The New
Scientist February 9,
2011
http://www.newscientist.com/article/dn20109-zoologger-
the-sharpest-mind-in-the-farmyard.html
Sheep
among
The
sharpest mind in the
farmyard
By Michael
Marshall
When we
look for examples of intelligent
animals, certain species
always leap
to mind. Ourselves of course, and
our close relatives the
chimpanzees
and other primates. Perhaps the
cunning corvids - crows
and scrub
jays - with their prodigious
memories and talent for
deception.
Dolphins and whales are pretty
bright. Many would even
agree that
there is a sort of intelligence
governing the behaviour of
social
insects like ants.
But sheep?
Sheep are just thick.
Except that
they aren't. Over the past few
decades, evidence has
quietly
built up that sheep are anything
but stupid. It now turns out
that the
humble domestic sheep can pass a
psychological test that
monkeys
struggle with, and which is so
sensitive it is used to look
for
neurological decline in human
patients.
Woolly
thinkers
Laura
Avanzo and Jennifer Morton of the
University of Cambridge were
interested
in a new kind of genetically
modified sheep. These animals
carry a
defective gene that in humans
causes Huntington's disease, an
inherited
disorder that leads to nerve
damage and dementia. The hope
is that the
Huntington's sheep could be a
testing ground for possible
treatments.
For that to
work, they reasoned, researchers
will have to be able to
track
changes in the cognitive
abilities of the Huntington's
sheep.
So they
decided to find out whether
normal sheep could pass some of
the
challenging tests given to people
with Huntington's. If the sheep
passed,
that would mean that the
Huntington's sheep could be seen
losing the
ability as their disease
progressed - and maybe regaining
it if any
treatments worked.
So Avanzo
and Morton put seven female sheep
through a series of
increasingly
tricky challenges. In one test
the sheep walked into a
pen that
contained two buckets, one blue
and the other yellow, with
some food
in the blue one. Over the course
of a few trials they
learned
what was going on and always went
to the blue bucket.
When the
researchers put the food in the
yellow bucket instead, the
sheep
changed their behaviour
accordingly. They also mastered a
subtler
game in which the food was still
in one of the buckets but
the clue to
its location was the colour of a
cone placed nearby, not
the colour
of the bucket itself.
Extra
dimensions
Next Avanzo
and Morton stepped up the
intellectual pressure, trying
the sheep
on intra-dimensional and
extra-dimensional set-shifting.
These
tested the animals' ability to
shift their attention, something
that
requires a high level of mental
control.
In
intra-dimensional set-shifting,
the sheep still had to choose a
bucket
based on colour, but the set of
colours was different: instead
of blue and
yellow, the choice was purple and
green. Humans find this
pretty
easy. Extra-dimensional shifting
is harder, as the sheep had
to ignore
the colour of the objects and
instead focus on their
shapes.
In a
touching piece of scientific
understatement, Avanzo and Morton
note that
their decision to do these tests
"was driven more by
curiosity
than expectation". Humans and
other primates can do
set-shifting,
but other large animals struggle
with it - although
researchers
have persuaded mice and rats to
do it. The task relies on
the
prefrontal cortex, a part of the
brain that is much bigger in
humans than
other animals.
Impressively,
the sheep passed the tests,
learning to attend either
to
different pairs of colours or to
the objects' shapes as necessary.
As well as
being good news for the study of
Huntington's disease,
it's one
more step towards rehabilitating
sheep's reputation.
Top of the
flock
It really
is about time we stopped making
fun of sheep. They can not
only
recognise each other's faces,
especially sheep they are
socially
close to -
they can remember significant
others for at least two
years. They
can also discriminate breeds,
preferring to look at their
own.
What's
more, there is evidence that they
can group plants by family
and
memorise the correct route
through a maze. They have
sophisticated
social lives too: rams become
long-term buddies and
stick up
for each other in
fights.
There are
even claims that sheep in the UK
have learned to cross
cattle
grids by rolling across them, but
further research may be
needed on
that point.
Journal
reference: PLoS One, DOI:
10.1371/journal.pone.0015752
If only
these scientists would decide NOT
to do SUCH NASTY THINGS to
them (i.e.,
in this case, 'engineering' them
to suffer from
Huntingdon's
disease) ... and, if the sheep
farmers would decide to
stop doing
even worse...
