The Complexity of Biological Ageing

The present review deals with the computer simulation of biological ageing as well as its demographic consequences for industrialized societies.Comment: For Fractal 2004 proceedings, Vancouver; 12 pages of review including 6 fig

Old age mortality : a state of the art

This Phd research report aims to obtain a better understanding of the recent changes in mortality of the elderly population in developed countries. It's essence will be a critical thinking, without performing empirical work, which means that the analysis and concepts of the actual demographic literature will form the main body of this work. There are two central questions: Which age and cause specific mortality trends caused these recent changes in the life expectancy?Did the increase in life expectancy of the elderly population accelerate, continue or decline in recent years?"Aquesta memòria de recerca de doctorat té com a objectiu obtenir una millor comprensió dels recents canvis de mortalitat de la població més vella en els països desenvolupats. L'essència d'aquest treball és més bé teòric que empíric, per tant l'anàlisis i conceptes de la recent literatura demogràfica formaran el cos principal d'aquest treball. Hi ha dues qüestions principals: Quines edats i causes de mort provoquen aquests canvis recents de l'esperança de vida ? L 'augment de l' esperança de vida de la població més vella s' accelera, accelerar, es manté o disminueixr en aquests darrers anys

Modelling the development of world records in running

We model the development of world records of metric running events from the 100 meter dash to the marathon for men and women. First, we review methods to fit time-series curves of world records in general. We discuss methods to estimate curves and review candidate functional forms that fit the systematic shape of the progress of world records. Next, we fit the asymmetric Gompertz-curves for 16 events and compute implied limit values. In order to assess the implied limits we use the Francis (1943)-model to relate limit records and distance in a log-log specification. We compare men and women and conclude that there is a fixed difference in record times between the two sexes. Finally, using the log-log relationship between time and distance we calculate the development of the world record of the mile in a robustness check.

Optimal Aging and Death: Understanding the Preston Curve

The present study examines whether the Preston curve reflects a causal impact of income on longevity or, for example, factors correlated with both income and life expectancy. In order to understand the Preston curve better, we develop a model of optimal intertemporal consumption in which the representative consumer is subject to physiological aging. In modeling aging we draw on recent research in the fields of biology and medicine. The speed of the aging process, and thus the time of death, are endogenously determined by optimal health investments. We calibrate the model to US data and proceed to show that the model accounts for nearly 80% of the cross-country differences in life expectancy that the Preston curve captures.aging; longevity; health investments; savings; Preston curve

Mechanics of Phenotypic Aging Trajectories in C. elegans and Humans

Overall, my dissertation integrates longitudinal measurements of physiology to investigate the aging process. In the first half, I examine the surprising and largely unexplained degree of variation in lifespan within even homogeneous populations. I sought to understand how physiological aging differs between long- and short-lived individuals within a population of genetically identical C. elegans reared in a homogeneous environment. Using a novel culture apparatus, I longitudinally monitored aspects of aging physiology across a large population of isolated individuals. Aggregating several measures into an overall estimate of senescence, I find that long- and short-lived individuals start adulthood on an equal physiological footing. However, longer-lived individuals then experience slower declines in function, but spend a disproportionately large portion of life in poor physiological health. Indeed, the period of early-life good health is much less variable than the period of late-life advanced senescence, which I conclude to be a more plastic phase of life. In the second half, I show that simple physiological measurements have broader lifespan-predictive value than previously believed and that incorporating information from multiple time points can significantly increase that predictive capacity. Using longitudinal data from a cohort of 1349 human participants in the Framingham Heart Study, I show that as early as 28–38 years of age, almost 10% of variation in future lifespan can be predicted from simple clinical parameters. Further, different clinical measurements are predictive of lifespan in different age regimes. Moreover, I find that several blood glucose and blood pressure are best considered as measures of a rate of “damage accrual”, such that total historical exposure, rather than current measurement values, is the most relevant risk factor (as with pack-years of cigarette smoking). Together, this work has established the physiological basis of variation in longevity within an isogenic population of C. elegans and extended our ability to predict mortality from basic clinical measurements in humans