WHY GOSSIP IS GOOD FOR YOU
Humans live in much larger groups than other primates. Language may have evolved as a form of grooming to allow us to live with so many people.
HUMANS are fascinated by what other people get up to. The success of
the tabloid dailies is ample proof of that. But why should we find tittle-tattle
about the private lives of minor celebrities, royalty and politicians of
such overwhelming interest that it can drive the starving children of Somalia
and the war-ravaged cities of former Yugoslavia off the front pages of
even the most sedate of newspapers? The answer seems to lie in the evolutionary
roots of our large brains.
As far as absolute brain size goes, humans don’t have the largest brains
in the animal kingdom; that privilege goes to whales. But, relative to
body size, primates have much larger brains than any other animals, and
we humans, not surprisingly, have the biggest brains of all—about six times
larger than you would expect for a mammal of our size.
Why do primates have such big brains?
There are two general kinds of theories. The more conventional one
is that they need big brains to help them to find their way about the world
and solve problems in their daily search for food.
The alternative type of theory is that the complex social world in
which primates live has provided the impetus for the evolution of large
brains. The main version of the social intelligence theory, sometimes known
as the Machiavellian intelligence hypothesis, has the merit of identifying
the thing that sets primates apart from all other animals—the complexity
of their social relationships.
Primate societies seem to differ from those of other animals in two
key respects. The first is the dependence on intense social bonds between
individuals, which gives primate groups a highly structured appearance.
Primates cannot join and leave these groups as easily as animals in the
relatively amorphous herds of migrating antelope or the swarms of many
insects. Other species may have groups that are highly structured in this
way—elephants and prairie dogs are two obvious examples—but these animals
differ from primates in a second respect. This is that the primates use
their knowledge about the social world in which they live to form more
complex alliances with each other than do other animals.
Keeping track of relationships
This social intelligence hypothesis is supported by a strong correlation
between the size of the group, and hence complexity of the social world,
and the relative size of the neocortex— the outer surface layer of the
brain that is mainly responsible for conscious thinking— in various species
of nonhuman primates. This result seems to reflect a limitation on the
number (and/or quality) of relationships that an animal of a given species
can keep track of simultaneously. Just as a computer’s ability to handle
complex tasks is limited by the size of its memory and processor, so the
brain’s ability to manipulate information about the constantly changing
social domain may be limited by the size of its neocortex.
In evolutionary terms, the correlation in Figure 1 suggests - that it
was the need to live in larger groups that has driven the evolution of
large brains in primates. After all, group size is flexible, and often
variable, within a given population but increases in brain size would only
come about if they offered an evolutionary advantage to a species. There
are several reasons why particular species might want to live in larger
groups, not least protection against predators. And it is conspicuous that
the primates which both live in the largest groups and have the biggest
neocortices are species such as baboons, macaques and chimpanzees that
spend most of their time on the ground and live either in relatively open
habitats, such as savannah woodlands, or on the forest edge where they
are exposed to much higher risk from predators than most forest-dwelling
This relationship between neocortex and group size in the nonhuman primates
begs an obvious question. What size of group would we predict for humans,
given our unusually large neocortex? Extrapolating from Figure 1 gives
a size of 148. But is there any evidence to suggest that groups of this
size actually occur in humans? On the face of it, things do not look promising.
After all, in the modern world, we live in huge nation states containing
tens of millions of individuals. However, we have to be a little more subtle:
the relationship for nonhuman primates shown in Figure 1 is concerned with
the number of individuals with whom an animal can maintain a coherent relationship
It is quite obvious that those of us living in, for example, Britain
do not have personal relationships with every one of the other 55 million
inhabitants. Indeed, the vast majority of these people are born, live and
die without ever knowing each other’s names, let alone meeting. The existence
of such large groupings is certainly something we have to explain, but
they are something quite different to the natural groupings we see in primates.
One place we might look for evidence of “natural” human group sizes
is among pre-industrial societies, and in particular among hunter-gatherers.
Most hunter-gatherers live in complex societies that operate at a number
of levels. The smallest groupings occur at temporary night camps and have
between 30 and 50 individuals. These are relatively unstable, however,
with individuals or families constantly joining and leaving as they move
between different foraging areas or water holes. The largest grouping is
normally the tribe itself, usually a linguistic grouping that defines itself
rather strictly in terms of its cultural identity. Tribal groupings typically
number between 500 and 2500 men, women and children.
These two layers of traditional societies are widely recognised in
anthropology. In between these two layers, however, is a third group often
discussed, but seldom enumerated. Sometimes, it takes the form of “clans”
that have ritual significance, such as the periodic celebration of coming-of-age
ceremonies. Sometimes, the clan is based on common ownership of a hunting
area or a set of water holes.
Finding the right groups
For the few cases where census data are available, these clan groups
turn out to have a mean size of about 153. Figure 2 shows all the data
I have been able to collate from the literature on traditional societies.
In addition to traditional hunter- gatherers I also included settled hunter-gatherers
and simple of the village and clan-like groupings for these societies fall
between 100 and 230, which is within the range of variation that, statistically,
we would expect from the prediction of 148. In contrast, the mean sizes
of overnight camps and tribal groupings all fall outside these statistical
But what about our own society? Is there anything to suggest that the
figure of 150 might be a relevant social unit? The answer is yes. Once
you start to look for them, groups of about this size turn up everywhere.
In most modern armies, for example, the smallest independent unit is the
company, which normally consists of three fighting platoons of 30 to 40
men each plus the commander’s staff, making a total of 130-150 men. Even
the basic fighting unit of the Roman Army during the Republic was of similar
size, containing exactly 130 men. The same figure turns up in businesses.
A rule of thumb commonly used by managers is that companies smaller than
150 work fine on a person-to-persor basis, but once they grow large than
this they need a formal hierarchy if they are to work efficiently. Sociologists
have known since the 1950s that there is a critical threshold in the region
of 150 to 200, with larger companies suffering a disproportionate amount
of absenteeism and sickness. In 1989, Tony Becher of the education department
of the University of Sussex published a survey of 12 disciplines in both
the sciences and the humanities. He found that the number of researchers
whose work an individual was likely to pay attention to was between 100
and 200. Once a discipline becomes larger than this, it seems that it fragments
into two or more subdisciplines.
There are other interesting examples. Neolithic villages from the Middle
East around 6000 BC typically seem to have ^contained 120 to 150 people,
judging by the number of dwellings. The Hutterites, a group of contemporary
North American religious fundamentalists who live and farm communally,
regard 150 as the maximum size for their communities. What is interesting
is the reason they give for splitting communities at this size. They find
that when there are more than ut 150 individuals, they cannot control the
behaviour of members by peer pressure alone.
These are just a few of the examples from a great deal of sociological
and anthropological evidence which suggest that “natural” groupings of
about 150 individuals do occur in human societies, and that it is possible
for individuals within such groups to maintain a coherent set of relationships
through time by direct contact between individuals. The fact that the “natural”
group might be as large as 150 raises some interesting questions about
how such large groups are kept together. Among primates in general, and
the Old World monkeys and apes in particular, social grooming is the main
mechanism used to cement relationships between individuals. Moreover, the
amount of time devoted to grooming other individuals is proportional to
group size, at least within the Old World monkeys and apes. Those living
in large groups of about 55 animals (essentially baboons and chimpanzees)
spend up to 20 per cent of their day in this activity. Extrapolating from
these data, we find that the amount of time required to maintain cohesion
within a group of 150 would be something in the region of 35 to 45 per
It is doubtful whether any species that has to search for food daily
could afford to spend almost half its day in social interaction. How then
could the ancestral humans have ensured the proper degree of bonding within
such large groups?
Cost of grooming
The main problem with social grooming is that it is costly in terms
of time. A monkey can only groom one individual at a time, and grooming
cannot easily be combined with eating, travelling between feeding sites
or other essential activities. The baboons and chimpanzees, for whom grooming
consumes 20 per cent of their time, are probably already operating at the
limits of their capacity. Any increase in group size can only come through
a shift in gear in the mechanism used for social bonding. For humans, that
shift in gear may have come in the form of language.
Language has two interesting properties compared to grooming: you can
talk to several people at once and you can talk while travelling, eating
or working in the fields. Conventional wisdom has always supposed that
language evolved to enable humans to exchange information about food sources
and to aid cooperation during hunting. But it is difficult to see why humans
should be any more in need of this than other primates or, if hunting is
the issue, the social carnivores such as lions and wolves. A more plausible
suggestion is that language evolved to enable humans to integrate a larger
number of individuals into their social groups.
Some evidence to support this comes from the number of people it is
possible to have a conversation with. If language really is just a form
of vocal grooming designed to service a larger number of relationships,
then its efficiency relative to grooming should mirror the ratio of the
size of human groups to the largest found among primates—55 in chim- panzees
and baboons. If human groups are typically about 148, then speech should
be 148/55 times more efficient than grooming as a bonding mechanism. Given
that grooming is limited to a one-to-one relationship, this should mean
that language should make a 1:2.7 ratio possible. In other words, while
monkeys are limited to grooming in pairs, human conversation groups should
consist of an average of 3.7 individuals (one speaker 2-7 listeners).
And indeed do.
The sizes of conversation groups in a student refectory, for example,
consist of an average of 3-4 individuals, with a striking tendency for
groups larger than four to fragment into two or more smaller conversation
subgroups. Interestingly, there turns out to be an accustical limit on
conversation group sizes. Measurements of sound level of speech over distance
indicate an upper group for conversation of about five people. If the group
gets larger than this, individuals are forced to stand in too large circle
to be able to hear everyone clearly. Thus, the characteristics of speech
seem to be closely ried to the size of the interaction group required to
Importance of a good gossip
There is, of course, another way in which language allows us to integrate
a large number of social relationships, and that is by allowing us to exchange
information about other individuals who are not present. In other words,
by talking to one person, we can find out a great deal about how other
individuals are likely to behave, how we should react to them when we actually
meet them and what kinds of relationships they have with third parties.
All these things allow us to coordinate our social relationshhips within
a group more effectively. And this is likely to be especially important
in the dispersed groups that are characteristic of humans.
This could explain our fascination for social gossip in the newspapers,
and why gossip about relationships accounts for an overwhelming proportion
of human conversations. Even conversation in such august places as university
coffee rooms tend to wing back and forth between academic issues and gossip
about individuals. To get some idea of ow important gossip is, we monitored
conversations in a university refectory, scoring the topic at 30-second
intervals. Social relationships and personal experiences accounted for
about 70 per cent of conversation time. About half of this was devoted
to he relationships or experiences of third parties (people not present).
Males, however, tended to talk more about their own relationships and experiences
whereas females tended to talk most about other people’s.
This is interesting because it can be interpreted as suggesting hat
language evolved in the conext of social bonding between females. Most
anthropologists have assumed that it evolved in the context of male-male
relationships, during hunting for example. The suggestion that female-female
bonding, based on knowledge of the relationships of
other individuals, was more important fits much better with views about
the structure of nonhuman primare societies where relationships between
females are all- important.
That conversations allow us to exchange information about people who
are not present is vitally important. It allows us to teach others how
to relate to individuals they have never seen before. Combined with the
fact that language also makes it easy to categorise people into types,
we can learn how to relate to classes of individuals rather than being
restricted to single individuals as primates are in grooming. For example,
we can give types of individuals special markers, such as dog collars,
white lab coats or large blue helmets, which allow us to behave appropriately
towards them even though we have never met before. Without that knowledge,
it would take us days to work out the basis of a relationship.
Classifications and social conventions allow us to broaden the network
of social relationships by making networks of networks, and this in turn
allows us to create very large groups indeed. Of course, the level of the
relationship is necessarily rather crude but at least it allows us to avoid
major social faux pas at the more superficial levels of interaction when
we first meet someone. Significantly, when it comes to really intense relationships
that are especially important to us, we invariably abandon language and
revert to that old-fashioned primate form of direct interaction—mutual
What we seem to have here, then, is a new theory for the evolution of
language that also seems to account for a number of other facets of human
behaviour. The theory explains why gossip about other people is so fascinating;
it explains why human societies are so often hierarchies; it predicts the
small size of conversation groups; it meshes well with our general understanding
of why primates have larger brains than other mammals, and it agrees with
the general view that language only evolved with the appearance of Homo
What it does not explain, of course, is why our ancestors should have
needed to live in groups of about 150. It is unlikely that this has anything
to do with defence against predators (the main reason why most nonhuman
primates live in groups) because human groups far exceed the sizes of all
other primate groups. But it might have something to do with the management
or defence of resources, particularly dispersed resources such as water
holes that nomadic hunter-gatherers might have had to depend on at certain
times of the year.
Robin Dunbar is professor of biological anthropology at University