The pace and shape of ageing

Abstract

Summary 1. Humans age, but how much more or less do we age compared with other species? Do humans age more than chimps, birds more than fish or sheep more than buffalos? In this article, I argue that current methods to compare patterns of ageing across species are limited because they confound two dimensions of age‐specific change – the pace and the shape of ageing. 2. Based on the two axes of pace and shape, I introduce a new conceptual framework to classify how species age. 3. With this method, I rank species according to how strongly they age (shape) and how fast they age (pace). Depending on whether they are ranked by pace or by shape, species are ordered differently. 4. Alternative pace measures turn out to be highly correlated. Alternative shape measures are also highly correlated. The correlation between pace and shape ranking is negative but weak. Among the examples here, no species is long lived yet exhibits negligible ageing – contrary to the commonly held view that long‐lived species are good candidates for negligible ageing. 5. Analysis of species in pace–shape space provides a tool to identify key determinants of the evolution of ageing for species across the tree of life.

Human mortality improvement in evolutionary context

“…Although the human life history has many unique features (30), our underlying biological potential for plasticity in mortality is likely to be shared with other taxa. That said, there are likely taxonomic differences in the shapes of mortality profiles (31), the age at lowest mortality, and the lowest mortality level (if any) that a species can achieve. Research is needed on identifying what those taxonomic signatures may be.…”

Age and time-to-death trajectories of change in indicators of cognitive, sensory, physical, health, social, and self-related functions.

“…Furthermore, the modeling approach used in this study could be complemented by models that combine longitudinal growth curve modeling with survival analyses to estimate the influence that level and change in the constructs of interest have on age at death (e.g., Ghisletta, McArdle, & Lindenberger, 2006). Finally, inspired by work in neighboring disciplines (e.g., Baudisch, 2011), it may be worthwhile to fit models of aging and mortality risk that are nonlinear in the parameters (e.g., exponential decline functions). More generally, articulating and testing multidimensional notions of late-life change will expand the theoretical framework from which terminal decline has been studied and provide an integrated picture of how and potential reasons why some individuals age more successfully than others (e.g., experience less decline prior to death).…”

Earlier and more rapid ageing: Does nutrition contribute?

“…More systematic statistical information can be found almost everywhere, for instance in the HMD (Human Mortality Database), which also happens to be the source of data for our analysis. However, the connection between longevity and physiological ageing is elusive and the two concepts are not synonymous (Baudisch, 2011;Baudisch and Vaupel, 2012). Biologists and gerontologists interpret ageing (or senescence) as the process by which molecular damage increases at the cellular level (Rattan, 2006;.…”