This is an amazing discovery. It’s been known, of course, that some birds (and other animals) are capable of detecting the earth’s magnetic field. This is what gives them a sense of direction, and they seem to know exactly where they are going. Until now, exactly how this detection happened was not completely known, although it was guessed that vision was involved.
Here’s the latest:
This ‘compass’ sense must be associated with the eyeball, because the birds cannot detect magnetic fields in darkness.
But now Oxford University and National University of Singapore scientists have shown that birds may really ‘see’ the invisible force of magnetism, giving them a compass on top of their normal vision: rather like aircraft ‘head up displays’ which overlay crucial navigation information on a transparent screen in front of the pilot.
The ‘technology’, so to speak, involves a special molecule in the eye. When a photon of light enters the eye and hits the molecule, it causes an electromagnetic effect in the eye—and since this effect also depends on the surrounding magnetic field, the effect translates into a ‘map’ of the earth’s magnetic field. All this, right in the eye of the bird!
The next question, I guess, ought to be: is the absence of light the only reason that the birds can’t navigate at night? Would they do fine if there was artificial ambient light at night? What happens if they are fitted out with a ‘headlamp’ of sorts, that reflects light back into their retinas? Is there a minimum amount of light that would be the threshold? This is all very exciting.
In related news, a protein in the human retina has previously been found to possess magnetic properties. This is possibly remnants of the same system—which poses the question: did humans ever have the capacity to detect magnetic fields? Is this a rudimentary evolutionary leftover, or did we shed our sensing capabilities as we gave up our migratory habits and settled down to a life of agriculture?
Really—the more we find out about nature, the more amazing it all is. (Well, granted—the Earth has had a few million years to test and improve new technology, but you’ve got to admit, this is pretty cool.)