The Damage Done by Non-Standard Scientific Controls
To say that there is a lack of standardization in aging research is understating the matter. Pity the authors of reviews and meta-reviews, as they struggle to compare outcomes of animal studies between completely different, incompatible methodologies. Inconsistency in results is something of a feature even when different research groups attempt replication. The authors of this paper-length complaint focus down on one specific issue, the lack of standarization in the scientific control arm of a life span study, which is enough in and of itself to make comparison and replication challenging.
The search for interventions to slow down and even reverse aging is a burgeoning field. The literature cites hundreds of supposedly beneficial pharmacological and genetic interventions in model organisms: mice, rats, flies and worms, where research into physiology is routinely accompanied by lifespan data. Naturally the negative results are more frequent, yet scientifically quite valuable if analyzed systematically. Yet, there is a strong "discovery bias", i.e. results of interventions which turn out not to be beneficial remain unpublished.
Theoretically, all lifespan data is ripe for re-analysis: we could contrast the molecular targets and pathways across studies and help focus the further search for interventions. Alas, the results of most longevity studies are difficult to compare. This is in part because there are no clear, universally accepted standards for conducting such experiments or even for reporting such data. The situation is worsened by the fact that the authors often do not describe experimental conditions completely. As a result, works on longevity make up a set of precedents, each of which might be interesting in its own right, yet incoherent and incomparable. Here we point out specific issues and propose solutions for quality control by checking both inter-study and intra-study consistency of lifespan data.