# Prediction of the Maximum Temperature for Life Based on the Stability of Metabolites to Decomposition in Water

## TL;DR

This paper predicts the maximum temperature for life based on how stable metabolites are in water, suggesting life on Earth is limited to below 150–180°C.

## Contribution

The paper introduces a novel analytical framework to estimate the upper thermal limit for terrestrial life using metabolite decomposition rates.

## Key findings

- A preliminary analysis suggests terrestrial life is limited to temperatures below ~150–180°C due to metabolite instability.
- Decomposition rate constants for 63 metabolites were extracted and analyzed for thermal stability.
- Pressure is likely to have a minimal effect on the upper temperature limit for life.

## Abstract

The components of life must survive in a cell long enough to perform their function in that cell. Because the rate of attack by water increases with temperature, we can, in principle, predict a maximum temperature above which an active terrestrial metabolism cannot function by analysis of the decomposition rates of the components of life, and comparison of those rates with the metabolites’ minimum metabolic half-lives. The present study is a first step in this direction, providing an analytical framework and method, and analyzing the stability of 63 small molecule metabolites based on literature data. Assuming that attack by water follows a first order rate equation, we extracted decomposition rate constants from literature data and estimated their statistical reliability. The resulting rate equations were then used to give a measure of confidence in the half-life of the metabolite concerned at different temperatures. There is little reliable data on metabolite decomposition or hydrolysis rates in the literature, the data is mostly confined to a small number of classes of chemicals, and the data available are sometimes mutually contradictory because of varying reaction conditions. However, a preliminary analysis suggests that terrestrial biochemistry is limited to environments below ~150–180 °C. We comment briefly on why pressure is likely to have a small effect on this.