Grooming, Gossip, and the Evolution of Language


Robin Dunbar


Harvard University Press

Cambridge, Massachusetts




Language developed to facilitate an increase our group size.  We have a huge brain size to body ratio.  In primates, the larger the group size, the larger the frontal lobe.  Our frontal lobe predicts a group size of about 150.  Many sources of evidence confirm that as an ideal group size for us.  Or as the author states on 192 . . .


The central four points are:

1)     Among primates, social group size appears to be limited by the size of the speciesÕ neocortex.

2)     The size of human social networks appears to be limited for similar reasons to a value of around 150.

3)     The time devoted to social grooming by primates is directly related to group size because it plays a crucial role in bonding groups; and finally,

4)     It is suggested that language evolved among humans to replace social grooming because the grooming time required by our large groups made impossible demands on our time.  Language allows us to use the time we have for social interactions more efficiently.


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3 – By the age of 6 the average child has 13,000 words. That is 10 words a day since its first birthday.


5 – fiction dominates our book shelves.  It is one half of our reading, all else, science, sports, photography, history, is all relegated to non-fiction.


6 - Even prestigious papers like the times devote much of their paper to gossip.




10 – Our common ancestor with the chimpanzee lived 5 to 7 million years ago.


13 – Some 10 million years ago temperatures plummeted and forests retreated.  And around 7 million years ago our ancestors started to spend more time in the Savannah.


16 – They had to avoid being prey so they got bigger and started spending time in groups.


18 - So mutual defense is at our heart, our sociability a survival mechanism.


21 – Chimps groom to keep track of each other.  How much females support each other (when they accidentally stray into another harem) is predicted by how much they groom.


23 – But they also use their social skills to exploit each other.  A juvenile got his mother to attack a male ape who had just dug up a tuber, in order to get that tuber.


24 – When they strategize coalitions to be alpha male, Chimps take otherÕs intentions into account.


25 – 34 Basic Darwinism.




35 – Primates are constantly in drama land and watching what others are doing. They groom for 10 – 20 percent of the day.


36 - It slows their heart rates and stimulates our natural opiates, endorphins.  If given morphine, grooming is suppressed.  It cements bonds of friendship.


40 – living in larger groups creates increased competition for food. Big thugs get more food and better position.  Lower ones get harassed and this stress can lead to depression, disease, and infertility.


41 – This can lead to half an offspring less over a life time in females.


42 – Stress can delay puberty.


43 – Human malesÕ sperm count goes down during exam time. 


The solution to this mayhem is coalitions. That allows you to defuse the opposition without driving them away.


45 – Grooming is a high-cost expression of fealty that deters free riders.


46 – In many species, the female will only mate with males who bring them gifts.


47 – They recognize each otherÕs chatter.  If having illegal sex and a low level monkeyÕs voice is played, chimps ignore it. High level gets them to hide.


49 – When a female gives birth, monkey females chatter with excitement. We may be missing the point when we try to teach primates our language with grammar. Language is a social cue.  Still the results have been disappointing.  Why are we so good at language?




57 – Primates have very big brains for their body weight, bigger than all other species.  Ours is 9 times that of other mammals.


62 – Group size correlates with neocortex size (after correcting for body size). But it is not just group size, but quality of social relations in the groups.


68 – Verbet monkeys pay more attention to distress calls from animals they have recently groomed. Group size increases the number of folks needing grooming.


69 – Our group size predicts groups of about 150.  Human groups are, though, flexible.  We see groups of 30 -35 as a core of overnight campers.  When they all come together, the largest groups are 1500 – 2000.  This is a tribe, defined by linguistic commonality (language or dialect). Below this are mega-bands of 500 people.  And, below this are clans of exactly 150!  They are less variable in size than any other group. 


71 - Clans get together once a year to organize rites of passage for males, to contract marriages and do old rituals. They know family relationship histories. It is the largest group in which everyone knows each other.


It is the number of descendants an ancestral couple would have after 4 generations. So it is the largest group anyone would personally know of, including cousins.


Villiages of 5,000 bc were around 150, around the world. And after 150 sociologists tell us that groups become more hierarchical.


75 – During WWI I company sizes stabilized at 170. 


76 – There is also the sympathy group size of 11 – 12.  It is the size of folks who would find your death devastating; folks you contact at least once a month. But in conversation we can groom several folks simultaneously.




84 - Humans can keep up on 6 orders of intentionality.  I think that sheÕs angry that I work: this is 3 orders of intentionality.  This is a measure of the Theory of Mind (TOM). Not until 4 ½ do children understand that others have a mental state other than theirs (2nd order of intentionality).  Up to 3 children cannot lie. Apes see themselves in mirrors. 2 hid orgasm sounds from hierarchy male when speaking.  Chimps do 2nd order intentionality.


The leap from guessing othersÕ intensions to asking about our personal mind was impactful.  Then to ask questions about a 3rd person!  Wow!  Science and religion are impossible without this.  They need the ability to treat the world as separate and with some order irrespective of our mind.  And the idea that we can tease out its logic.  These are 3rd order intentionality. 


Thoughts happen without language.  Apes have thought, but no language. Language seems to be parasitic on thought.  Subject, verb, object, reflects thought.    If chimps have religion, it must be individual because it cannot be communicated. 


90- Aspergers.


91 – Chimps, gorillas, and orang-utans recognize themselves in mirrors.  But no monkey has ever passed the test.  


96 – Chimps use deception to get what they want – perhaps to a 4th level of theory of mind.  He things (102) 3rd order intentionality.


101 – Theory of mind likely started when we got the ability to peer back at our own minds. I am hungry.  Why do I feel the way I do? This is very necessary for religion and science – they describe the world from afar.


102- A high level of intentionality is necessary to write novels.  You must know who did what and assume that the reader can follow.


104 – Science and religion require 4th level intentionality, that is why no primates have them. Only apes strive past 2nd, so they alone, other than us, may create religion.




107 - We stand to get across to increasing savannahs. Standing gets us more cooling air and 1/3rd the direct sunlight and more wind and so less hair.  Hair is an insulator.  It keeps you warm. No hair allows evaporation of sweat and cooling you.  Beards and hair block direct sun-burning. 


108 - This doubles the distance we can travel on a pint of water.  Lucy is 3.3 million years old and walked mostly upright.


110 – This exposed us to danger of predators.  So we grew in size and our groups got bigger.  Lucy was barely four feet tall.


So when does language start?  Archeologists say 50,000 years ago.  Anatomists, 250,000 years ago (when brain asymmetry is apparent).


100,000 years ago our group size got much bigger and reached 150.  But it was at 120 by 250,000 years ago.  And, 115 500,000 years ago.  It seems to have evolved in three stages; basic with the appearance of homosapiens, then two bumps.


120 - Why did we need bigger groups?  Defense against predators. Defending food against other homo sapiens?  A nomadic lifestyle that required some treaties, and so communication?  He goes for the latter but isnÕt sure.


Why are groups 150?  Check parties.  You can groom 3 people with words: 3 listeners.  Real grooming is one on one.  So 3 rather than 1.  Chimp communities are 55 on average.  Which is 1/3rd smaller than 150 (the human social group predicted by our frontal lobe size).  3 times the grooming capacity and three times the group size.  Coincidence?


People hear best at 2 feet (3 max conversationalists) and at 5 feet there is a big drop off.  The loudness with which cultures speak is inversely related to the number of vowels in the language.  Groups that donÕt like closeness, shout.


So language as groomer would predict group sizes of 150 and that we spend lots of time on gossip.  Both are true. 


Groups that stay spread out have fewer vowels. 

This explains German consonants and love of distant impersonal systems.  French vowels and love of close personal detail oriented art.


124 -  Our brain being 8 time primate and 9 times general animal proportions, takes a lot of energy. The other big consumers are heart, kidney and gut.  One must take less energy more for the brain to take more.  The gut is the one.  We have small guts and we compensate by eating nutritious foods, not leaves.

125 - Animals digest poor food for a long time and so rest a lot.


127 - Australopithecus ate vegetation.  We homos switched to meat about 2 million years ago.  This allowed for larger brains. 


128 - Other mammals give birth to babies with full blown brains.  Ours is 1/3rd its final size at birth.  Premature.  It grow  until 12 months.  This meant males had to spend more on raising the kids.  Our size (body and teeth) advantage over women decreased.


130 - Harem owning mammals are larger and have bigger teeth and canines. Early homos were like this.  [How about polygamous populations today?]  But males would have trouble providing meat for more than two.  Perhaps that is why our bodies are more polygamous than our practices.




133 – Fine motor skills needed to throw and the fine skills needed to speak are both in the left hemisphere.


What of the origins of language?  Did it come from gestures?


 Monkeys have round dog like chests.  Apes flat.  Animals that walk on all 4 have restricted breathing patterns.  Apes shoulders being back allows the shoulders to let arms go 360 degrees therefore they can swing from trees.


134 - Our flat chests allow for easier breathing and more breathing control. It also allows fine-tuned throwing.  This is important for hunting. 


The problems with this gestural origin of language is that speaking and throwing are very different.  And, how do we get complex gestures sans the thoughts. Gestures donÕt really do abstract concepts.   It also requires that weÕre close to people to communicate.  And, that doesnÕt work with larger groups.


136 – Then why are speech and throwing on the same side?  He says cause the right side was busy.   It does emotions. Emotional cues are discovered quicker when on the left side of the face. 


Even going back to trilobites, some 250 million years ago, there are more scars on the right.  Meaning the attack came from the left.


137 - Right side being spread we put people in our left visual field when we fight.  We need to see their intentions.  We take photos on our right sides.


 138 - Babies are cradled on the left.  For the right brain emotional reading ability.  Language happens in the left hemisphere, cause it is empty.  


139 – Julian Jaynes!!!  He noted that lit from 1200 is unemotional. It is straightforward narrative.  That would mean language gradually exerted more control over the right side.   This likely confounds two happenings: the growing dominance of the left (which must have accompanied language evolution) and peoples ability to give expression to their emotional states.


Untrained musicians recognize tunes better if played to the left ear. The emotional reaction to music and rhythm happens on the right side.


140 – This means that the idea that language evolved from song cannot be right. Song engages emotions more than words alone can. More likely, when language evolved, it was hijacked by the emotionally powerful music centers to create song. 


Since vervet monkeys and such have language and no gestures, we neednÕt hypothesize language came from gestures.


143 - People express more extreme views in groups. 


144 – We give way to bigger animals, and lower voices indicate size.


145 – Hitler and Thatcher lowered their voices for speeches.


146 – Trying to hold a group together, of 150, must have been hard. Words are not emotional enough.  Song and dance work.


147 – But he doesnÕt think language evolved to make ritual possible.  He thinks social bonding was the cause, and music and ritual hijacked it. And, he thinks it happened in the Upper Paleolithic.


148 - n most primate species it is the females that form the core of society.  They create the group and give it coherence.  Males walk from group to group.


Nowadays we see the opposite in early tribes.  But, the closeness of X-Chromosome genes suggests women strayed less than men. Female chimps have longer relationships than men.


Words are unemotional.  In courtship we use them.  But some are later must be moral direct stimulation, which releases opiates and is therefore emotional to bond.


Females create the group.  They may have made language to get men to invest more in them and the offspring.  This is backed by womanÕs current strength in the social and verbal domains . We often refer to co-religionists as brothers and sisters.   Thus follows a discussion on our desire to help relatives.  ŌMotherlandĶ is to convince us of relation. 




Languages diversity and become mutually incomprehensible quickly. 


155 – The super family language, Nostratic, the father of Indo – European and some Asian languages came about 13,000b.c.


157 – Today there are 5,000 languages spoken.


158 – Colin Refrew sees language spreading out in 4 major migrations.  That of 100,000 years ago.  Then another 10,000 ago following the development of farming in the New and Olds Worlds.   Then about 8000 years ago with global warming and the end of the Ice Age. Then the spread of the Mongols. 


161 – DNA seems to verify this. 

Our common female ancestor probably lived 150 – 200,000 years ago.  


162 - Close dialects are highly correlated with relatedness.  As Hamilton showed, we prefer to live next to and help kin. 


164 - A badge that is hard to fake.  This protects against free riders on a successful effort.  Those who would exploit folks national cooperativeness.  In places with more people, it seems languages must diversify more quickly. 


165 - Vikings were less likely to kill relatives than others.


166 – Children die from step-parents 60 times more often before the age of two than bio parents.


167 – Religions and nations speak of brothers and sisters.


Accents indicate if you do or do not belong.  They are not easy to fake. They also change quickly, so if a group disperses, members can be identified as distinct after a generation. 


169 - So accents help us avoid those who would abuse our  natural cooperative nature.


170 – The higher the density of people, the faster their languages mutate.




What we use for good can also be used for evil (ie language).


Gossip may have evolved to trap the problem of freeloaders in the necessarily large groups.  Not to keep track of friends, but enemies to coerce them into conformity by guarding their reputation. 



173 - Much of our use of language deals with reputation management. 


174 - Only five percent of conversation is negative gossip.  The most common is who is doing what with whom.   He doesnÕt buy the freeloader explanation as to why language took off.


175 – How about self advertisement?


Both men and women talk of relationships an equal amount of time. Women talk about others social situations 2/3rds of the time.  And men talk of their own social situations 2/3rds of the time.   So we spend 65% talking of social situations.


Men and women share talking equally when alone.  Men talk more in groups.  This is because in groups its sales pitches, in couples it is building a relationship.  Big groups brainstorms.  Small groups decide.  In tribes, generosity is paid back round robin style.  Now not.  And, spouses have different groups of acquaintances. 


In communities, trust could be more or less assumed.  Now, trust has been replaced by asking for ID. The ability to rage is fed by anonymity. You yell at people on the road, but when you pull up next to them . . .


176 - Males talk more of work and academics when in mixed gender settings. This 5 – 15 percent rise may be advertising suitability. 


Women network men advertise. 


178 – People constantly monitor what is going on around them.


Women initiate contact in a bar.  They signal opposite by direct eye contact or a look and quick look away, a look back (confirmation) and a blush.  They use eyes to initiate relationships and contact.


179 - Non-harem controlling monkeys go out of the way to look disinterested when near the harem. They play with grass or stare nowhere.   Primate rivals take females from harems, but only when the female shows disinterest in her male.


Hunting may not be so much as getting food for the young as it is advertising strength.   It is like chivalric knights in medieval times. Youth male sports are advertising. 


181 - Such efforts are difficult to cheat in.


182 – Geoffrey Miller says perhaps making people laugh and enjoy your song is also PR.  Laughing releases opiates.  Women laugh more to men that to women AND they do so when men are talking, not themselves.  Men laugh less from females than from males.  If a man can make you laugh it shows fitness.  Female comics are less successful as they find it harder to make a mixed audience laugh.  


 Why the marry up factor women seldom marry down.  Men seldom marry up (hypergamy).  


Like Jane Austen, womenÕs personal ads often mention items related to status and achievement.  Men mention them when writing about themselves.


WomenÕs accents are more standard, menÕs more slang ridden.


For poor males, they cannot marry up, so having a good regional accent for social capital is important.


Being poor with the wrong accent is the kiss of death for a boy. 


Vocalizations do not release opiates.  Smiling and laughing, in particular, do.  


Laughing releases opiates.  This is not a replacement for their hypothesis but an addition.  Laughing likely comes from a submission symbol.  But, then it was hijacked to signal social status and mating interest.


More personal ads are words emphasizing relationship qualities for men.  Economics is of less drastic importance.  Peacocks with extra edges get more women.  Cut them off or paint them on and, . . .




194 – There are a limited number of people whose attention we can hold in a conversation: about 4.


Our brain has doubled in the previous ½ million years.  As in grooming, opiates create bonding. There is a direct correlation between sociability and frontal lobe proportion.  Perhaps humor is the modern bonder (smiling too). 


194 – Women talk less in mixed groups.  This has been interpreted as meaning men are dominant.  But, if talking is a display, the women are evaluating.  They are in charge and their talking would interrupt.  They speak equally to men in pairs, but less in bigger groups.  ThatÕs cause there is a choice.


197 – Victorian homes had lots of kids.  So they came up with Ôchildren should be seen and not heard.Ķ Perhaps their authoritative paternalism stems from this.


198 – He doubts teleconferences will be a hit because it is hard to get people to just listen to one speaker. 


199 – Alone and isolated, we have imaginary friends in soap operas.


201 – Those in Captain SmithÕs 1626 colony that had relatives lived longer.


202 – Not having community puts us at risk of exploitation by cults that promise belonging.


204 – Conversations around the photo copier are important.  People are not discrete in their on line conversations. Email likely wonÕt enlarge our real social networks.  Our brains are limited in what they can absorb.