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Friends - the old fashioned kind -

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How many friends can someone actually have and interact with? Robin Dunbar suggests people can only
have four or five close personal friends, with about 150 contacts being a limit in one's social
world. Maintaining people in a network requires personal contact, otherwise they slide away. Robin
Dunbar says doing things together is the key, something which can't be replicated online.
Neuroimaging studies show a relationship between the size of our frontal lobes and the number of
close friends we have. In evolutionary history, we departed from other apes when we developed the
capacity to live in a virtual mental world. Now other apes are under threat as their habitats are
being destroyed. As climate warms, they'll look to move, but there won't be forests for them to
move into.

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Robyn Williams: So what happens when you move around like that and have got bunches of friends in
different places, or even just on the ends of phones or computers? Are they real friends or just
virtual ones? And can there be a direct link between friends and the size of your brain? Robin
Dunbar is convinced that there is.

Robin Dunbar: Well, the short answer is that mobile technology and electronic communications,
things like Facebook, don't really affect the number of people you can count as real friends. You
can sign up 10,000 people on your Facebook page, quite a lot of people do, but the real issue is
how many of those do they really actually know as individuals, and interact with in that
environment. And if you look at that, it's very much a smaller number. There tends to be this inner
circle core of about perhaps five people, and this sort of limiting value of about 150, which they
would count as real personal acquaintances in some form. And then beyond that it's just numbers,

Robyn Williams: Just noise.

Robin Dunbar: Just noise. But it's acquired this kind of mystique of, 'well, I've got 400 friends,
how many have you got?' 'Well, 600.' It's a sort of game, in a way. And that said, that was fun
while that was happening and people were building up these sort of numbers, but there's been a lot
of discussion on Facebook about whether in fact it's just getting out of hand. I mean, people just
can't cope with it. So Facebook themselves have started to introduce these filtering processes,
because you really didn't want your girlfriend's mother seeing what you'd been up to.

Robyn Williams: Is this just a passing experiment, or are we in for, given the huge populations in
big cities where most of us live these days in modern times, going to have to deal with a different
kind of virtual friendship that's going to be quite different from those that we're prepared for as
human beings and biological species?

Robin Dunbar: There's no question that all these kinds of things, even chunky stuff like email, has
been a big boon in maintaining your social world, as it were. If you think back to the context of,
say, the 1850s in Europe, farming communities, everyone knew everybody else. They were of that kind
of order. Villages typically of about 150 people or so in rural environments. That's what you see
in traditional societies, particularly hunter-gatherer societies. Everybody knows everybody else.
Now, if you think what happened, say, end of the 19th century, Uncle Jim got up and went off to
Australia, panning for gold and what have you, and that was the last the family ever heard of him,
because the process of keeping up contact was just so laborious, even with the penny post, as they

Those sort of migrants then tended to disappear off the family radar completely, and vice versa, so
the contact was broken. What things like Facebook and email have allowed us to do is to maintain
those links over distance so that they don't drop off. Because it's maintain people in
your network, you have to see them regularly, you have to do stuff with them, really. And if you
don't they kind of slide gradually and gracefully...some people are more resistant, some slide more
quickly...out of your circle of knowledge. And this at least allows them to slow down the rate of
loss, as it were.

Robyn Williams: There is some theory that...and of course Susan Greenfield has espoused this...that
having the technology is going to diminish the number of friends, because you're living in this
isolated world where you don't actually meet people much any more, especially young people. Are you
worried about that?

Robin Dunbar: I would be a bit worried, I think, too, because I do think at the end of day the
quality of your relationships actually does depend on doing stuff together. You can't create
relationships in a virtual environment, because there is something very sort of visceral about
going off and getting drunk together, or whatever it is you do, you know, white-water rafting or
watching the tennis...whatever you, it's doing stuff with people, having dinner with them and what
have you. There is something about that face-to-face experience which is absolutely irreplaceable.
Now the electronic communications can allow you to keep that going once it's established over time
and space in a way which would otherwise be difficult to do. But it is not an environment for
creating friendship. So if your whole life is locked into this small electronic world, I suspect
you are heading for a-sociality.

Robyn Williams: Now you've looked at animals and the size of their brains, and from parts of the
brains managed to predict the size of the social group. We had arguments once about orang-utans,
but are you looking at ways in which people themselves can be distinguished according to brain size
and so on?

Robin Dunbar: We have actually looked at this quite recently. And what had set us off down this
route is...I mean, you have to remember that this figure of 150 is your sort of outer limit. It
includes a lot of people you don't see very often. The core to your relationships are really the
inner circles that sit within that of about five and 15 people. And we were struck by a quite
serendipitous set of results we had which showed that the size of that group, that in a core of 15,
correlated with your ability to handle mentalising problems. By 'mentalising' I mean the ability to
understand how other people are thinking, what's going on in their minds. And the scale on which
you could do that correlated with their social network size.

So we sort of made the obvious leap and said, well, actually if these mentalising issues are
involved, then that's hardware stuff. Brains do that. So maybe there's a kind of three-way
correlation here between the sort of size or activity of those bits of the brain that are deeply
embroiled in creating those mentalising capacities, secondly, and thirdly your social network size.
So there's a three-way correlation here. So we've just finished a whole series of studies,
neuro-imaging studies, in which we've put people through scanners, measured the size of bits of
their brain, made them do these tests, made them tell us how many friends they've got...and sure
enough, you've got a very nice relationship. The size of particularly the frontal part of your
brain up here tells us how many friends you've got.

Robyn Williams: What's the relationship; lots of friends for a big frontal, or vice versa?

Robin Dunbar: It's lots of friends for a big frontal. And I think it's simply because it is a
computational problem. Essentially you're trying to keep, let's say, half a dozen minds on the go,
your really close friends that you have. And that's actually very hard work. You've got to be
constantly factoring in how they see the world and what they would like to do, and taking their
needs into account with how you want to organise and schedule your life. And doing that is just
hard computation. It's a computer problem, so the size of your computer dictates how many friends
you can have.

Robyn Williams: And the same goes for women as for men?

Robin Dunbar: Yes, it does indeed. I hesitate to say this, but the ladies have slightly bigger
circles of friends than men do, and as a result they're slightly better at these mentalising tasks,
and we're not going down the road on how big their brains are.

Robyn Williams: Darwin famously cast nasturtiums on the size of women's brains, but what do you
think the point of this kind of study might be? What will it tell you about human relationships
that you didn't know before?

Robin Dunbar: At one level we're interested in just how we got to be the way we are. Why is it that
we have evolved these incredibly expensive capacities? I mean, your brain is hugely expensive
compared with the rest of your body. So from an evolutionary point of view that's a serious
challenge to evolutionary processes. Something really good has to come out of it, otherwise
evolution won't produce it.

So it's just trying to understand why it is that humans aren't just great apes, you know, we belong
to the great ape family. But some point in the course of the last, let's say, three million years
since the Australopithecine period, something gave us a big kick in evolutionary terms, which is
built round this's actually to live in this virtual mental world, that's what it's
all about, by having a big brain. You know, why did that happen, why were our ancestors, if you
like to put it this way, prepared to pay the costs of doing that? It must have been important. So
that then also tells us something about the natural structures of human social groups.

And this has implications for...things like politics really. I mean, how do you structure your
communities? We live in these huge nation states, these massive conurbations, like Sydney and
Melbourne and so on. How do you get people to pull together? They end up fighting each other or
you've got these, like we have here, these sort of utterly dysfunctional estates where people are
at each other's throats all the time...

Robyn Williams: Warehoused almost.

Robin Dunbar: Warehoused, exactly. That's a consequence of economics and what have you running away
with us and just creating this as sort of unavoidable mechanisms for just providing housing for
people to run industries and all that kind of thing. It's a historical thing. But now that we've
got it, we've got big problems. How do you make people pull together more in the community? What is
it that actually drives human relationships and human communities...what are the natural sizes of
communities? There are implications for schools, you know, if your natural human grouping is 150,
should that be the limit on the size of schools, for example, and never have a school bigger than
that if you want to have that sense of belonging and community in the place.

Robyn Williams: Of course, having a brain like we do, we can understand the way groups of thousands
if not millions can work, and we can imagine that and we can tell stories about it and cope with
it, whereas for smaller brains it would just be far too much.

Robin Dunbar: Oh no, that's certainly true. We have only got into this mess because we've got a big
brain, and that big brain has allowed us to kind of use boot-strapping ways of making super-large
communities work. So we can attach labels to people. We can put badges on them and holsters on
their hips and call them policemen. And then when you see somebody with those badges, how to behave
towards them. You've got a sort of a modus don't need to know who they are in any
detail. So that allows these sorts of large political units, if you like, to work reasonably well.
But still they are constantly being undermined by the fact that people in the end don't feel any
grand sense of obligation towards everybody else.

In our minds we're still living back in these small hunter-gatherer communities of about 150
people, and those are the people we feel allegiance to. Well now, how do you make everybody in the
whole of Australia feel deep allegiance...Australians always feel allegiance to each other, but big
countries tend to have this sort of fractionation problem. How do you make everybody have this
sense of belonging to some grand project, which is the nation you belong to, or the world as a
whole? We are constantly torn between the sort of selfish interests of the individual who wants a
very small-scale world and the fact that actually if we don't sort it out on the big scale, we're
in deep, deep trouble very soon.

Robyn Williams: Finally let me ask you about our near relatives who are quite different, and with a
changing world what are the prospects for our ape cousins? Are they going to make it?

Robin Dunbar: I'm afraid our ape cousins are not in good shape. They haven't been in good shape for
a very long time. You have to remember that the ape family, collectively, with the sole exception
of our lineage, has been in terminal decline for about the last six or seven million years. What we
see now as the four species of great ape that we have, is really the rump of what there were ten
million years ago. The real problems that the great apes are facing now is actually going to be
climate warming. What people worry about in the conservation world at the moment is deforestation
and meat-eating, killing animals off for meat, and they are what are causing ape populations to
decline all over Africa and South Asia. But in the end even if we solve those problems, what they
have looming over their heads is climate warming.

And for the chimpanzees, for example, we only have chimpanzees with us today, and they're probably
the most widely distributed of the great apes, because they're able to live in these kind of
fission-fusion social systems, where not everyone lives together. They come and go and they live in
a kind of dispersed society. But they are actually at the limit that they can manage that. If it
gets warmer, they simply aren't going to be able to disperse any more than they are, and they're
just going to drop out at the bottom at some point, say in the next 50 to 100 years.

Robyn Williams: You mean the forests will go that they can live in?

Robin Dunbar: The forests will be there, they just won't be able to cope with the impact of higher

Robyn Williams: I see, they're that sensitive to it.

Robin Dunbar: Yes. It's a real problem. And the problem for them is the amount of travel time they
have to do in order to get enough food. They have two problems; one is that apes, in contrast to
monkeys, really cannot cope with unripe fruits. So they have to invest a lot of their time in
feeding and as a result they have to travel a lot to find trees with enough ripe fruits for them.
Monkeys can eat the stuff when it's unripe, and it's no problem for them. Well, that really causes
the great apes, or at least the African great apes in particular, a huge problem in terms of the
demand for moving time during the day.

So as long as they live in sort of groups approaching two or three individuals, they can keep that
under control. But if they try to live in the size of communities they actually have, which is
about 50 animals, their moving time requirement just goes through the roof. They'd have to spend
all day moving and not doing anything else. So they're really trapped by their design, as it were,
and you can't change that kind of thing, their biological design, you can't change that kind of
thing that fast.

Robyn Williams: So we'll have to say goodbye to them.

Robin Dunbar: I think if you want to see them, book your ticket now.

Robyn Williams: A last chance to see biodiversity again. Robin Dunbar is professor of evolutionary
anthropology at Oxford, studying us in groups, and apes in groups...while they last.


Robin Dunbar

Professor of Evolutionary Anthropology University of Oxford Oxford UK


Robyn Williams


David Fisher

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