little doubt that the first step in preparing the earth as a habitation for man must have been to clothe it with vegetation as a source of food for the animals which preceded him. The earth's earliest atmosphere was almost certainly not suited for the support of animal life of any kind on land, though the seas could do so. All animals which live on land must have free oxygen as a source of energy. This oxygen can be breathed (or taken in through the skin, as it is in insects) mixed with other gases such as hydrogen or nitrogen, for instance. It appears that in the earth's atmosphere, at the beginning, even after noxious gases had been removed chiefly by loss from the earth's gravitational field, the available oxygen was combined with carbon in the form of carbon dioxide. In order to free the oxygen, plants were created to perform this role by photosynthesis, taking in carbon dioxide and setting the oxygen free in the atmosphere again, converting the carbon into usable form. Since all flesh is grass (1 Peter 1:24) in the sense that all animal life depends upon plant life for energy, plant life had to precede animal life not only to make the atmosphere respirable for them but to supply them with food energy.
But the first plants obviously had to be able to survive without soil, since soil is composed of decayed vegetation. Once vegetation of such a kind had multiplied sufficiently to create humus, then higher forms of plant life more effective as sources of energy for animals ‹ and later for man ‹ could be created and planted. That God should create and plant is not strange, for this is what we are told He did with respect to the Garden of Eden (Genesis 2:8).
The course of events was, then, somewhat as follows. The rock at the surface of the earth was broken down into gravel and sand by the action of waves, wind, gravitational shock (i.e., falling and breaking), and by alternating heat and cold, which would fragment the rock by expansion and contraction. In addition, volcanic action
contributed ash and certain chemicals. In due time such combined forces provided suitable beds for the creation and planting of vegetation capable of growing without soil. As W. Bell Dawson pointed out, to begin the process of clothing the earth, God designed plants that could grow in pure sand; and these gradually made soil for plants of higher classes to grow in. There is, for example, one species of pine which is used extensively in France in the dunes along the coast, for the purpose of preventing them from drifting back over the cultivated fields.
These first plants were reeds, rushes, and ferns, and although they often grew as large as trees, they were not the kind of vegetation which higher forms of animals use as food. They served a dual purpose, however. While they lived, they began to remove from the atmosphere its excess carbon dioxide; and when they died, they created a humus which when it had accumulated sufficiently provided the bed into which higher forms of plant life were introduced by creation. Lichens also enter this picture as fundamental to all that followed. "Lichens have no need for soil, but, preparing it, they lay the cornerstone for flowers and trees. They are the plant world's pioneers, bringing life where none existed." When the time was fully come that animals should move out of the sea on to the dry land, there was both air fit for them to breathe and food suitable for them to eat.
George Wald, Professor of Biology at Harvard, speaks of the preparation of the atmosphere by plant life in the following way:
The atmosphere of our planet seems to have contained no (free) oxygen until organisms placed it there by the process of plant photosynthesis. . . .
Once this was available organisms could invent a new way to acquire energy, many times as efficient. . . This is the process of cold combustion called respiration.
Wald spoke of "inventing" a new way to acquire energy far more efficient than the methods by which plants acquire it. The word "invent" is inappropriate since it attributes to inanimate things a consciousness of purpose which they surely do not have. But his remarks serve to point out that the liberation of free oxygen for cellular respiration allowed for the introduction of living forms with immensely increased energy potential. The lowest, and thus presumably the oldest, deposits of minerals are found in non-oxidized form, which seems to demonstrate the initial absence of free oxygen. It is evident, therefore, that animal life could not have existed until the plants had transformed the atmosphere.
This step thus opened the way for the introduction of creatures which were far less tied to their environment, one further step in the unfolding of God's purposes in the ultimate creation of man. As Wald put it: (
Photosynthesis made organisms self-sustaining; coupled with respiration, it provided a surplus (of energy). To use an economic analogy, photosynthesis brought life to the subsistence level, respiration provided it with capital.But this is not all. The new atmosphere thus generated had an equally important function of another kind:
The entry of oxygen into the atmosphere also liberated organisms in another sense. The sun's radiation contains ultraviolet components which no living cell can tolerate. We are sometimes told that if this radiation were to reach the earth's surface, life would cease. That is not quite true. Water absorbs ultraviolet radiation very effectively, and one must conclude that as long as these rays penetrated in quantity to the surface of the earth, life had to remain under water.These stages of preparation reinforce the concept of purpose, because they indicate the timed introduction of the requisite elements in the economy of Nature at each step as required -- and very frequently without predecessors. The appearance of lichens, for example, looks much more like deliberate creation than the outcome of pure chance. Similarly, later on, lungs seemed to be in the making at the same time that the atmosphere was being prepared for creatures that could make full use of such structures, a circumstance which again looks much more like planning than the operation of pure chance.
With the appearance of oxygen, however, a layer of ozone formed high in the atmosphere and absorbed this radiation. Now organisms could for the first time emerge from the water and begin to populate the earth and the air. Oxygen provided not only the means of obtaining adequate energy for evolution, but the protective blanket of ozone which alone made possible terrestrial life.
Everything is orderly and purposeful, there is nothing accidental about the order in which forms of life appear from amoeba to man. Next time we'll take up the discussion of
To be continued . . .