"Needs," "pleasures," or both? Operationalizing "environmental enrichments" in terms of their impacts on animal welfare and other aspects of biological functioning

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My group works on the objective assessment of animal welfare & the impact of impoverished housing, with a view to the evidence-based improvement of farm, laboratory & zoo animal well-being. This 5-year program tackles 'environmental enrichment': the adding of complexity &/or opportunities for natural behaviour to barren, unstimulating cages. It aims to formalise how environmental enrichments are defined & categorised, by improving the understanding of their many potential benefits on animals' functioning. Thus to animal welfare scientists, successful enrichments improve welfare - but they can do this in different ways (ways empirically teased apart by carefully combining different research approaches): they may alleviate chronic stress by meet- ing animals' needs for particular resources or activities, or, perhaps less importantly, they may just elicit posit- ive emotions or 'pleasure'. (Some enrichments may even have both types of property, turning from 'Pleasures' into 'Needs' if experience leads to dependency). To neuroscientists, in contrast, successful enrichments cause improvements in brain structure & function. A vast literature exists on this; but despite intriguing evidence that positive emotions and/or stress reduction may mediate such effects, the hypothesis that enrichments enhance animals' brain development by improving their wellbeing has never been tested. Other types of study are start- ing to reveal yet more longterm benefits of enrichment. Some enhance animals' abilities to reproduce; others allow them to live longer. Stress reduction is a plausible explanation; human data even suggest that being happy (not just 'not stressed') improves lifespan. Yet once again, whether wellbeing enhances fitness, & quite how it may do so, is not fully resolved. Through a series of focussed experiments on mink & mice, we will build a substantial database on the motivational & stress-reducing properties of over 20 different enrichments, allowing us to statistically investigate how such effects relate to (even cause) enhanced brain development, reproductive success & lifespan. The most comprehensive screening of enrichments ever conducted, this research has considerable implications for the assessment & improvement of captive animals' welfare.