Famine-related mortality in early life and accelerated life histories in nineteenth-century Belgium

Density-dependent and extrinsic mortality are predicted to accelerate reproductive maturation. The first 5 years of life is a proposed sensitive period for life-history regulation. This study examines the ways in which local mortality during this sensitive period was related to subsequent marriage timing in nineteenth-century Belgium (n women = 11 892; n men = 14 140). Local mortality during the sensitive period was inversely associated with age at first marriage for men and women controlling for literacy, occupational status, population growth and migration. Cox regression indicated decreased time to marriage for women (HR = 1.661, 95% CI: 1.542–1.789) and men (HR = 1.327, 95% CI: 1.238–1.422) from high mortality municipalities. Rising population growth rates were associated with earlier marriage for men and women. Migration in general was associated with later marriage for men and women. Consistent with life-history predictions, harsh ecological conditions during early life such as famine coincided with earlier marriage.     

Legacies in life histories

Complex life-histories are common in nature, have many importantbiological consequences, and are an important focal area forintegrative biology. For organisms with complex life-histories,a legacy is something handed down from an ancestor or previousstage, and can be genetic, nutritional/provisional, experiential,as well as the result of random chance and natural variationin the environment. As we learn more about complex life-histories,it becomes clear that legacies are inexorably linked in theshort- and long-term through ecology and evolution. Understandingthe consequences and drivers of life-history patterns can thereforeonly be understood by considering all types of legacies andintegrating legacies across the entire life cycle. Larry McEdwardwas a leader in the field of ecological physiology, and evolutionaryecology of marine invertebrate larvae with complex life-histories.Through his scientific work and publications, devotion to students,colleagues, family, and friends, Larry has left a lasting legacythat will impact the future development of the field of larvalecology and complex life-histories.     

A life in books

A note from the Reviews Editor. How are intellectual and personal lives shaped through encounters with books? In this first instalment of our new occasional special feature, Tim Ingold responds to our invitation to select the five key books that most influenced his thinking. His selections illustrate the diversity of ways in which books can become meaningful: sometimes condensing an existing train of thought; in moments of inspiration; nagging away in languages that draw us in despite, or because of, the partial ways we understand; sometimes as points of arrival, redescribing what we already feel we know; at others as moments of departure, in new possibilities realized or glimpsed; in disagreement as much as assent; in the exhilarating revelation of a fleeting moment of discovery, or in the gradual evolution of new ideas over years or even decades.     

Artificial life and living systems: Insight into artificial life and its implications in life science research

Advanced technology has made it possible to build machines and systems like robots, which are capable of making intelligent decisions. Robots capable of self-replication and perform human functions are also available. The current challenge is to design evolutionary systems with high complexity comparable to that of biological networks. This is proposed to be achieved by ALife (Artificial Life). Here, we describe the promises provided by ALife for life sciences.     

Energy problems in life evolution

Evolutionary aspects of bioenergetics are considered. These include the origin of the first organisms, UV-protection and the beginnings of anoxygenic photosynthesis, the electron donor problem of life and the appearance of oxygenic photosynthesis, oxygen danger and strategies of defense, and the role of oxygen in programmed cell death.Translated from Biokhimiya, Vol. 70, No. 2, 2005, pp. 302–307.Original Russian Text Copyright © 2005 by Samuilov.This revised version was published online in April 2005 with corrections to the post codes.     

Data clustering in life sciences

Clustering has a wide range of applications in life sciences and over the years has been used in many areas ranging from the analysis of clinical information, phylogeny, genomics, and proteomics. The primary goal of this article is to provide an overview of the various issues involved in clustering large biological datasets, describe the merits and underlying assumptions of some of the commonly used clustering approaches, and provide insights on how to cluster datasets arising in various areas within life sciences. We also provide a brief introduction to Cluto, a general purpose toolkit for clustering various datasets, with an emphasis on its applications to problems and analysis requirements within life sciences.     

Loss in life expectancy and gain in life years as measures of cancer impact

There are a broad range of survival-based metrics that are available to report from cancer survival studies, with varying advantages and disadvantages. A combination of metrics should be considered to improve comprehensibility and give a fuller understanding of the impact of cancer. In this article, we discuss the utility of loss in life expectancy and gain in life years as measures of cancer impact, and to quantify differences across population groups. These measures are simple to interpret, have a real-world meaning, and evaluate impact over a life-time horizon. We illustrate the use of the loss in life expectancy measures through a range of examples using data on women diagnosed with cancer in England. We use four different examples across a number of tumour types to illustrate different uses of the metrics, and highlight how they can be interpreted and used in practice in population-based oncology studies. Extensions of the measures conditional on survival to specific times after diagnosis can be used to give updated prognosis for cancer patients. Furthermore, we show how the measures can be used to understand the impact of population differences seen across patient groups. We believe that these under-used, and relatively easy to calculate, measures of overall impact can supplement reporting of cancer survival metrics and improve the comprehensibility compared to the metrics typically reported.     

Genomics in space life sciences

Since the early days of manned spaceflight, hazardous effects of the space environment on living organisms have been disputed. With the continuous manning of the International Space Station, the planned Chinese space station, and renewed interest in returning to the Moon and sending manned flights to Mars, identifying and addressing the potential outcomes of long-term space exposures is critically important.     

Dynamic heterogeneity in life histories

Longitudinal data on natural populations have been analysed using multistage models in which survival depends on reproductive stage, and individuals change stages according to a Markov chain. These models are special cases of stage-structured population models. We show that stage-structured models generate dynamic heterogeneity: life-history differences produced by stochastic stratum dynamics. We characterize dynamic heterogeneity in a range of species across taxa by properties of the Markov chain: the entropy, which describes the extent of heterogeneity, and the subdominant eigenvalue, which describes the persistence of reproductive success during the life of an individual. Trajectories of reproductive stage determine survivorship, and we analyse the variance in lifespan within and between trajectories of reproductive stage. We show how stage-structured models can be used to predict realized distributions of lifetime reproductive success. Dynamic heterogeneity contrasts with fixed heterogeneity: unobserved differences that generate variation between life histories. We show by an example that observed distributions of lifetime reproductive success are often consistent with the claim that little or no fixed heterogeneity influences this trait. We propose that dynamic heterogeneity provides a 'neutral' model for assessing the possible role of unobserved 'quality' differences between individuals. We discuss fitness for dynamic life histories, and the implications of dynamic heterogeneity for the evolution of life histories and senescence.     

Photo acoustic in life sciences

Photoacoustic (PA) measurements provide, by the very nature of the PA effect, the possibility to obtain information on the optical and thermal properties of samples. In addition they can yield information on the enthalpy changes and characteristic times involved in photo-induced processes as the acoustic signal in proportional to the heat produced following the absorption of the modulated excitation. In the study of optical properties the relative insensitivity to scattered light of the PA signal makes such measurement an attractive way to measure biological samples in vivo, or, at least, withpout the need to isolated the absorbing compounds. The dependence of the PA signal on the thermal properties of the sample is particularly useful when heterogeneous samples are studied. As a photocalorimetric method the technique shows considerable promise in the study of photo-biogenergetics, especially photosynthesis. Only in special cases can analytical applications of the method compete with fluorescence measurements (for detection), and with increasingly sophisticated optical transmission and reflectance techniques (for identification). However, the PA method may find important uses in fundamental research and in applied areas such as biomedicine and agricultural biochemistry.