40 | New Scientist | 6 March 2021
lives caused by covid-19 may be proving more
disruptive to some friendships than others.
I hadn’t anticipated quite how much we
would learn from scrutinising the mobile
phone bills of students. I was surprised to
find that everyone appears to have their own
unique social fingerprint, and intrigued to
discover that aspects of an individual’s social
style influence their friendship choices.
What was most unexpected, however, is the
durability of a person’s social fingerprint in
the face of change. It is as though exactly who
our friends are doesn’t really matter, as long
as we have friends. Of course, we opt for people
who are as congenial as possible, but, provided
these boxes are ticked, more or less anyone
will do. That may sound opportunistic or even
callous, but it makes sense. Friendship isn’t just
for fun; it has huge benefits for our mental and
physical well-being. In a changing world, our
approach to making and maintaining friends
needs to be both flexible and stable so that we
can optimise those benefits. ❚Robin Dunbar is at the University of
Oxford. This is an edited extract from
his new book Friends, published by
Little, Brown on 4 March 2021found that those who were early birds, or
larks, at the start of the study were still larks
18 months later, and the night owls at the start
were still owls at the end – despite the turnover
in their friends. That may not be so surprising,
but being a lark or an owl turns out to have big
implications for your social network.
Aledavood discovered this when she and her
colleagues analysed a similar data set of 1000
Danish university students. Being a much
larger group, it allowed them to look at the
relative frequencies of communication of larks
and owls in more detail. Some 20 per cent of
the students were committed larks, the same
proportion were committed owls and the rest
were neither one nor the other. Larks showed
no particular preference for having larks as
friends, but owls favoured associating with
owls, strongly reinforcing research showing
that what we most want in a friend is someone
just like us (see “Seven pillars of friendship”,
left). Owls also had larger social networks than
larks, at least in terms of the number of people
they phoned frequently – 35 rather than 28.
However, they spent less time on the phone
to each friend – 94 seconds compared with
112 seconds, on average, for larks – so their
networks weren’t as well integrated and
reinforced. Again, restrictions to our socialThe 30-minute rule
dictates how long
we are prepared to
travel to see friendsOur friends tend to be
surprisingly like us, and
there are certain personal
characteristics that predict how
close a friendship is likely to be:- You speak the same language
or, better still, dialect - You grew up in the same area
- You have the same educational
and career experiences - You pursue the same hobbies
and interests - You see eye to eye on moral,
religious and political matters - You share a sense of humour
- You have the same taste in music
Friends come and go for all
sorts of reasons, but if you want
to keep a friendship alive, you
must obey these six rules:- Stand up for friends
in their absence - Share important news
- Provide emotional support
when it is needed - Trust and confide in one another
- Volunteer to help when
a friend needs you - Try to make your friends happy
Six rules
for keeping
your pals
Seven
pillars of
friendship
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