Both life history theory and demographic transition theory predict that fertility responds to changes in mortality, but there have been relatively few tests which identify links between mortality perceptions and fertility preferences at the individual level. This paper provides an individual-level investigation of the relationship between mortality and fertility, by testing whether mortality priming results in an increase in fertility preferences. Data were collected via an internet-based experiment of students at the London School of Economics (LSE), who were randomly allocated between two questionnaires. The treatment questionnaire asked a set of mortality priming questions and then collected information on fertility preferences and attitudes towards the costs and benefits of children. The control questionnaire recorded information on fertility preferences without prior mortality priming. The results suggest that mortality priming resulted in higher ideal number of children for males, but not for females. There were no significant differences in the attitudes towards the costs and benefits of children for either sex, though the raw data suggest a slight shift towards viewing children as less costly after mortality-priming, particularly for men. This paper therefore argues that the reaction of fertility to mortality may be at least partly mediated by a direct psychological link between mortality perceptions and reproductive behaviour.

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Particular features of human female life history, such as short birth intervals and the early cessation of female reproduction (menopause), are argued to be evidence that humans are ‘cooperative breeders’, with a reproductive strategy adapted to conditions where mothers receive substantial assistance in childraising. Evolutionary anthropologists have so far largely focussed on measuring the influence of kin on reproduction in natural fertility populations. Here we look at the effect in a present-day low-fertility population, by analysing whether kin affect parity progression in the British Household Panel Study. Two explanatory variables related to kin influence significantly increase the odds of a female having a second birth: i) having relatives who provide childcare and ii) having a larger number of frequently contacted and emotionally close relatives. Both effects were measured subject to numerous socio-economic controls and appear to be independent of one another. We therefore conclude that kin may influence the progression to a second birth. This influence is possibly due to two proximate mechanisms: kin priming through communication and kin assistance with childcare.