Periodic Kingdom, A journey into the land of the chemical elements
P. W. Atkins:
But no region is more fecund than carbon. Carbon is a
particularly mediocre element, easygoing in the liaisons it forms. Unlike
fluorine, which is only a few regions to the east of it, carbon is not a
reactive prima donna. In chemistry as in life, this unpretentiousness has
rewards, and in its mediocre way carbon has established itself as king of the
Immediately to the south of carbon lies silicon. As is so often the case with the neighbors, it is an uneasily ambiguous adjacency. Like carbon, but to a lesser degree, silicon is capable of forming some of the long-chain molecules needed in any process as complex as life, but it has not achieved a life of its own. It may be a sleeper in this regard, however. Carbon’s principle products, living organisms, have struggled over a few billion years to establish mechanisms for the accumulation and dispersal of information (an austere distillation and definition of what we mean by “life”), and silicon has lain in wait. The recent alliance of two regions, in which carbon-based organisms have developed the use of silicon-based artifacts for information technology, has resulted the enslavement of silicon. However, such is the precocity of carbon’s organisms that they are steadily developing silicon’s latent powers, and one day silicon may well overturn the suzerainty of its northern neighbor and assume the dominant role. It certainly has long term potential, for its metabolism and replication need not be as messy as carbon’s. Here we may see one of the most subtle interplays of alliances anywhere in the kingdom, for silicon will not realize its potential without the burden of development being carried out by carbon. (P17)
Oxygen is so vital to organic life on earth today that where it is not available it must be supplied. We carry it beneath the sea in tanks; we conveyed it to the moon. We pump it into the moribund bodies to help them keep their grip on life. We squirt it by the ton into engines to enable them to burn their fuel. Oxygen is the essence of animation, and animation and purposeful locomotion normally cease in its absence. (P 7)
Invisible potency is not confined to oxygen. Its western neighbor, nitrogen, is also apparently without substance bust essential to life: much biological and industrial chemical activity is focused on its capture from the atmosphere, where it is found in extraordinary abundance. The capture of nitrogen is called its fixation, and nitrogen fixation is a process of vital importance on Earth – as vital as photosynthesis, the fixation carbon from atmospheric carbon dioxide. (P 8)
One salient characteristic of life is that it is not over in a flash, but involves the slow uncoiling and careful disposition of energy: a spot of energy here, another there, not a sudden deluge. Life is a controlled unwinding of energy. Phosphorus, in the form of adenosine triphosphate (APT), turns out to be a perfect vector for the subtle deployment of energy, and it is common to all living cells. (P 21)
The region of sulfur was also explored by nature --- in
nature’s serendipitous, purposeless, but effective way --- in an early
investigation of the opportunities for life. Nature discovered that in some
respects hydrogen sulfide (H2S), the analog of water (H2O), can be used by
organisms in much the same way as water is used in the process of
photosynthesis --- as a source of hydrogen. The great difference to note is
that when hydrogen is removed from a water molecule by a green plant, the
excrement is gaseous oxygen, which then mingles with the globally distributed
atmosphere. However, when hydrogen is removed from hydrogen sulfide in the
interior of a bacterium, the excrement is sulfur. Sulfur, being a solid, does
not waft away, so the colony of organisms has to develop a mode of survival
based on a gradually accumulating mound of its own sewage. We still mine those ancient mound of sulfur excrement from beneath the
Comments: The transition from sulfur to oxygen was a major pollution event in biological history, which destroyed most living systems at that time. This example shows the importance of dumping high entropy waste in ecological systems. Those who are able to dump the excrement of themselves effectively will prosper, often at a cost to others. This is the same to human beings in economic development. Many industrial facilities are built by rivers or near seaside so wastes can be diffused quickly. While the gains from the industrial output are more concentrated and harvested by the owners of the industrial facilities, the wastes are diffused and shared by many others. (Cite Lovelock, Margulis and Hardin’s works.)
Those survived the oxygen poisoning, however, evolved the ability to take advantage of oxygen’s low entropy state as its vital energy source.