4.6 Critical thinking and science 167
primates, which are already understood to be
at the smarter end of the scale of animal
intelligence. You may want to qualify your
answer by saying that the graph tells us
something about smartness and bonded
groups.
Another point you might make is that the
graph tells us only about the correlation
between group size and brain size (or neocortex
ratio to be precise.) Does this permit us to make
the further claim that animals which form
bigger groups are ‘smarter’? To put it another
way, is there an assumption that brain size
equals smartness? The problem is that we need
a definition of smartness that connects it with
brain size. Without that it would be jumping
to a conclusion to say that group size – even
bonded-group size – indicated intelligence.
Another point still that you could raise is
that although there is a general match
between group size and brain size, there are
some exceptions. As we observed earlier, the
three ape species apparently form smaller
groups than many monkeys with similar-sized
or even smaller brains. If apes are more
intelligent because their brains are larger, why
would they live in smaller groups? This at
least requires some explanation if we want to
make the connection between group size and
smartness.
So a good answer to a question like this is
more than simply yes or no. You may be
satisfied that the graph does tell us something
about the smartness of a species, but you
must be able to say why you reached this
judgement. You should also be prepared to
qualify your answer by adding reservations, or
acknowledging the assumptions that have to
be made, or further questions that have to be
answered. Likewise, if you decided that the
graph does not tell us anything about
smartness, you would need to give your
reasons, and to acknowledge what it does tell
us as well as what it does not.values is large, as it is in this case. Group sizes
start at about 3 and rise to around 150 (in
humans). With an ordinary scale the graph
would either have to be very tall, or the dots
would be packed so tightly together that they
would be difficult to tell apart.
Each dot or circle on the graph represents
one species. The pattern of the dots suggests
that the primates with bigger brains tend to
form larger groups. Most of the monkeys with
a brain size rated at less than 2 live in group
sizes smaller than 10. Those with brain sizes
between 2 and 3 form much larger groups:
anywhere between 10 and 100. With apes, too,
there is a correlation between brain and group
size, although their groups are slightly smaller
in relation to their brain size. Only humans
form groups of more than 100.
So, to get back to the main question, the
graph does show a general correlation between
brain size (as it is defined) and group size, both
in monkeys and in apes. Humans top the table
on both counts, and humans are very smart –
or so we tell ourselves. Therefore it could be
argued that group size is an indicator of
smartness: the larger the group, the greater
the intelligence. The author even offers an
explanation for this in Doc A. Social networks,
he says, are ‘costly’, and only the smartest
species could manage them. (By ‘cost’ he
probably means the time and effort that they
take up, which could be spent eating or
hunting instead.)
But there is a proviso. Yes, the data on group
size and brain size does tell us something
about the smartness or intelligence of a
species, but only if the groups in question are
‘bonded’ or ‘social’ groups. We know from the
earlier discussion that big herds, shoals and so
on don’t count as social groups. If they did
then there would be some animals (e.g. some
fish) that have very small brains but gather
together in groups of thousands. The graph on
its own, therefore, is selective. It relates only to