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Wednesday 27 August 2008 (26 Sha`ban 1429)
Cows seem to know which way is north
Agencies
WASHINGTON: Somehow cattle seem to know how to find north and south, say
researchers who studied satellite photos of thousands of cows around the world.
Most cattle that were grazing or resting tended to align their bodies in a
north-south direction, a team of German and Czech researchers reported in
yesterday's issue of Proceedings of the National Academy of Sciences.
And the finding held true regardless of what continent the cattle were on,
according to the study led by Hynek Burda and Sabine Begall of the faculty of
biology at the University of Duisburg-Essen in Germany.
"The magnetic field of the Earth has to be considered as a factor," the
scientists said.
This challenges scientists to find out why and how these animals align to the
magnetic field, Begall said in an interview via e-mail. "Of course, the
question arises whether humans show also such a spontaneous behavior," she
said, adding, what "consequences does it have for their health."
"This is a surprising discovery," said Kenneth J. Lohmann of the biology
department at the University of North Carolina. "Nothing like this has been
observed before in cattle or in any large animal." However Lohmann, who was not
part of the research team, cautioned that "the study is based entirely on
correlations. To demonstrate conclusively that cattle have a magnetic sense,
some kind of experimental manipulation will eventually be needed."
Joseph L. Kirschvink of the California Institute of Technology said he wondered
if fences around the pastures could affect cattle orientation. Passive
alignment of animals to magnetic fields has been reported in honeybees and
termites, he noted. It requires some type of special sensory organ to detect
the magnetic field.
"If they have evidence suggesting that mammals are using magnetic fields to
orient their movements, this is very cool," said Mark A. Willis, an associate
professor of biomedical sciences at Case Western Reserve University in
Cleveland.
Willis, who was not part of the research team, added: "We have only in the last
few years begun to understand the mechanisms underlying magnetic field
orientation in birds and other smaller animals."
Indeed, it is small animals that led to this study, Begall explained. They were
researching the magnetic field effect on African mole-rats.
Now the researchers are moving on to study sheep, goats, horses, wild boar and
some further deer species, Begall added.
The current study said red and roe deer also were found to orient in a
north-south direction when grazing and resting, but unlike the worldwide cattle
study, the deer portion was limited to the Czech Republic.
Herdsmen and hunters have long known that cattle and sheep tend to face the
same direction when grazing, but had believed they were simply positioning
themselves according to prevailing winds or the sun's rays.
Although not seen before in large mammals, birds, turtles and salmon are known
to use the Earth's magnetic field to guide their migrations, while rodents and
one bat species have been found to possess an internal magnetic compass.
The researchers noted that humans and even whales are suspected of having an
innate magnetic compass.
Some studies suggest humans who sleep in an east-west position have far shorter
rapid eye movement or REM sleep cycles, in which dreams occur, compared with
north-south sleepers who got more REM sleep.
"Our results call for an in-depth study of this phenomenon and challenge
neuroscientists, biochemists and physicists to study the proximate mechanisms
and biological significance of magnetic alignment," Begall and colleagues wrote
