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This is an individual's social network
the individual is in the middle, surrounded by
his contacts, and their contacts
interconnected amongst themselves.
You'll note it's complex.
It's hard to read, no?
This is relevant because
somehow our ancestors' social network
was complex too
(I'm referring to our primate ancestors)
but in evolutionary terms it favored
the development of larger brains.
Because this individual had to keep track of
so many connections between other individuals
in order to belong and remain
in societies or groups of societies
the brain started to favor in evolutionary terms
the growth of the brain to allow us to track
social connections and make use of these systems.
In primates in general there is a strong relationship
between the size of the group
and the relative size of the neocortex.
In charge of conscious thinking,
the neocortex is this part here,
it's the last phase in the brain's evolution.
The brain's capacity for keeping track of the
complex and changing social context
is limited by the size of
the neocortex, that is:
the larger our head
(as a species, not as individuals)
the larger our brain has gotten
the more we've developed
the capacity to keep
contact within these networks.
What is interesting is that there is a number
known as "Dunbar's number".
One hundred and fifty is
the limit of quality relationships
that we can keep with high levels of complexity.
Many of you may recall when we were six years old
we had all the best friends in the world
and life changes, and perhaps you
don't notice but you
let go of quality relationships
so you can generate
other quality relationships.
This is because our brain has this limit.
Why 150? Because 150 is
the individuals around us
but for me to have a quality relationship
with Jorge, I have to be able to ask him:
"How is your brother Gustavo?"
"How is your dad, Jorge?"
"How is your dad's farm?"
and you have to be able to keep track of a lot of
connections that are not to
the direct individual
and that gets complicated fast
and saturates our neocortex.
It's literally as this drawing shows
this is more or less what happens to us:
number 51 comes in
and number 151 at the end of the list
gets pushed out from our consciousness
of quality relationships.
The size of our groups between
intimacy and community tends to increase
in factors of three.
In general, we have five really close friends
people we see every day
with whom we share.
The we have 15 that we see about
every two weeks or so, we go to a bar
or to the beach... we're friends.
It grows from there
but it tends to do so in factors of three
up until 150, which is the golden number.
Then comes 500 and 1,500
where we have a feeling of belonging to a group
but you can't really track
exactly where the individual is at
in that group, but you feel like you belong
in information architects
then me and information architects
are a group of around 500 in my mind
I feel like I belong in groups of up to 500.
When you get to 1,500, you have a community,
and those are the scales.
This has been around forever, it's part of our evolution.
It's interesting,
in societies of hunter-gatherers,
a camp had between 30 and 50
individuals.
The clan, which was
the biggest independent unit
had 150 individuals.
The tribe had between 500 and 2,500.
This also happens in businesses.
According to business theory,150
is the limit of co-workers
that can work efficiently without a formal hierarchy.
For example, any of you who work with
programmers in different parts of the world know that
you can be ad-hoc and
and loose, there is no formal structure there
no one to enforce rules or laws
but after 150, it starts to disintegrate
factions and cliques start to emerge
this guy over here, and "I'm not gonna do that", and
"Why should I...?", and then you need to
create a control hierarchy
because the network starts to dissolve
peer pressure.
In the army, the company
is the smallest independent combat unit.
It has on average 150 soldiers.
In academia,
150 is the amount of researchers that
an individual can follow.
More than this, and it starts to fragment
into different disciplines.