How can some animals find their way back to home?
I t is presently a mystery how some lost animals - usually cats and dogs - find their way home. A recent case was Pero (1), a four-year sheepdog which was back to home 15 days later after its scape. Somehow Pero was able to find its home 240 miles (~400 km) away. Many other "anecdotes" accumulate, narrated by many families and now Pero's case seems to have confirmed this surprising ability. According to the present scientific knowledge, animals are endowed with a multitude of "sensors" (2) used to provide accurate information and supporting the notion that they are able to guide themselves through long distances. Such sensor are not only far superior than the human versions (dogs, for example, have acute smell and hearing, cats see very well in the dark etc), but represent perhaps other sense modes as, for example, magnetic sensing. Birds and bees have their own inner "compasses". Magnetic substances have been found in the retina of many animal...