A hidden temperature law governs all life on Earth

The Hidden Pattern Linking All Species

Temperature affects every form of life, but the UTPC connects what once seemed to be countless unrelated data sets. It combines tens of thousands of performance curves that describe how efficiently species function at different temperatures. The researchers found that this universal pattern applies not just to all organisms, but also to all kinds of performance metrics -- whether measuring lizards sprinting on a treadmill, sharks swimming in open water, or bacteria dividing under a microscope.

Rising Heat and Falling Performance

The study revealed a consistent trend in how organisms respond to warmth:

• Performance increases gradually as temperature rises until reaching a peak (the optimum point).
• Beyond this optimum, performance drops sharply.
• When temperatures climb too high, overheating can cause physiological breakdown or death.

These findings, published in the journal PNAS, suggest that species may face greater limits than previously thought when adapting to global climate change. As most regions continue to warm, the window of viable performance for many species could shrink.

One Curve, Many Temperatures

Andrew Jackson, Professor in Zoology in Trinity's School of Natural Sciences, and co-author,said: "Across thousands of species and almost all groups of life including bacteria, plants, reptiles, fish and insects, the shape of the curve that describes how performance changes with temperature is very similar. However, different species have very different optimal temperatures, ranging from 5^oC to 100^oC, and their performance can vary a lot depending on the measure of performance being observed and the species in question."

"That has led to countless variations on models being proposed to explain these differences. What we have shown here is that all the different curves are in fact the same exact curve, just stretched and shifted over different temperatures. And what's more, we have shown that the optimal temperature and the critical maximum temperature at which death occurs are inextricably linked."

"Whatever the species, it simply must have a smaller temperature range at which life is viable once temperatures shift above the optimum."

The Unbreakable Law of Thermal Performance

Senior author, Dr. Nicholas Payne, from Trinity's School of Natural Sciences, added: "These results have sprung forward from an in-depth analysis of over 2,500 different thermal performance curves, which comprise a tremendous variety of different performance measures for a similarly tremendous variety of different species -- from bacteria to plants, and from lizards to insects."

"This means the pattern holds for species in all major groups that have diverged massively as the tree of life has grown throughout billions of years of evolution. Despite this rich diversity of life, our study shows basically all life forms remain remarkably constrained by this 'rule' on how temperature influences their ability to function. The best evolution has managed is to move this curve around -- life hasn't found a way to deviate from this one very specific thermal performance shape."

Searching for the Exceptions

"The next step is to use this model as something of a benchmark to see if there are any species or systems we can find that may, subtly, break away from this pattern. If we find any, we will be excited to ask why and how they do it -- especially given forecasts of how our climate is likely to keep warming in the next decades."