Ageing is not just a linear physiological decline (see L. Fontana et al. Nature 511, 405–407; 2014). Research into its more positive features could lead to a better-quality and longer life.

Personal resources such as optimism, resilience and engagement are integral to ageing well (see, for example, T. D. Cosco et al. BMJ Open 3, e002710; 2013).

Investigating the contribution of psychosocial strengths to positive ageing in human models would provide further insight into, and complement, physiological animal models.