Also in this week's column:

• Who knows what there is to know about the nose?

Asked by Lee Staniforth of Manchester, UK

Some years ago scientists at CALTECH (California Institute of Technology in Pasadena) discovered that humans possess a tiny, shiny crystal of magnetite in the ethmoid bone, located between your eyes, just behind the nose.

Magnetite is a magnetic mineral also possessed by homing pigeons, migratory salmon, dolphins, honeybees, and bats. Indeed, some bacteria even contain strands of magnetite that function, according to Dr Charles Walcott of the Cornell Laboratory of Ornithology in Ithaca, New York, "as tiny compass needles, allowing them [the bacteria] to orient themselves in the earth's magnetic field and swim down to their happy home in the mud".

It seems that magnetite helps direction finding in animals and helps migratory species migrate successfully by allowing them to draw upon the earth's magnetic fields. But scientists are not sure how they do this.

In any case, when it comes to humans, according to some experts, magnetite makes the ethmoid bone sensitive to the earth's magnetic field and helps your sense of direction.

Some, such as Dr Dennis J Walmsley and W Epps from the Department of Human Geography of the Australian National University in Canberra writing in Perceptual and Motor Skills as far back as in 1987, have even suggested that this "compass" was helpful in human evolution as it made migration and hunting easier.

Following this fascinating factoid, science journalist Marc McCutcheon entitled a book The Compass in Your Nose and Other Astonishing Facts.

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au

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