© David Staume 2006

What does it mean when we can't define 'life'?

I have a Penguin Reference book called A Dictionary of Biology on my bookshelf, and when I look up the word ‘biology’ it says ‘the study of living things’. So I look up ‘living things’, and find that there’s no entry. OK, no problem, I’ll try under ‘life’. So I look up ‘life’ and … enter a weird biological twilight zone … for there’s no entry for ‘life’ in my dictionary of biology. A dictionary of biology with no definition of ‘life’? You have to be joking! My six year old daughter could come up with something – even if it’s ‘if you poke it and it wiggles, it’s alive’.

My Houghton Mifflin eReference dictionary starts its definition of ‘life’ with ‘The property or quality that distinguishes living organisms from dead organisms’, which cracks me up every time. Yes, everyone is searching for the meaning of life, but if you’re doing it with a dictionary you’re unlikely to be successful. ‘Life’ is one of life’s greatest mysteries.

So what’s the problem with defining life?

When we look at the world and see how it’s organized, we see a few natural, broad groupings. We see a mineral kingdom – which we consider as ‘non-living’ - and a plant kingdom, animal kingdom, and human kingdom – which we consider as ‘living’. But what exactly is the mysterious ‘it’ of life that leaves the mineral kingdom cruelly to one side?

‘Poke it and it wiggles’ doesn’t work because while you can poke rocks and they’re not likely to wiggle, you can poke me in my sleep and I’m not likely to wiggle either – I can sleep through anything. But it also breaks down on other occasions, such as when you poke a seed, because seeds have the mysterious ‘it’ of life, but won’t wiggle when poked.

Define life as ‘the ability to reproduce’ and for the first few moments you think you’ve cracked the puzzle, until you realize that the infertile couple you know wouldn’t be very happy with being called 'dead'. Ah, but that’s just a couple – the human kingdom as a whole has the capacity to reproduce. But if the earth was irradiated with cosmic rays that fried every human ova and sperm but left us otherwise unharmed, the definition fails again. The human race would then not have the capacity to reproduce - and so would die out soon – but in the meantime we would certainly be alive.

Define life as ‘the capacity for growth, movement and change’ and you have the unhelpful situation of everything being alive. All the kingdoms show examples of growth, movement, and change. Examples of these are obvious in the plant, animal, and human kingdoms, but less so in the mineral kingdom. But while the mineral kingdom has an enduring quality, minerals change. It’s just that they change very slowly. Minerals change in composition, texture, and internal structure under the influences of such things as heat, pressure, and new chemical substances.Crystals grow, and metals fatigue under repeated stress. And even if you say that an individual stone doesn’t possess life-like qualities, the mineral kingdom as a whole is constantly engaged in the processes of moving continents, creating new islands through volcanic activity, grinding up rocks for sand, and taking planets and stars through their life-cycles.

Define life as ‘possession of instinct’ and you have to define ‘instinct’. Define instinct as ‘an inborn pattern of behaviour’ and everything’s miraculously alive again, because even simple elements possess inborn patterns of behaviour. Define life as ‘complexity’ and the Windows operating system just developed a pulse. Define life as ‘a metabolic process’ and then divide this process into catabolism (breaking down) and anabolism (building up), and you realize that this process occurs in sedimentary rocks. Define life as ‘the possession of consciousness’ and you’ve chosen a criteria that you can’t measure, and so what’s alive and what isn’t becomes hopelessly subjective.

So there’s the problem.

And so we sit and wait, hoping that we’ll find a definition somewhere in the future, or else avoiding the dilemma and hoping that it will go away.

But neither of those things are likely to happen. Let’s face it, ‘life’ is probably unable to be defined!

And when you say that, something remarkable happens. The admission of defeat doesn’t close the door to understanding life, it opens a new one, because it makes us ask ‘Why?’ Why would something be unable to be defined? One reason is that the term is infinite – because it’s impossible to define something infinite in finite terms; but I'm wary of arguments that involve infinities. Another reason why something could be unable to be defined is that the term is meaningless – because the term, for example, includes everything … absolutely everything!

Which, funnily enough, and coming full circle, gives us an excellent reason not to find a definition of 'life' in the dictionary. The term is meaningless. And it's meaningless because everything is alive. Something to ponder.

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