MAGNETIC MOMENTS - Snowball Earth - page 36

northern hemisphere the Earth's magnetic field lines slant downwards, so for the bacteria “north”
equals “down” equals “food”. To find food, they simply clamp their internal magnets on to the Earth's
slanting field lines and slide down, like firemen down a pole.
Joe was in Australia when he heard about these strange magnetic bacteria. He knew that in the
southern hemisphere, the Earth's field lines pointed the opposite way, so that “north” there was “up”.
What, he wondered, happened to southern bacteria? He immediately rushed off to find likely looking
grubby ponds and pools of water, and snared a few bacteria. Using the magnifying glass and magnet
that he always carried with him, he found that Australian bacteria swam consistently south. Their in-
ner magnets were upside down compared with those of their northern cousins. 1
The Aussies loved it. Joe found himself unexpectedly on the front page of the Canberra Times ,
brandishing a beaker of bacterial sludge from the Fyshwick Sewage Works. He knocked the Ayatollah
Khomeini off the headlines. His south-seeking bacteria became celebrities. Joe set them up at a Can-
berra University party so geologists could watch them swimming backwards and forwards as he
flipped a magnet below them. One partygoer, peering over his shoulder, asked if they liked beer. Joe
promptly applied a drop of Foster's lager to one side of the beaker, and then flipped the magnet to
make that side “south”. The bacteria galloped toward the spreading yellow liquid, but as soon as they
tasted it, they turned tail. Australian bacteria apparently do not like beer. Later, Joetested the northern
bacteria in his hometown of Phoenix, Arizona. The American bacteria showed no inclination to turn
tail at the Foster's-water interface. They swam directly into the beer, and promptly perished. “They
died happy,” says Joe. American bacteria, unlike Australian, have no idea when to call it a day.
Joe was just fooling around with the beer, but these experiments had an underlying seriousness. He
became intrigued by the way the Earth's magnetic field affected the creatures on its surface. At Prin-
ceton as a graduate student, he discovered tiny, pure magnets in the brains of honeybees and pigeons
and proved—to everyone's astonishment—that the creatures use these in-built magnets to navigate. 2
This was a classic case of finding a scientific basis for ideas that had previously been ridiculed. Pigeon
fanciers had long believed they should not race their birds when there was a magnetic storm. Beekeep-
ers were convinced their charges had an innate sense of direction. Nobody else believed them. Joe put
science where the myths had been. His findings, made while he was still a student, are now described
in even the most staid of textbooks.
Joe also found magnets in the brains of fish, whales and even humans. 3 Thanks to Joe, it's now
known that we all carry tiny, built-in magnets around in our heads. These magnets may even help hu-
mans navigate, although Joe never managed to prove that we use our magnets the way bees and pi-
geons do.
Joe's obsession with magnets even extends to the names of his children. His wife, Atsuko, is
Japanese, and his sons are called Jiseki, which means “magnetite” in Japanese, and Koseki, which
means “mineral”. Jiseki came first, in 1984. As the firstborn son, with a lineage that traced back
through Atsuko to the Japanese imperial family, the child had to be given a distinctive and meaningful
name—one that would be approved by the temple monk back in Japan. This approval hinged crucially
on how the name looked when written down. One night, after many fruitless suggestions, Joe asked
his wife what “magnetite” would look like. She wrote down Jiseki. The name had a curious shape, like
two lightning bolts next to one stone over another. Atsuko called her mother in Japan, who immedi-
ately took the name to the temple. It passed every test that the monk set.
Koseki, “mineral”, appeared two years later. Though his name didn't pass quite as many temple
tests, it was still perfectly acceptable, and everyone agreed that it was the natural follow-up. And if
there had been a third child? This is what Joe says about the name that would have been next. “As well