Why Is the Cell So Complex

It is useful to compare the complexity of the living cell with that of the atom. If the complexity of a physical system is expressed in terms of the algorithmic information content (defined as the number of words or bits needed to describe a system; see Sect. 4.3) and if we assume that the algorithmic information content of a system is approximately proportional to its volume, the complexity of the average cell would be about 1015 times that of the hydrogen atom (see Table 10.3). Think of the number of the articles (and the words or symbols in them) that have been published describing the essential features of the hydrogen atom, which can be easily in the hundreds. Then the number of the papers that would be needed to describe the essential features of the living cell could well reach 1017, a number equivalent to about a million papers written per person now living on this planet! This is probably why there are so many biological papers published every week in Science, prompting nonbiological scientists (such as one of my professors in chemistry at the University of Minnesota, Duluth, in the mid-1960s) to complain in effect that there are too many biological articles in Science. The situation is far worse now than it was a half century ago. As will become evident below, one simple answer to the title suggested by the Law of Requisite Variety (Sect. 5.3) is that the internal structure of the cell has to be complex in order to survive the environment that is at least as complex.