ABSTRACT
The thing which is most striking as a contemporary gerontologist looking back at the literature from the beginnings of the field is the complete absence of any organizing theoretical principles which would allow investigators to gain understanding (rather than simply experimental results) from the systems they chose to study. There seems to have been little consensus on what the ageing process actually was and this rendered discussion of any subsequent questions turbid to say the least. Some years before, Strehler (Strehler and Mildvan, 1960) had set out four principle criteria that defined the ageing process (or at least distinguished it from maturation and development) but there is little evidence from the 1967 SEB symposium that these were enthusiastically embraced by his contemporaries. Strehler defined ageing as a process which was:
• Universal (i.e. all members of a population of organisms will show it, a distinction from infectious disease);
• Progressive (the process was continual and incremental rather than sudden as in the case of ‘programmed’ organismal death);
• Intrinsic (distinguishing ageing from death due to outside events); • Degenerative (this captures the idea that ageing is associated with both increasing
chances of mortality but also an increasing level of morbidity).
