No, but I put strawberries in bags all the time and carry them back from the supermarket.
Robin: Can I just say he doesn’t come back from the supermarket with strawberries, he has a man that works for him who comes back with the strawberries from the supermarket…
Series 8, Episode 1 (24 June 2013)
So how do you murder a strawberry?
Whether boiling or freezing it, you are preventing the seed from ever germinating, curtailing the potential of the strawberry and yet increasing its potential too. Who wants to be a live and unknown strawberry when you could be a celebrated dead one smeared on a scone in Torquay? For a strawberry, a frog or a human, that is the key to life over death: do you still have potential? This page is in memory of all the strawberries that have died for us. Your death was delicious.
Brian replies…
Strawberries are inaccurately named, counter-intuitive things. The strawberry is not a berry: the red fruit is part of the stem of the plant from which the flower organs grow. The things we call the seeds – the little pits on the fruit – are not seeds, they are the plant’s ovaries, and the seeds reside inside. So is a strawberry dead or alive?
In the original episode of The Infinite Monkey Cage where I first posed the strawberry death question, Professor Matthew Cobb, from the University of Manchester, answered, ‘As soon as you pick a strawberry, it’s dying. As it decays it increases its sugar content, and that is what makes it sweet, but essentially it is dying.’ This is correct for the berry as a whole, which is a part of the plant and will decay if it isn’t attached. The strawberry no longer has access to the supply of ordered energy from the Sun that a plant uses to maintain its structure through photosynthesis, and the Second Law of Thermodynamics does the rest.
The Second Law of Thermodynamics is arguably the only law of nature that we currently possess that is actually a law, which is to say physicists believe that it is absolutely right. Quantum Theory and General Relativity may one day be refined or even replaced, but the Second Law of Thermodynamics will surely still stand. It states that, over time, an isolated system will become more disordered. In simple terms: Things Can Only Get Worse.
If a teacup falls to the ground, it smashes into pieces, and we never see the pieces spontaneously reassemble into a teacup, even though there is nothing in the laws that govern the motion of the constituent molecules that prevents it. The reason is that there are many more ways of arranging the molecules such that they form a pile of bits on the floor than the very specific arrangement that makes a teacup. A teacup is an unlikely arrangement of molecules, given that all arrangements are equally likely.
Living things certainly seem to run counter to this law. A strawberry is one of the most complex things we know of in the Universe, and it is at first sight hard to see how this can be squared with the Second Law. This has become known as Schrödinger’s Paradox. The resolution to the paradox is relatively straightforward. The strawberry is not an isolated system: when the strawberry is attached to a living plant, it is part of a system that includes the heat of the Sun and the coldness of space. The Sun is a source of high-energy photons cascading down onto the leaves. The plant absorbs these photons and uses their energy to convert carbon dioxide and water into sugar and oxygen through photosynthesis. Sugar is more complex than carbon dioxide and water; the atoms have been rearranged into a more ordered structure, just like a teacup. This is not all that happens, however. The plant radiates heat out into its surroundings, which is in turn radiated into the coldness of space. Heat is also a stream of photons, but they are lower energy and more numerous than those in the incoming sunlight. Heat is a highly disordered form of energy, and when all the sums are done, it turns out that this more than compensates for the increase in order during the formation of sugars and the other intricate structures of the strawberry. We might say that the strawberry increases the amount of disorder in the Universe quicker by the very fact of its existence, thus hastening the demise of all of creation. It borrowed order from the Sun, but increased the disorder of the rest of the Universe as a result.
The moment that the strawberry’s metabolism grinds to a halt, it can no longer function as a little machine sitting between the cascade of ordered energy from the Sun and the coldness of space, and the Second Law reasserts its grip. This is death.
The seeds inside the ovaries attached to the fruit are a different matter, however. They are alive if they are capable of germinating. Seeds can stay dormant for very long periods of time; many decades in some instances, and there are different types of dormancy in the plant kingdom. The strawberry seed exhibits physical dormancy, which means that the seeds’ outer casing, being impermeable to water, prevents the embryo within germinating – germination is defined as the sprouting of the seedling from the seed. When the strawberry is eaten by an animal, the seeds pass through the digestive tract and the outer casing is damaged such that it becomes permeable to water. This begins the germination process. In other species, the outer casing can be damaged by fluctuating temperatures, freezing and thawing, drying, or even fire. The evolutionary advantage of delayed germination is clear; there is a selective advantage to delaying germination until the onset of the rainy season in the tropics, for example. Awaiting dispersal via consumption by an animal can also be seen to offer a selective advantage. Precisely how physical dormancy evolved, however, is a matter of ongoing research.
Some seeds exhibit a different form of dormancy known as physiological dormancy, in which embryo growth is prevented by inhibiting chemicals. All gymnosperms – of which conifers are the most common group – exhibit physiological dormancy. Unlike physical dormancy, physiological dormancy can be reversible.
The definition of a dead strawberry is therefore a slippery one, and depends on whether you mean the strawberry itself (which is not a berry), or the seeds it contains. In the simplest terms, Professor Nick Lane, from University College London, stated that if the strawberry is not continually harnessing energy to maintain being alive, it’s dead. Seeds can continue to metabolise, albeit extremely slowly, whilst dormant. They are therefore alive, until they stop.
Brian noted that our understanding of the plight of a strawberry might be further complicated by taking quantum theory into account, extending the discussion to Schrödinger’s Strawberry.
R: I’ll tell you what, we’ll put a strawberry in a box and we won’t observe it and it can be both.
Katy: I love the idea of Shrödinger’s Strawberry.
R: The whole of Wimbledon changes.
B: I’m thinking about how you’d write down the wave function of a strawberry.
R: When are you not thinking of a wave function…?
Series 7, Episode 2 (26 November 2012)
