his plants to 150 because he had seen the costs of alienation when working for a multinational. (The average size of plants is now closer to 250 than 150.) The Mars family was so keen on capping the size of the company’s headquarters at 50 that one member of the family routinely counted all the punch cards (even the CEO had to punch in until 2008) and raise the alarm if more than 50 were there. (Since the company’s acquisition of Wrigley in 2008, the size of the global HQ has been raised to 100.)

The authors also suggest that companies should use the insights of evolutionary biology to build and reinforce the social bonds that make companies function well. This starts with eating together (the word “company” comes from the Latin “companion” meaning “bread fellow” or someone you break bread with.) The great feasts of Oxford colleges and City guilds are not acts of self-indulgence, as they might appear, but highly effective bonding rituals that ease the flow of ideas and commerce. It extends to other sorts of bonding. Many Japanese companies get their employees to perform group exercises at their desks every morning, and hold nomikai (drinking parties) at night. IBM once obliged its employees to sing company songs. Some Silicon Valley companies hold rock concerts — or at least they did before the new “back-to-basics” ethic swept through the valley. The post-COVID fashion for working from home means that companies will have to redouble their bonding efforts.

Our authors are rather too keen on repeating the same points over and over rather than exploring possible objections. The human scale imposes costs as well as benefits. Anthony Trollope wrote immortal novels about the feuds that split asunder the small clerical world of Barchester. Oxbridge colleges are notorious for the internecine quarrels which can have big-brained intellectuals behaving like squabbling children. Christ Church, one of the grandest Oxford colleges, was recently consumed by a squabble between the college head, Martyn Percy, and the college fellows (or Students as they are called) that was so vicious, sustained, and frankly demented, that Percy considered committing suicide and the Charity Commission denounced the college for mismanagement and misconduct. Family companies suffer from more value-destroying feuds than public companies because they mix family tensions with pecuniary gain, as viewers of the hit series Succession know all too well.

Small institutions also have the habit of becoming nests of sybarites unless they are subjected to external discipline. Edward Gibbon famously complained that he learned nothing at Oxford because the tutors at his college, Magdalen (which also happens to be Dunbar’s college), were “sunk in port and prejudice” and almost completely indifferent to education, whether applied to their students or themselves. The university only became a center of excellence when 19^th century reformers forced it to select its fellows based on open competition rather than “founders kin” and personal connections. Sensible family companies bring in external managers to add not just professionalism but also perspective. Sometimes you must fight against natural instincts such as nepotism to bring out the best in human potential.

Our authors are particularly frustrating on the question of diversity. They point out that human beings have a natural tendency toward homophily — they naturally seek out those who share their interests and experiences. Homophily efficiently deals with organizational gremlins such as building trust and promoting mutual understanding: hence the success of institutions that have traditionally drawn their members from a narrow range of backgrounds such as the Guards or Christie’s. But they also blandly endorse the current vogue for diversity. They may well be right that the value of diversity in bringing different perspectives is dispositive — that the juice is more than worth the squeeze, to borrow a phrase, as it was when the inbred Oxford colleges that Gibbon condemned were forced to introduce open competition. But it’s negligent at best and cowardly at worst to praise both homophily and diversity without examining the tension between the two.

This habit of dodging difficult questions is particularly annoying because The Social Brain is otherwise intellectually brave. Management science has always had a weakness for what the English literature don (and notorious misfit) F.R. Leavis called the “technologico-Benthamite reduction of human experience to the quantifiable, the measurable, the manageable.” Management theorists assume that the best way to motivate people is to reward them with carrots and punish them with sticks. This was the basis of Frederick Taylor’s theory of scientific management in the early 20^th century and formed the basis of shareholder maximization theory more recently. Various attempts to embrace “scientific management” with more humanistic management have failed because humanistic management rapidly degenerates into kumbaya-singing twaddle.

But evidence is mounting that carrot-and-stick management is poor at promoting long-term loyalty because it fails to reckon with things like people’s pursuit of meaning and belonging. The Social Brain represents an interesting attempt to factor in the importance of meaning and belonging without indulging in twaddle. The authors rightly point out that the machine metaphors that still dominate management thinking (“well-oiled,” “leverage,” “nuts and bolts”) look old-fashioned in a world of super-fast computers. They also argue that it is perverse for people who are concerned with managing and motivating individuals not to take advantage of what evolutionary biologists have discovered about “what is unchanging in the ways human beings behave” — as if humans are blank slates to be written on at will rather than particularly intelligent members of the mammal family. “We have non-negotiable constraints,” they argue, “linked to brain size, time and underlying hormonal responses.”

The Social Brain makes a good start in outlining some of the valuable lessons managers can learn from biology. Many more lessons will come as management theorists, exhausted by both the failure of techno-Benthamism and the vacuity of its humanistic alternatives, start to reckon with the explosion of knowledge in the biological sciences.

BLOOMBERG OPINION