In discussing the origin of life upon the earth, we of the twentieth century must recognise such facts as may be obtainable in regard to life upon other orbs than ours. Now, in the first place, there is at least one illustrious contemporary astronomer, Professor Pickering, the chief living student of the moon, in whose opinion there are many evidences upon our satellite of the action of vegetation, either past or present. This, of course, is not the place for a discussion of that evidence; it is, however, the place to record the most highly qualified opinion at present obtainable, and to remind ourselves of the certainty that when the moon was first borne—or born—from the earth, life cannot possibly have been evolved, since the conditions of temperature alone, to name one factor, were such as life could not sustain, no liquid water being extant. There is some reason to suppose, then, that, whatever the present case may be, life was at one time spontaneously evolved upon the moon.
The second piece of astronomical evidence relevant to our inquiry is afforded by the planet Mars. This, of course, is a much controverted question, which cannot receive any discussion here. It suffices to note that Professor Lowell, who is admittedly the greatest living authority on Mars, has observed and photographed, not merely to his own satisfaction, but to that of an ever increasing number of astronomers, signs of vegetation upon Mars. I will say nothing here as to the existence of intelligent beings there. That fascinating and momentous question, upon which there will doubtless be difference of opinion for some time to come, does not now concern us. It is of quite sufficient significance for our present purpose if the existence of merely vegetable life, and no more, upon the planet Mars can be demonstrated, and there are now very few astronomers indeed who question this demonstration, however chary they may be of going any further. I submit that the question of the beginning of life upon the earth should not be considered without reference to the evidence which suggests the spontaneous origin of life upon the moon, and to the practically positive demonstration of the present existence, with seasonal alternations, as on our own earth, of vegetable life in the watered areas of Mars.
The Earth’s Crumbling “Foundations”
These considerations were entirely unknown to the great controversialists of a generation ago; but there is another order of facts, entirely unimagined by them, which are now demonstrable and admitted. For them, or for most of them, the ancient conception of matter which we trace to Plato was substantially true; nay, more. The recent work of the physicists and chemists had endowed that ancient conception of matter as gross and inert and dead with a new concreteness and vividness. One of the greatest physicists of the age, James Clerk-Maxwell, in his famous address to the British Association, spoke of atoms as the “foundation stones of the visible universe, which have existed since the creation unbroken and unworn.” The accepted conception of an atom was that of a passive thing; it had its own inherent shape and properties, which were impressed upon it at its creation. It had “the stamp of the manufactured article,” as Sir John Herschell said, and throughout its endless history it responded to and behaved under the influence of external forces in due accordance with its shape and size. But it was unchangeable, inert and brute, the sport of its surroundings, like the mote in the sun-beam.
Immeasurable Ocean of Energy
But to-day we stand amazed at such conceptions. We have learnt that within the atoms of matter there is a fund of energy so incalculably vast that the sum total of all the energies previously recognised, and now to be styled extra-atomic, is as nothing compared with it. This is a change indeed, that all the energies hitherto known to us should be merely the overflow trickling from the immeasurable ocean of the intra-atomic energy, the very existence of which has been formally and repeatedly denied by practically all thinkers from Plato down to our own time. Matter is not gross and inert, brute and dead. The atom, the so-called unchangeable foundation stone, is, on the contrary, itself an organism, the theatre of Titanic forces about which we at present know practically nothing except that they certainly exist, and are powerful beyond all our previous conceptions. The atom is no atom, but a microcosm; it is no more the unit of inorganic matter than the cell is really the unit of living matter.
Now it is surely evident on consideration, though the significance of the change has been ignored, that the whole discussion of the spontaneous origin or evolution of life in matter takes an entirely new shape when our old and widely erroneous conception of matter is abandoned, and a true one is substituted. Life is a marvellous and characteristic demonstration of energy. When the origin of this energy in matter was formerly discussed, we were told that the constituent parts of matter contain no energy at all, but now we know that a quite overwhelming proportion of the sum total of universal energy is to be found there, and nowhere else. This is one of the most revolutionary advances in the whole history of thought, and its full significance has yet to be recognised.
There must also be added an essential to any future discussion of this question, the extraordinary achievement of synthetic chemistry, of which Professor Berthelot was the grand master. As long ago as 1828 it was shown that there was at least one exception to the doctrine of the vitalists, that chemical compounds characteristic of living matter cannot be built up except by the living organism. To-day chemistry has succeeded in building up alcohols, starches, sugars, and even the forerunners of the proteids themselves, from the inorganic elements in the laboratory, under the action of non-vital forces. This fact could not be reckoned with a generation ago.
Can Chemistry Build Up Life?
We are now entitled to state very briefly the sequence of events which may reasonably be imagined as culminating in the origin of life upon the earth for the first time. Whatever we may hold as to the present, we have to recognise that the origin of life for the first time constituted a fact utterly different in certain essentials from any origin of life that may be expected to be occurring to-day. The capital fact is that in the beginning there was no organic matter to serve as food material. If ever there was a case in which it is the first step that costs, it is here. Nothing can be easier than to imagine the spontaneous origin of life in organic matter to-day, favoured with sun and water and air. The case is far different when a primary origin in inorganic matter has to be conceived. But of some things we are certain. We are certain, for instance, that so long as the earth’s surface temperature was above that of boiling water, no life was possible. It was not until the gaseous water in the atmosphere became liquefied by the lowering of the earth’s temperature that the production of life became possible. The first seas were seas of boiling water, or rather water infinitesimally below the boiling point, and we may reasonably suppose, with Buffon, that the Polar seas, being the first to cool, must have provided the first “nest” for life upon the earth. I assume, of course, that this essay will be read in conjunction with that of Professor Sollas upon the formation of the earth [[page 79]], and that of Dr. Wallace upon the exquisite adaptation between life and the earth to-day [[page 91]].