Interest in incorporating life history research from evolutionary biology into the human sciences has grown rapidly in recent years. Two core features of this research have the potential to prove valuable in strengthening theoretical frameworks in the health and social sciences: the idea that these is a fundamental trade-off between reproduction and health; and that environmental influences are important in determining individual life histories. For example, the idea that mortality risk in the environment shifts individuals along a ‘fast-slow continuum’ of ‘life history strategy’ is now popular in the evolutionary human sciences. In biology, ‘fast’ life history strategists prioritise reproduction over health so that individuals grow quickly, reproduce early and often, and suffer a rapid deterioration in health and relatively early death; ‘slow’ strategists start reproducing later, have fewer offspring, and die at an older age. Evolutionary human scientists tend to assume that, along with these life history outcomes, several behavioural traits, such as parenting, mating and risk-taking behaviour and, in the most expansive version, a whole suite of psychological and personality traits also cluster together into ‘fast’ and ‘slow’ life histories. Here, I review the different approaches to life history strategies from evolutionary anthropologists, developmental psychologists and evolutionary psychologists, in order to assess the theoretical and empirical evidence for human ‘life history strategies’. While there is precedent in biology for the argument that some behavioural traits, notably risk-taking behaviour, may be linked in predictable ways with life history outcomes, there is relatively little theoretical or empirical justification for including a very wide range of behavioural traits in a ‘life history strategy’. Given the diversity and lack of consistency in this human life history literature, I then make recommendations for improving its usefulness: 1) greater clarity over terminology, so that a distinction is made between life history outcomes such as age at maturity, first birth and death, and behavioural traits which may be associated with life history outcomes but are not life history traits themselves; 2) more empirical data on linkages between life history traits, behavioural traits and the environment, including the underlying mechanisms which generate these linkages; 3) more empirical work on life history strategies in a much broader range of populations than has so far been studied. Such a research programme on human life history has the potential to produce valuable insights for the health and social sciences, not least because of its interest in environmental influences on health, reproduction and behaviour.
Morph-specific differences in life history traits between the winged and wingless morphs of the aphid, Sitobion avenae (Fabricius) (Hemiptera: Aphididae)
