Human Reproductive Costs and the Predicted Response to Dietary Restriction

Abstract

The question has arisen in the literature as to whether dietary restriction (DR) will have a significant effect on human longevity. I initially use literature data to estimate the energy costs necessary to carry a human from conception to caloric self-sufficiency to be approximately 12.6 x 10(6)kcal, which amounts to approximately 25% of the the two parents' combined daily caloric intake for 20 years. Similar levels of financial costs are expended in developed societies. Thus, human reproductive costs are high enough to permit a DR response. I then review four different models relating diet and life span, three of which have been previously used to estimate the effects of DR on humans. A review of the pertinent literature suggests that these three models, while plausible, are not capable of making robust predictions that are consistent with human data not used in their development. Given this weakness, none of the predictions made by these theories should be relied on for policy development at this time. The fourth, or biocultural model, examined combines biologic and cultural factors. Human longevity is more complex than our model systems have led us to believe, and thus any solution will require the development of a new quantitative model. The outlines of a suggested quantitative biocultural model based on the prior model of Crews and the disposable soma model of Shanley and Kirkwood are presented and a prediction of the possible data outcomes is made. If the human cultural pro-longevity practices can be quantified in terms of their effect on energy allocation, then this model may serve in future as a realistic quantitative model capable of identifying pertinent pathways and making robust predictions.

The Current Obesity Epidemic: Unravelling the Evolutionary Legacy of Adipose Tissue

“…Arking [24] has calculated that the energy cost necessary to carry a human from conception to caloric self-sufficiency is approximately 12.6 x 10 6 Kcal, which represents 25 % of the two parents daily caloric intake for 20 years. More concretely, pregnancy cost has been estimated at around 80 000 kcal [1].…”

Why and How We Age, and Is That Process Modifiable?

“…A recent theoretical analysis of this question indicates that it costs each human parent about 25% of their mean daily caloric intake (or a comparable amount of their cash income) to raise a human from conception to the age of caloric self-sufficiency (∼20 years). 22) The total caloric costs of this feat are about 12.6 × 10 6 kcals for each child, not including premature deaths. In modern terms, the minimum financial costs are about 25% of each parent's income per child, or a minimum estimate of US$191,000 per child excluding college expenses.…”

“…[Omitted from this figure for clarity is the developmental stage which precedes the health span and which in humans comprises the time period from birth to s 18-20 years. 22) Also omitted is the resource sharing that transfers energy and information from the health and senescent stages to the development phase, as well as energy from the health phase to the senescent phase, and information from the senescent phase to the health phase. Every generation is a sandwich generation.]…”