Information is Specific to Life

Abstract

It is argued in Chap. 9 that information is specific to life. The concept of ‘semantic feedback loops’ is first introduced in order to explain the onset of living structures and their conservation. The basic fact is that certain proteins act as enzymes which catalyze the operations which are needed for their own synthesis: transcription of DNA into messenger or premessenger RNA, splicing out the introns (in the case of eukaryotic cells) and translation as operated by the ribosome, i.e., synthesizing proteins under the control of messenger RNA. This can be interpreted as a set of interwoven feedback loops which all involve the genetic ‘code’ (or mapping). This set of loops acts as a trap since, once closed, it keeps its structure. If any of its parts fails, however, the whole system ceases operating. We refer to it as ‘semantic’ because the genetic mapping consists of a set of semantic rules. Hence, the set of feedback loops implements the semantics which enables the assembly of proteins (and more generally of phenotypes) in terms of the information that DNA bears. This shows how information, as an abstract fundamental entity, controls the assembly of physical structures. ‘Abstract’ should be understood here as opposed to physical, since assuming that information is physical leads to results which contradict its very definition. The set of semantic feedback loops, although each loop is closed, does not prevent the lengthening of genomes by horizontal genetic transfer, hence is compatible with evolution. The last section of this chapter examines the achievements of Nature as an engineer and pleads for a collaboration of engineers and biologists.