How to Make a Human Being: A Body of Evidence. Christopher Potter
cannot myself see just how we shall ever decide how life originated.
Francis Crick
If you study life and you’re not flabbergasted by the hypothesis of evolution, you just haven’t looked carefully enough. I think it’s a tragedy that nobody walks into a class and expresses that wonder … We have no evidence that life is not a miracle, i.e. a very low probability event. And we should give that one away and say we don’t know the hell where it came from. If you want to believe in God at that point, it’s as good a theory as any other, but no one will say that, and that is a pity. It all has to be in the running.
From a conversation between a scientist and the author
The universe has the curious property of making living beings think that its unusual properties are unsympathetic to the existence of life when in fact they are essential for it.
John Barrow, theoretical physicist
The more I study the universe and study the details of its architecture, the more evidence I find that the universe in some sense must have known we were coming.
Freeman Dyson, theoretical physicist
6 | If any of the constants of nature – the mass of the electron, say – were different, so would the whole universe be.
7 | The early solar system was a violent place not conducive to life as we know it. A disk of dust orbiting our sun accreted under gravity and multiple collisions into numerous objects larger than dust-sized. After many such collisions and over a long period of time these numerous objects came together as planets and asteroids. Once these large objects had settled into fixed orbits and got out of the way of each other, the solar system gradually became a place where collisions are rare events rather than the norm.
Life on earth would not be possible if the earth’s orbit was a little more elliptical than it is. The earth would repeatedly travel outside the narrow zone in which life as we know it here is sustainable.
Life on earth was not possible until the earth’s temperature stopped varying so wildly. It took most of the earth’s 4,500-million-year history before this was the case. The gradual stabilisation of the amount of carbon dioxide (and other so-called greenhouse gases) in the atmosphere has played an important role in the stabilisation of the earth’s temperature. (Through the interference of humans, that stabilisation is being tested.)
Life would not be possible without water. At some point in the earth’s deep history the atmosphere begins to fill with water vapour. There is a day when it rains for the first time. Some of the oldest fossil remains are of the indentations of rain made in rocks discovered in India. They are at least three billion years old, though by then it had been raining for at least a billion years.
Life would not be possible if water did not have the unusual property of being less dense in its liquid state than in its solid state, otherwise the oceans would have frozen from the bottom up and killed all the first life of the seas.
A fine day is rare enough even in the Cotswolds, and certainly it is not the default state of the world anywhere very much. If it is an accident that the earth is conducive to life it is only because of innumerable accidents. Innumerable accidents begin to look suspiciously like no accident at all.
What we don’t know is if these conditions, and many others, would rule out life, or only life as we currently understand it.
8 | The numbers game doesn’t work for life. With our best current measuring devices we are beginning to find other solar systems with proto-earths, and so the probability of there being life elsewhere goes up. But the probability also goes down, because we have not yet found life. On all the proto earths discovered so far the conditions are hellish. For as long as we do not find life elsewhere, what we find instead are the ever-finer conditions needed for life here. The more closely we investigate the conditions that did not result in life elsewhere, the more finely tuned those conditions become for life as it appeared here. There is no evidence that life is not a miracle; or, in scientific language, a very low probability event.1 How you answer the question: Is there life elsewhere? is a matter of taste.2
There is nothing that God hath established in a constant course of nature, and which therefore is done every day, but would seem a Miracle, and exercise our admiration, if it were done but once.
John Donne (1572–1631), metaphysical poet
9 | Science doesn’t do miracles: better to believe that there are many universes with many different conditions, and that we necessarily inhabit one island universe – ideally one of many island universes – in which the conditions for life are as they need to be.3
Science is the question, what does a world without the mediation of the supernatural look like?, repeated over and over again. If science were to accept irreducible mystery, or irreducible complexity, that would be to give up and admit defeat. Science moves into the unknown with the assumption that there is always something more that can be found out. To allow our universe special properties is one way of bringing scientific investigation to an end. To allow humans a privileged perspective is another. If humans have anything of the God-like about them they move beyond the reach of the scientific method. Instead, try to imagine a more encompassing universe in which the specialness disappears. And carry on. As science progresses, what the universe can be gets subtler and more mysterious. And as a by-product, the gods, God, and human beings become subtler too. If as scientists we were pragmatically to ignore what happens only once in the lifetime of the universe we would disavow ourselves and our planet home. Out of the scientific method, we humans never quite come into view. We can always look further out, but we humans seem always to be just over the horizon.
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