An international team of scientists from Trinity College Dublin has discovered a fundamental pattern describing how any living organism responds to changes in temperature. Whether it is a bacterium, plant, insect, or mammal, biological “performance” follows the same mathematical curve. The study was published in the journal Proceedings of the National Academy of Sciences (PNAS).

What a temperature–performance curve is

Scientists have long known that temperature is one of the main factors determining the speed of biological processes—from cell division and growth to movement and reproduction.

To describe this relationship, researchers use temperature–performance curves: graphs where the X-axis represents temperature and the Y-axis represents some measure of organism activity, such as metabolic rate, heart rate, or running speed.

Until now, it was believed that the shape of these curves varied significantly between species. However, analysis of more than 2,500 curves collected from different studies showed the opposite: despite enormous differences among organisms, the curves have almost the same shape.

The universal temperature–performance curve

The researchers call the discovery a universal temperature–performance curve. Its pattern is simple yet dramatic:

  • at low temperatures, biological activity is almost zero
  • as temperature rises, performance gradually increases and reaches a peak—the optimal temperature
  • after the peak, activity drops sharply and eventually falls to zero at a critical temperature

The optimal temperature varies widely among species—from about +5 °C in some deep-sea bacteria to +100 °C in thermophilic archaea. However, the shape of the curve itself remains unchanged.

“Evolution has only been able to shift this curve along the temperature scale, but not alter its fundamental geometry,” the authors emphasize.

The link between optimal temperature and survival limits

Another key observation is that the optimal temperature and the lethal temperature (where the organism dies) are closely connected.

The higher the optimal temperature, the narrower the survival window above it becomes. In species adapted to high temperatures—such as thermophiles—even a small increase beyond the optimum can quickly lead to death.

This helps explain why organisms adapted to heat can sometimes be especially vulnerable to overheating.

Implications for understanding global warming

The discovery has direct relevance for the climate crisis. If all living organisms are constrained by the same universal curve, their ability to adapt to rapid temperature increases may be much more limited than previously thought.

Species with low optimal temperatures—which include many organisms in modern ecosystems—could enter the steep decline zone of the curve with temperature increases of only a few degrees.

Lead author Nicholas Payne noted that the study covered a wide range of life forms—from bacteria and plants to fish, reptiles, and insects—and all of them fit the same model.

What comes next

Scientists plan to use the universal curve as a benchmark and search for exceptions—organisms that deviate from the rule.

Such cases could reveal how life adapts to extreme environmental changes and which biological mechanisms might help species survive in a warming world.

In brief

Researchers from Trinity College Dublin analyzed more than 2,500 temperature–performance curves and discovered a universal law: all organisms—from bacteria to animals—respond to temperature changes with the same curve shape. Activity increases toward an optimum and then drops sharply after it.

Evolution can only shift the curve along the temperature axis, not change its geometry. The finding places limits on how species can adapt to global warming and was published in Proceedings of the National Academy of Sciences.