Occasionally you hear some news and wonder “Why didn’t I ever hear about this before?” That was my reaction to the news that scientists have been investigating something called “quantum biology” for the past 20 years or so.
Last week, there was a link on the always interesting Self Aware Patterns blog to a Guardian article called “You’re Powered by Quantum Mechanics. No, Really…”. The article was written by two scientists, the physicist Jim Al-Khalili and the geneticist Johnjoe McFadden. Here’s the news I found extremely surprising:
As 21st-century biology probes the dynamics of ever-smaller systems – even individual atoms and molecules inside living cells – the signs of quantum mechanical behaviour in the building blocks of life are becoming increasingly apparent. Recent research indicates that some of life’s most fundamental processes do indeed depend on weirdness welling up from the quantum undercurrent of reality.
Really? People with various qualifications have speculated for years about quantum mechanical phenomena occurring in the human brain, usually in an attempt to justify belief in free will. But this is real science based on experimental results (albeit with a dose of speculation too).
The McFadden/Al-Khalili article cites three examples in which quantum phenomena appear to play a crucial role in biology. First, enzymes appear to work via quantum tunneling:
Enzymes … speed up chemical reactions so that processes that would otherwise take thousands of years proceed in seconds inside living cells. Life would be impossible without them. But how they accelerate chemical reactions by such enormous factors, often more than a trillion-fold, has been an enigma. Experiments over the past few decades, however, have shown that enzymes make use of a remarkable trick called quantum tunnelling to accelerate biochemical reactions. Essentially, the enzyme encourages electrons and protons to vanish from one position in a biomolecule and instantly rematerialise in another, without passing through the gap in between – a kind of quantum teleportation.
Second, photosynthesis seems to involve wave/particle duality:
The first step in photosynthesis is the capture of a tiny packet of energy from sunlight that then has to hop through a forest of chlorophyll molecules …. The problem is understanding how the packet of energy appears to so unerringly find the quickest route through the forest. An ingenious experiment … revealed that the energy packet was not hopping haphazardly about, but performing a neat quantum trick. Instead of behaving like a localised particle travelling along a single route, it behaves quantum mechanically, like a spread-out wave, and samples all possible routes at once to find the quickest way.
Third, there are animals who appear to rely on quantum entanglement:
A third example of quantum trickery in biology … is the mechanism by which birds and other animals make use of the Earth’s magnetic field for navigation. Studies of the European robin suggest that it has an internal chemical compass that utilises an astonishing quantum concept called entanglement, which Einstein dismissed as “spooky action at a distance”. This phenomenon describes how two separated particles can remain instantaneously connected via a weird quantum link. The current best guess is that this takes place inside a protein in the bird’s eye, where quantum entanglement makes a pair of electrons highly sensitive to the angle of orientation of the Earth’s magnetic field, allowing the bird to “see” which way it needs to fly.
McFadden has published another article at Aeon in which he further discusses the examples above and throws in a possible relationship between quantum mechanics and the sense of smell. In addition, a quick search online turned up an article from the MIT Technology Review explaining how quantum entanglement may stop large DNA molecules from falling apart and an overview of developments in quantum biology from the BBC.
Not everyone is convinced of the quantum nature of these phenomena, of course, and research continues. Still, I think this is all extremely interesting. In one sense, it’s surprising that living things could employ phenomena like entanglement and quantum tunneling that seem so bizarre and so removed from ordinary life. But in another sense, it shouldn’t be a surprise if millions of years of evolution have allowed both plants and animals to take advantage of such powerful and fundamental natural phenomena.