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.
