In A Nutshell
Since humans first began farming cattle thousands of years ago, we’ve always assumed that our bovine friends graze in a random way. But in 2008, German scientists took to Google Earth to study cattle herds and uncovered some surprising results: Cows nearly always line up with the magnetic north or south poles while grazing.
The Whole Bushel
We’ve known for a long time that certain birds and fish use the Earth’s magnetic field as a sort of guide. But can large mammals do the same? Well, if you believe the scientists at the University of Duisburg-Essen, then the answer is a resounding “yes.”
Way back in 2008, Dr. Sabine Begall and her colleagues were investigating how rodents responded to magnetic fields. Perhaps bored with shoving lumps of metal into rats’ faces all day long, they decided to broaden their research to include larger mammals. Taking to Google Earth, the team analyzed satellite images of hundreds of cattle herds taken across the globe. The results were suitably strange: They found that grazing cows nearly always face magnetic north or magnetic south.
This was unexpected to say the least. Unlike birds or salmon, cows rarely migrate long distances or do much of anything, except maybe chew some cud. So why evolution might endow them with the ability to line up along magnetic lines was a total mystery. Yet the team’s work showed that they did it. Of all the cows analyzed, most faced no more than five degrees off north or south. Nor were they the only ones: Subsequent analysis of tracks made in snow showed that deer herds seem to do the same thing.
After some careful thinking, the scientists came up with a workable theory. Many, many years ago, cows and deer would have originally lived in dense forests, on wide open plains and other places without landmarks. In a world with no discernible way of telling one direction from another, an ability to sense magnetic lines could well give an evolutionary advantage. So that’s that sorted. As for how cows might perceive these magnetic fields, it was summed it up best when one of them simply stated, “I have no real idea.”