Life Ascending: The Ten Great Inventions of Evolution

Shrink yourself down to the size of, say, an ATP molecule, and the cell is a vast cityscape of the future. Stretching as far as you can see in all directions is a giddying array of cables, buttressed with yet more cables. Some look flimsy and thin, while others are of great diameter. In this metropolis of the cell, gravity means nothing, viscosity is everything, and the random jiggling of atoms is all about. Try to move and you will find yourself stuck as if in treacle, yet at once buffeted and jogged from all sides. And suddenly, through this dizzying city comes a peculiar machine, moving at startling speed, hand-over-mechanical-hand, using one of the cables for a track. Attached to this hurtling machine through an unwieldy coupling device is a truly vast object, towed along at speed. If you were in the way, it would be like being hit by a flying power station. Indeed, this is just what it is—it's a mitochondrion, on its way to power the major works over on the other side of the city. And now that you look, various other objects are all heading in the same direction, some faster, some slower, but all towed along the tracks in the sky by similar machines. And whoomp! As the mitochondrion passes, you are caught up in the slipstream, whirled along in the vortex. You are part of the constant circulation that stirs the contents of all complex cells, the cytoplasmic stream.

Thermodynamics is one of those words best avoided in a book with any pretence to be popular, but it's more engaging if it's seen for what it is: the science of 'desire'. The existence of atoms and molecules is dominated by 'attractions', 'repulsions', 'wants' and 'discharges', to the point that it becomes virtually imposs

Thermodynamics is one of those words best avoided in a book with any pretence to be popular, but it's more engaging if it's seen for what it is: the science of 'desire'. The existence of atoms and molecules is dominated by 'attractions', 'repulsions', 'wants' and 'discharges', to the point that it becomes virtually impossible to write about chemistry without giving in to some sort of randy anthropomorphism. Molecules 'want' to lose or gain electrons; attract opposite charges, repulse similar charges; or cohabit with molecules of similar character. A chemical reaction happens spontaneously if all the molecular partners desire to participate; or they can be pressed to react unwillingly through greater force. And of course some molecules really want to react but find it hard to overcome their innate shyness. A little gentle flirtation might prompt a massive release of lust, a discharge of pure energy. But perhaps I should stop there.

If Martin and Russell are right - and I think they are - [the Last Universal Common Ancestor] was not a free-living cell but a rocky labyrinth of mineral cells, lined with catalytic walls composed of iron, sulphur and nickle, and energised by natural proton gradients. The first life was a porous rock that generated complex molecules and energy, right up to the formation of proteins and DNA itself.

Crick pictured messenger RNA just sitting in the cytoplasm with its codons projecting like a sow's nipples, each one ready to bind its transfer RNA like a suckling pig. Eventually all the tRNAs would nestle up, side by side down the full length of the messenger RNA, with their amino acids projecting out like the tails of piglets, ready to be zipped up into a protein.

One scientist, on first reading Wächtershäuser's wok, remarked that it felt like stumbling across a scientific paper that had fallen through a time warp from the end of the twenty-first century.

But is he right? Harsh criticism has been levelled at Wächtershäuser too, in part because he is a genuine revolutionary, overturning long-cherished ideas; in part, because his haughty manner tends to exasperate fellow scientists; and in part, because there are legitimate misgivings about the picture he paints.

In the face of little solid evidence, I'd like to raise another gloriously imaginative hypothesis from the ingenious duo we met in Chapter 2, Bill Martin and Eugene Koonin. Their idea has two great merits. It explains why a nucleus should evolve specifically in a chimeric cell, notably one that is half archaea, half bacteria (which, as we've seen, is the most believable origin of the eukaryotic cell itself). And it explains why the nuclei of virtually all eukarytoic cells should be stuffed with DNA coding for nothing, completely unlike bacteria. Even if the idea is wrong, I think it's the kind of thing we ought to be looking for, and it still raises a real problem facing the early eukaryotes that has to be solved somehow. This is the sort of idea that adds magic to science, and I hope it is right.