A Short History of Nearly Everything

by Bill Bryson

99.99 per cent, it has been suggested – are no longer around. Life on Earth,

It is a curious feature of our existence that we come from a planet that is very good at promoting life but even better at extinguishing it.

The average species on Earth lasts for only about fo...

But because lead is for ever, Americans alive today each have about 625 times more lead in their blood than people did a century ago22

The upshot of all this is that we live in a universe whose age we can’t quite compute, surrounded by stars whose distances from us and each other we don’t altogether know, filled with matter we can’t identify, operating in conformance with physical laws whose properties we don’t truly understand.

So powerful is this natural impulse to assemble that many scientists now believe that life may be more inevitable than we think – that it is, in the words of the Belgian biochemist and Nobel laureate Christian de Duve, ‘an obligatory manifestation of matter10, bound to arise wherever conditions are appropriate’.

At some point in an unimaginably distant past some little bag of chemicals fidgeted to life. It absorbed some nutrients, gently pulsed, had a brief existence. This much may have happened before, perhaps many times. But this ancestral packet did something additional and extraordinary: it cleaved itself and produced an heir.

The process is thought to have started when some blundering or adventuresome bacterium either invaded or was captured by some other bacterium and it turned out that this suited them both. The captive bacterium became, it is thought, a mitochondrion. This mitochondrial invasion (or endosymbiotic event, as biologists like to term it) made complex life possible.

Every human body consists of about ten quadrillion cells, but is host to about a hundred quadrillion bacterial cells

The First World War killed 21 million people in four years; swine flu did the same in its first four months51. Almost 80 per cent of American casualties in the First World War came not from enemy fire, but from flu. In some units the mortality rate was as high as 80 per cent.

Indeed, if your pillow is six years old – which is apparently about the average age for a pillow – it has been estimated that one tenth of its weight will be made up of ‘sloughed skin, living mites, dead mites and mite dung’, to quote the man who did the measuring, Dr John Maunder of the British Medical Entomology Centre27. (But at least they are your mites. Think of what you snuggle up with each time you climb into a hotel bed.)fn3 These mites have been with us since time immemorial28, but they weren’t discovered until 1965.

Most of the time our DNA replicates with dutiful accuracy, but just occasionally – about one time in a million – a letter gets into the wrong place. This is known as a single nucleotide polymorphism, or SNP, familiarly known to biochemists as a ‘Snip’. Generally these Snips are buried in stretches of non-coding DNA and have no detectable consequence for the body. But occasionally they make a difference.

The genome, as Eric Lander of MIT has put it, is like a parts list for the human body: it tells us what we are made of, but says nothing about how we work. What’s needed now is the operating manual – instructions for how to make it go. We are not close to that point yet. So now the quest is to

if you were designing an organism to look after life in our lonely cosmos, to monitor where it is going and keep a record of where it has been, you wouldn’t choose human beings for the job.

To attain any kind of life at all in this universe of ours appears to be quite an achievement. As humans we are doubly lucky, of course. We enjoy not only the privilege of existence, but also the singular ability to appreciate it and even, in a multitude of ways, to make it better. It is a trick we have only just begun to grasp.