The concordance of physiological and pathological times in human identical twin pairs induced the authors to postulate the existence of a hereditary biological time.

Having formulated the hypothesis that the information of each gene has a given period of existence and that, therefore, every gene has its own inherited temporal dimension, the authors report on five different experimental studies intended to verify their hypothesis.

In the first study (cf II. 1) a twin research on bone age and dental age is performed. The chronological study of the appearance of ossification nuclei in carpal bones and of mineralization of the gems of permanent dentition, in 20 MZ and 20 DZ human twin pairs, indicates that these wellknown “biological timetables” exhibit about 70% of genotypical control.

In order to verify whether biological time is a function of the genotype as a whole, or a property of each individual gene, the authors carried out an experimental study on the mean lifespan in different strains of Drosophila melanogaster whose genotypes were fully known (cf II.2). Their results indicate that the specific information of certain genes controls the insect's lifespan; it may also be inferred that the differential persistence of its specific information is an attribute of each individual gene. This chronological dimension of the gene is called chronon, which the authors also define as “the period during which the original information of the gene remains unchanged” — whether it is used for transcription or duplication, or it remains at the potential stage.

The determination of alkaline phosphatase activity in the same strains of D. melanogaster (cf II.3) affords an estimate of the amount of genie information (intensity of the individual trait) and the variation thereof during the gene's chronon. The authors observe that the amount of information decreases gradually during the gene's chronon, suggesting that this be due to the gradual exhaustion of a given specific energy. The decrease in the amount of information in the longitudinal study of chronon leads the authors to identify a further fundamental parametric unit of the gene which they call ergon.

Ergon is defined as “the degree of stability of a gene”.

In the fourth study (cf II.4) the twin test is applied to the chromosome association index in subcultures of lymphocytes from MZ and DZ twins at age 6 and age 60. This study affords a parallel estimate of chronon (i.e., duration of information) and ergon (i.e., stability of information).

Chronon and ergon are found to be interrelated; they may be considered as variables in a dimensional equation of the gene. Thus, the existence of the Ergon/Chronon (E/C) system is postulated.

Nine parameters of development and of senescence (first smile, first word, first steps, first pubic hair, menarche, first white hair, first loss of a permanent tooth, first use of reading glasses, onset of menopause) are studied in an experimental population of 666 twin pairs of either zygosity, leading the authors to formulate several conclusions concerning the characteristics of the E/C system (cf II.5).

The interpretation of their experimental findings leads the authors to consider the ergon (energy of stability) of a gene as the total result of the stabilities of all the nucleotides making up the DNA sequence of that gene. Since it is well known that the stability of adenine-thymine (AT) bonds exceeds the stability of guanine-cytosine (GC) bonds, and that different combinations of codons (differing in at least one nucleotide) may provide the same information, it is clear that identical polypeptide chains may be produced under the control of genetically different ergons resulting in genetically different chronons.

The authors summarize these concepts in the following two aphorisms: “one gene, one stability” (ergon) and “one gene, one time” (chronon).

Biological time, development, senescence, homeostasis and disease are interpreted by the authors in the light of the E/C system.