Alien Scientist 40: The Stuff of Life
Stephen Marshall, a former resident of Tsukuba, has been writing Alien Scientist articles for the Alien Times since 2001. Even though he no longer lives in Tsukuba, he is still a regular contributor to the magazine. Here is his latest intergalactic report.
In 1828 Friedrich Wöhler synthesised urea: the first time an organic compound had been synthesised from an inorganic one. This demonstrated that living things were not made of some special ‘vitalistic’ matter, separate from non-living matter, but were made up of the same old chemicals as everything else: the common dust of the Earth, after all. Life as we know it is based more particularly on the chemical element carbon. Carbon forms long chain molecules that form so many types of compound useful for doing so many things. Carbon not only helps to build our bodies, but helps keep them running. Carbon makes up proteins, fats, sugars, carbohydrates and vitamins – in a word, food. So useful is carbon, indeed, for forming the building-blocks of life, that carbon chemistry is considered the most likely basis for any extraterrestrial life.
Of course, alien perspectives on life are not just about alien organisms and their lifestyles – hypothetical carbon creatures and their even more hypothetical diets – but invite reflection more generally on the organic nature of carbon chemistry, and how chemistry is interwoven with biology.
In his book The Periodic Table, Primo Levi imagines the ‘life story’ of a carbon atom. As part of its eternal chemical journey, the carbon atom that is the hero of the story is absorbed from the atmosphere, through photosynthesis, into the leaves and then woody stem of a cedar tree, whence it is eaten by a worm that becomes a moth, that on death decomposes, once more releasing the carbon atom back into the air. Levi’s story of this ‘carbon cycle’ would be satisfying enough viewed from the point of view of the atmosphere, soil, plants and animals, but is all the more vivid for portraying events from the point of view of the atom. Here the carbon atom is behaving as if taking part in a series of merry dances, bonding first with this atom, and then that; mingling here in the intimate company of two oxygen atoms, or there swept up into the hexagonal formation of glucose, or a long chain ‘conger’ of cellulose.
In all this, the carbon atom – that is, after all, not in reality a living entity – yet forms part of larger wholes that are alive, at least for some parts of the journey. From the carbon atom’s point of view, it passes effortlessly from the lifeless gas of carbon dioxide to being part of a living plant or animal and back again. The carbon atom continues to exist – ‘lives on’ – after the death of the host to which it belongs. Perhaps the carbon atom – were it somehow endowed with consciousness – would hardly care to distinguish whether the compounds it formed were part of living beings or not. Indeed these might often be practically indistinguishable – whether being part of the recently living lettuce freshly plucked from the ground, or the tiger-prawn in the deep-freeze. In either case, the carbon is fixed into an organic architecture that exists as such even if no longer forming part of a living organism.
From another point of view, perhaps the carbon atom, as it is swept around in its chemical choreography, is caught up in a great mechanism of life, like a ball in a pachinko machine. The pachinko machine is clacking and whirring and churning as if it were alive, although no individual ball, no individual part is alive. Or the carbon atom is like an individual spectator in a sports stadium, leaping up and down as part of the crowd to propagate a ‘Mexican wave’. Here, the wave seems to have a life of its own, behaving in a way that is different in kind from the leaping-up-and-down of the individual spectators. The spectators need not themselves be alive – they could be simply robots – for the stadium wave to have its own kind of transient existence. Of course, we could point out that the pachinko machine and the stadium wave are not really alive – any more than the carbon atom itself is alive. But then, a certain view of the universe would speculate that life itself could be just an illusion. An organism could, like the pachinko machine, be seemingly alive, but ultimately no more than the sum of individually inert components, like a package of balls, cogs and springs. In this view, we too would all just be automata; and the illusion of life or its specialness is just another anthropocentric – or vivocentric – conceit.