How Migratory birds and animals managed to find their way around the globe has been a mystery for centuries. We know that they apply a variety of methods:
- Some use solar navigation during the day and celestial navigation at night
- Some memorize landmarks
- Some can even smell their way around the planet
But the most mysterious navigational sense of all is the one possessed by the European Robin: The ability to detect the direction and strength of the earth’s magnetic field, known as ‘Magnetoreception’. And while we now know of a number of other creatures that possess this ability, it is the way the European Robin (Erithacus Rubecula) finds its way across the globe that is of greatest interest to the scientific world.
The mechanism that enables the robin to know how far to fly, and in which direction is encoded in the DNA of Robin’s and other migratory birds has inherited from their parents. This ability of Robin’s is sophisticated and most uncommon one – a sixth sense that Robin’s uses to plot their course. Like many other migratory birds, and indeed insects and marine creatures, Robin has the ability to sense the earth’s weak magnetic field and to draw direction information from it by way of an inbuilt navigational sense, which is Robin’s case requires a novel type of chemical compass.
How Magnetoreception helps migratory birds?
Here now we heard the term “Magnetoreception” but this Magnetoreception itself a big enigma to the scientific world because earth’s magnetic field is very week – between 30 to 70 microtesla at the surface: sufficient deflect a finally balanced and almost frictionless compass needle, but only about a hundredth the force of a typical fridge magnet. This presents a puzzle: for the earth magnetic field to be detected by an animal it must somehow influence a chemical reaction somewhere in the animal’s body – this is after all, how all living creatures, ourselves included, sense any external signal. But the amount of energy supplied by the interaction of the earth’s magnetic field with the molecules within the living cell is less than a billionth of the energy needed to break or make chemical bond.
How, then, can that magnetic field perceptible to the European Robins and other Migratory birds? Is it still a mystery?
But to an extent scientist could able to decipher this mysterious ability of the European Robin’s and other migratory birds to find its way across the globe with the help of quantum mechanics.
But what has any of this to do with quantum mechanics and particle physics?
The answer to this will be the continuation of “Magnetoreception” ability of European Robin and other migratory birds – the ability to detect the earth’s magnetic field. Many creatures including fruit flies, butterflies also has a capability of magnetoreception, particularly in European Robins, has the poster child of quantum biology.
The Avian Compass
Our planet is a giant magnet, with a magnetic field of influence that extends from its inner core all the way out into space for 1000 of miles. This magnetized bubble, the “magnetosphere”, protect all the life on our earth, because without this magnetic field of influence from our planet earth, the solar wind – the stream of energetic particles emitted from the sun – would have long ago eroded our atmosphere. And this electromagnetic field is very much unlike to the magnetism of a typical bar magnet, the earth’s magnetic field changes time to time, because its origins is from inside the earth’s molten iron core and the exact origin of this magnetism is complicated, but it is thought to be due to what is known as a geodynamo effect, whereby electric currents are generated by the circulation of metals in the core of earth, which results to generate a magnetic field.
All the life on earth is because of the existence of this protective magnetic shield and its usefulness to living creatures is endless; scientists have known for over a century that many living species have evolved ingenious ways of making use of this protective magnetic shield of this planet. As human sailors used earth’s magnetic field for thousands of years to navigate the oceans, so many of earth’s other creatures, including marine and terrestrial mammals, birds(such as European Robin and other migratory birds) and insects have evolved over millions of years a sense that detects the earth’s magnetic field and uses this to navigate.
Theory of Henry Yeagley
Following to the work “Avian Navigation” by Henry Yeagley an American Physicist carried out a research for the US Army Signal Corps during the second world war. Avian navigation was of interest to the military because homing pigeons were still being used to carry messages and aviation engineers hope to learn from their navigation capabilities. Yet how the birds manage to find their way home so unerringly remind a mystery. Henry Yeagley developed a theory that homing pigeons could sense both the earth’s rotation and its magnetic field. This, he claimed, would create a ‘navigational grid work’ in the bird’s brain, giving it both the longitude and latitude coordinates. Henry Yeagley also tested this theory by attaching small magnets to the wings of 10 pigeons and nonmagnetic strips of copper of the same weight to ten other pigeons. Eight of the ten pigeons with copper strips attached to their wings found their way home, but only one of the ten pigeons with magnets attached to their wings managed to reach their nest, Henry Yeagley concluded that the birds utilize a magnetic navigational sense to navigate, which could be disrupted by magnetic strips.
The ability of the animals to detect the earth’s magnetic field is no longer in doubt. The mystery is how they do it because the earth’s magnetic field is extraordinarily weak and wouldn’t normally be expected to influence any chemical reaction in the body. There are two principle theories and both are likely to be involved in the different animal species
- The first is that the animal sense functions like a conventional magnetic compass – the conventional compass mechanism resides somewhere in an animal’s body, was bolstered by the discovery of tiny crystals of magnetite, the naturally occurring magnetic Iron Oxide mineral, in many of the animals and microbes that seem to possess a magnetic sense.
- And the second is that the magnetoreception is conferred by a Chemical Compass
To be continued with more explanations to this theories with the help of “quantum mechanics” and the mysterious quantum world phenomenon such as quantum entanglement(which is so strange that even Einstein insisted that it could not be correct) and “quantum spin”