Yahoo – AFP,
Richard Ingham, 27 Aug 2014
A sheepdog
herds a flock in Lowther, northwest England, on September 13,
2009 (AFP
Photo/Paul Ellis)
|
Paris (AFP)
- There is the riddle of the Bermuda Triangle. The unresolved identity of Jack
the Ripper. The enigma of how the Universe developed beyond a quark-gluon soup
following the Big Bang.
And then
there is the Sheepdog Mystery.
A puzzle
that has niggled mathematical minds for years, the Mystery is this: how does a
single dog get so many selfish sheep to move so efficiently in the same
direction?
The answer,
revealed on Tuesday in a journal published by Britain's prestigious Royal
Society, is that sheepdogs cleverly follow a simple rulebook.
Researchers
fitted highly accurate GPS tracking devices into backpacks that were then
placed on a trained Australian Kelpie sheepdog and on a flock of 46 female
merino sheep in a five-hectare (12-acre) field.
They then
used the GPS data to build a computer model of what prompted the dog to move,
and how it responded.
Sheep
cohesiveness is the big clue.
The dog's
first rule is to bind the sheep together by weaving around side-to-side at their
backs, and once this has been achieved, it drives the group forward.
"It
basically sees white, fluffy things in front of it," said Andrew King of
Swansea University in Wales.
"If
the dog sees gaps between the sheep, or the gaps are getting bigger, the dog
needs to bring them together."
Daniel
Stroembom of Uppsala University in Sweden explained: "At every step in the
model, the dog decides if the herd is cohesive enough or not.
"If
not cohesive, it will make it cohesive, but if it's already cohesive, the dog
will push the herd towards the target."
Single
sheep dogs can successfully herd flocks of 80 or more sheep in their everyday
work and in competitive herding trials.
But the
model suggests that, in theory, a dog could herd more than 100 by following the
two simple rules.
In
contrast, other attempts at resolving the Sheepdog Mystery are more
pessimistic. They say that 50 sheep would be the limit -- beyond this, another
dog (or a human) would be needed to close up the gaps.
The study,
published in the Journal of the Royal Society Interface, comes with an
intimidatingly geeky headline: "Solving the Shepherding Problem:
Heuristics for Herding Autonomous, Interacting Agents."
But the
work goes beyond scientific curiosity, said the authors.
"There
are numerous applications for this knowledge, such as crowd control, cleaning
up the environment, herding of livestock, keeping animals away from sensitive
areas and collective or guiding groups of exploring robots," said King.
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