Universal Relation for Life-span Energy Consumption in Living Organisms: Insights for the origin of ageing

TL;DR

This study reveals a universal relation for life-span energy consumption across diverse species, suggesting a common total number of respiration cycles that may underpin the biological aging process.

Contribution

It introduces a universal relation for life-span energy consumption applicable to about 300 species, indicating a constant number of respiration cycles per lifetime across all organisms.

Findings

Energy consumption per lifespan is nearly constant across species.

Most organisms deviate less than a factor of π from the relation.

Supports the hypothesis of a fixed number of respiration cycles influencing aging.

Abstract

Metabolic energy consumption has long been thought to play a major role in the aging process ({\it 1}). Across species, a gram of tissue on average expends about the same amount of energy during life-span ({\it 2}). Energy restriction has also been shown that increases maximum life-span ({\it 3}) and retards age-associated changes ({\it 4}). However, there are significant exceptions to a universal energy consumption during life-span, mainly coming from the inter-class comparison ({\it 5, 6}). Here we present a unique relation for life-span energy consumption, valid for $\sim$300 species representing all classes of living organisms, from unicellular ones to the largest mammals. The relation has an average scatter of only 0.3 dex, with 95\% ($\rm 2-\sigma$) of the organisms having departures less than a factor of $\pi$ from the relation, despite the $\sim$20 orders of magnitude difference in body mass, reducing any possible inter-class variation in the relation to only a geometrical factor. This result can be interpreted as supporting evidence for the existence of an approximately constant total number $\rm N_r \sim 10^8$ of respiration cycles per lifetime for all organisms, effectively predetermining the extension of life by the basic energetics of respiration, being an incentive for future studies that investigate the relation of such constant $\rm N_r$ cycles per lifetime with the production rates of free radicals and oxidants, which may give definite constraints on the origin of ageing.