Resources were scant. These studies further support the notion that variation in living organisms is

Resources were scant. These studies further support the notion that variation in living organisms is a force capable of permitting individual fine-tuning to a changing environment and thereby contributing to survival and reproduction. Ultimately, these examples indicate that variation is a norm and that it may exert a pivotal evolutionary-adaptive function. Importantly, the experimental evidence in support of this fundamental evolutionary adaptive mechanism stems from converging studies of three different species (neither rats nor mice), and adopting completely different methodologies. By the same token, since these mechanisms generalize to a wide range of tax a, they should also pertain to laboratory rodents. Thus, should neonatal rearing conditions provide laboratory rodents with information about their future habitat, it is tenable to question the extent to which our husbandry strategies favour adaptive plasticity to the lab specific challenges encountered by experimental rats and mice.Are laboratory rodents adapted to their living and testing conditions?In the previous paragraph, we described experimental evidence indicating that environmental cues encountered during the early stages of development adaptivelycalibrate individual adjustments to adult life conditions [21,24,27]. We also reported evidence indicating that situations in which neonatal pretences do not match adult life conditions may favour vulnerability to pathology [31,32]. Since rats and mice are daily used as models for human function and dysfunction, we may wonder whether their neonatal life conditions match the challenges encountered in adulthood (thereby favouring adaptive plasticity) or whether they are not adequate predictors thereby hampering “normal” development. The consequence of this question is: can control rats and mice be regarded as “normal” individuals? The fact that neonatal life conditions in laboratory facilities do not adequately reflect adult challenges has already been discussed in details [34]. Such proposition rested upon the observation that, while neonatal conditions are pervaded by safety, stability and quietness, adult challenges to a laboratory rodent can occur frequently and in variable ways. For example, single housing, re-grouping, injections, food PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/27872238 shortage/deprivation, and cage tilting constitute a subset of stressors present in the daily life of a laboratory individual. Thus, the precocious quietness has been proposed to conflict with the adult life encountered by experimental subjects [34]. To evaluate whether plastic adjustments to neonatal rearing conditions affected the quality of experimental data, we devised a strategy to address the extent to which laboratory animals approximate a “normal” population [35], wherein “GW9662 web normality” has to be considered in statistical terms (Gaussian distribution). Previous studies proposed that while physiological variables should distribute normally in a natural population, the elevated occurrence of abnormal behaviours (due to captivity) may skew data distribution [36]. Resting upon these propositions, we first addressed the data distribution of a large set of data collected in control mice, and then evaluated whether exposing neonate subjects to physiological stressors may favour the exhibition of normal behaviour [35]. The rationale behind this study was the following: (i) laboratory animals are reared under highly stable and safe conditions; (ii) adult life conditions do not match neonatal expect.