http://www.uboeschenstein.ch/sal/dunbar.html

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 species.

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 over time.
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 limits.
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.

Cementing relationships
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 cent.
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 maintain cohesion.

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 mauling.

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 sapiens.
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 College London.

Citazione:
Da quando "new theory" significa fatto assodato?
Da dove ti viene l'arroganza con cui sembri affermare "le cose sono andate così e se non sei d'accordo sei un cretino"?

Suggerisco la lettura di un testo di antropologia se l'argomento dello sviluppo del linguaggio complesso ti interessa davvero. Anche un testo divulgativo (come quelli di Jared Diamond) va bene e contiene mille volte più informazioni di tutti i superquack mai trasmessi.

Lascia perdere piero angela. I suoi documentari sono un'ammasso di piccole curiosità scientifiche (nei documentari si privilegia una notizia buffa o sconcertante piuttosto che una notizia meno accattivante ma più importante, perchè si devono rivolgere al più ampio pubblico possibile. Risultato? Nei documentari trovi solo i fatti essenziali e qualche fatterello o teoria curiosa o divertente. Niente di più. Inutile dire che non è proprio il modo ideale di farsi una cultura su di un argomento).

Chi ha detto che è un fatto assodato? E chi ha detto che chi non è d'accordo è un deficiente?

Tale metodo di argomentare lo lascio volentieri al webmaster. È lui che ha definito una mostruosa cazzata una cosa che non si è sforzato di comprendere neanche nei minimi termini.

Quello di Piero Angela, se non si fosse ben capito, non è altro che un programma divulgativo, non è scienza. Vengono presentate, a volte in modo un po' troppo adattato all'utenza televisiva, ricerche scientifiche e ipotesi di vari ricercatori. Quelle sono le fonti da debunkare, se proprio vogliamo, e non fare finta che le ha dette Piero Angela proprio in quei termini.

Jared Diamond sostiene che l'Europa ha conquistato militarmente gli altri continenti (Africa e Americhe), perché il continente euroasiatico è orizzontale, e gli altri sono verticali. Ecco un esempio di una cosa che sembra che una gran cazzata, se non la si approfondisce.

Citazione:
Infatti: è lo Stato (non europeo) USA che ha le basi militare sul suolo europeo, e non viceversa.
Immagino che tale mr Diamond si riferisse ad epoche meno recenti di quelle dal secolo scorso ad oggi... Ma anche applicata a periodi precedenti andrebbe approfondito il discorso (Gengis Khan ad esempio costruì uno dei più estesi imperi rimanendo sostanzialmente in Eurasia).
Ai tempi d'oggi, la teoria del verticale e orizzontale non mi sembra un criterio né utile né applicabilie. anche perchè la presenza cinese in Africa è tutt'altro che trascurabile... e le cause sono quelle più semplici da chiarire: la lotta per l'accesso alle fonti energetiche (carbone, gas, petrolio).

vedi com'è che una cosa sembra poi una idiozia: semplificando semplificando... non si dice più niente di ragionevole.

Quello di Piero Angela, se non si fosse ben capito, non è altro che un programma divulgativo, non è scienza. Vengono presentate, a volte in modo un po' troppo adattato all'utenza televisiva, ricerche scientifiche e ipotesi di vari ricercatori. Quelle sono le fonti da debunkare, se proprio vogliamo

Vuoi? Puoi farlo tu!

Citazione:

Ma è proprio detta in quel modo, estremamente ridotta all'osso, che magari attira più attenzione e spinge a informarsi di più.

Ovvio comunque che Diamond si riferiva alle epoche passate (la popolazione Usa è fatta di europei, non di nativi americani).

Citazione:
And that has, of course, nothing to do with editorial/political choiches, has not?

Citazione:
Has anyone noticed that a similar percentage of working time is the equivalent of the price paid by the individuals to satisfy the feeding habits of the bureaucratic machine?

Citazione:
A respectable suggestion.

Citazione:
No, that's not gossip, it's exchanging of vital information: if you consider it gossip you'll therefore are labelling as "gossip" all major financial newspapers.

Citazione:
Well, it could but actually it doesn't, really.

Also, leaving alone the newspapers that could have other reasons for publishing rubbish (i.e. rubbish is cheap), it is not a fact that gossip has an overwhelming proportion of human conversation: maybe in small minded people conversation or in small talk to break embarassment, but definitely not in the conversation of people that are actually able to talk about a definite subject of interest, by the way.

It is also remarkable that the very people still living in small groups of hunter gatherers (allegedly given by the author of the study as the groups in which is the gossiping factor did develop uman language) is pretty much free from gossip and very inclined to silence!

Citazione:
It doesn't: it mixes carefully well-known facts to wishful thinking without not even remotely explaining any of the various facts it claims to explain.

che81
Quello di Piero Angela, se non si fosse ben capito, non è altro che un programma divulgativo, non è scienza.

Un programma che parla di scienza ma che fa divulgazione e non scienza si chiama "propaganda".

Ottima risposta, Pike (senza ironia).

Solo una cosa:

Citazione:

Questa certezza da dove ti viene? Esperienza personale o qualche idilliaco documentario sui popoli primitivi (magari presentato da Piero Angela)?

Citazione:
Esperienza personale e anche vari esami di Antropologia Culturale con un pacco di testi da studiare, e da studiare davvero, essendo il mio relatore Matthey (un genio esigente).

Piero Angela invece non l'ho piu' visto dal 1970, quando ho cominciato il liceo. Fino a qualche giorno fa quando l'ho visto in versione ormai mummificata (cioe' esattamente uguale, solo con polvere e ragnatele) grazie al filmato di Mazzucco.
Credo che fosse anche uno dei redattori dell'infame speciale di divulgazione scientifica de "La Stampa" a nome "Tuttoscienze", amichevolmente chiamato dagli studenti torinesi il "Tuttoniente", tanto per sottolinearne lo spessore: beh, penso di essere stato io il tale che ha concepito il nomignolo.

Che81, senti, ragioniamo insieme, visto che mi sei anche simpatico (sembri intelligente e anche piuttosto istruito - non mi era mai capitato di incontrare un debunker che conoscesse Jared Diamond, tanto per dirne una. Potremmo pure essere amici, se le nostre casate non fossero nemiche).

Ammettiamo pure che Mazzucco abbia detto una cazzata.
Ammettiamo che per una volta si sia lasciato trascinare dai peggiori istinti che condividiamo con i pieri angela di questo mondo e che abbia commesso l'errore che, guarda caso, fanno tante persone riguardo molte cose (di primo acchito mi sembra impossibile che sia successa una certa cosa, quindi sicuramente è una cazzata). Ammettiamo che si sia macchiato di una tale colpa.
Ok, abbiamo scoperto che Mazzucco è un essere umano. Ogni tanto, su mille frasi ne dice una non proprio esatta, vuoi per la fretta, vuoi per qual che altro motivo.
Quindi?
Non mi pare correttissimo concentrarsi come fai tu su una questione satellite e secondaria al discorso principale (ossia le immani e gravissime stronzate dette a superquark). Non ha alcun senso.
A meno che tu non voglia cambiare discorso.

La chiudiamo qui?

(non aspettarti una risposta perchè vado via e starò lontano dal pc per 7-8 giorni)

Citazione:

Ok. Un paio di esami però li ho fatti anch'io, ma evidentemente gli antropologi non sono tutti d'accordo (diverse scuole, suppongo).

Fra gli Yanomami, in Amazzonia, il gossip nella sua accezione più malevola, per cui hanno una parola specifica (notha wei) è una delle più frequenti cause di rottura fra gruppi e di tensione.

Fonte

Ottima risposta, Pike (senza ironia).

Ma come Pike, e non salti di gioia?

che cosa è il gossip allora?
perché la questione generale è che il linguaggio è una forma di comunicazione la cui funzione principale è relazionale, al di là delle informazioni vitali veicolate.
se prima di parlare ci spulciavamo per socializzare, con il linguaggio abbiamo scoperto che lo possiamo fare meglio.
praticamente è il mezzo più funzionale per raggiungere il fine di creare coesione e un gruppo compatto ha più probabilità di sopravvivenza.
è inaccettabile?

Ma come Pike, e non salti di gioia?

Dovrebbe, quant'è vero che mi metto a piangere di disperazione quando leggo i tuoi commenti sarcastici.

Citazione:Non lo so il problema è che la parola crea anche incomprensione... ad esempio tu dici che crea coesione...
Qualcun'altro invece...
Citazione:
Che si fa?

Citazione:

SULLA PAROLA di Gibran Kalhil Gibran

E allora uno studioso disse: Spiegaci la Parola.

E lui rispose dicendo:

Voi parlate quando avete perduto la pace con i vostri pensieri; E quando non potete più sopportare la solitudine del cuore voi vivete sulle labbra, e il suono vi è di svago e passatempo. E molte delle vostre parole quasi uccidono il pensiero, Poiché il pensiero è un uccello leggero che in una gabbia di parole può spiegare le ali, ma non prendere il volo. Tra voi vi sono quelli che cercano uomini loquaci per timore di restare soli. Il silenzio della solitudine mette a nudo il loro essere, ed essi vorrebbero fuggirlo. E vi sono quelli che, senza consapevolezza o prudenza parlano di verità che non comprendono. E quelli invece che hanno dentro di sé la verità, ma non la esprimono in parole. Nel loro petto lo spirito dimora in armonico silenzio. Quando per strada o sulla piazza del mercato incontrate un amico, lasciate che lo spirito vi muova le labbra e vi guidi la lingua. Lasciate che la voce della vostra voce parli all'orecchio del suo orecchio; Poiché custodirà nell'anima la verità del vostro cuore come si ricorda il sapore del vino. Quando il colore è dimenticato e la coppa è perduta.

Lonewolf:

Citazione:

E' vero. Sembra esserci contraddizione, ma è facilmente superabile. È proprio il dividersi in gruppi ostili fra loro che è uno dei maggiori fattori di coesione.

Citazione: dopo di che... un bel salto alla neuro non ce lo toglie nessuno...

Citazione:

Anche gli inglesi e si chiama bitching e non ha molto a che fare con gossiping esempio della seconda cosa:

"Hai visto che canna che aveva Arturo, quello e' un fanatico degli accessori" "Secondo me non prende un cazzo come al solito" "Ma sai dove l'abbia comprata" "In quel negozio costoso" "Arturo pero' l'ultima volta non ha pescato cosi' male" "Culo, niente a che vedere con la canna nuova"

Esempio della prima:

"Ciao Enrico, come sta tua moglie?" "Bene grazie" "Sta molto bene con quella sua minigonna vertiginosa, l'ho vista l'altro giorno col suo ex, Rodolfo" "L'ho vista anch'io Enrico, ma dovresti dirgli di non farsi beccare cosi' nel parco..." "Cosi' come?" "Mah, gia' circolano quelle voci che tuo figlio non sia in realta' tuo perche' sei impotente" "Voci???? DA CHI???" "Da quell'imfame del macellaio che si scopava anche tua madre, senza offesa" " Si Enrico, l'ho sentito anch'io dirlo nel negozio pieno zeppo".

Chiaramente la seconda cosa ha un'accezione negativa perche' provoca frizioni in una comunita' che sarebbe meglio che non ne avessero e percio' ha un vocabolo particolare di connotazione negativa, ma potrebbe essere invece uno scambio di informazioni utili fuori dai denti. Di solito queste cose non succedono pero' quando c'e' un crisi, ma solo quando la popolazione e' in aumento e non e' cosi' male se qualcuno prende il largo.

A me succede al lavoro in tutti quei giorni in cui non c'e' un po' di violenza per cui la gente si chiede: che cazzo li paghiamo a fare 'sti stronzi in divisa? Ma appena c'e' un po' di casino, tutti culo e camicia. No notha wei.

Niente a che vedere col gossip, anyway.

Chi ha detto che è un fatto assodato? E chi ha detto che chi non è d'accordo è un deficiente?

Nessuno. Ma quando vedo l'eroica faccia del Che cerco sempre di essere d'accordo, laonde non finire in qualche campo di morte o in una fossa comune.

Infatti. Prega che non passi Audisio da queste parti, o sono ***** amari