ABSTRACT:

Temperature plays a crucial role across all scales of biological organization: from enzymatic reactions to cellular processes, from organismal behavior to ecosystem dynamics. Understanding and predicting temperature dependencies in biology has become increasingly urgent in light of the ongoing climate crisis in which environmental temperatures are rapidly changing. Yet, a unifying mechanistic framework that predicts temperature dependence across biological scales is still lacking. 

In contrast, for elementary chemical reactions, rates are well-described by the Arrhenius equation, which is rooted in transition-state theory. Remarkably, over the past century it has repeatedly been found that the Arrhenius equation also provides a good empirical fit to biological rates and timings (e.g., the utility of the constant Q10 approximation). This is surprising, given that macroscopic biological rates emerge from vast networks of chemical reactions whose temperature sensitivities may all differ substantially. At the same time, this empirical practice of fitting Arrhenius-like laws to biological rates, has also revealed systematic deviations at temperature extremes.  

Drawing on experimental examples from complex chemical oscillators, the cell cycle and embryonal development, and using the tools from dynamical systems theory and stochastic Markov processes, we explain: 

1. why the Arrhenius equation, originally developed in the context of chemistry, is often still a reasonable approximation at biological scales
2. how deviations from Arrhenius scaling at the macroscopic level can emerge from Arrhenius scaling at a microscopic level, and 
3. how deviations from the Arrhenius equation can point us to interesting biology.  

BIOSKETCH:

Simen began his academic studies with a bachelor’s in electrotechnical and material engineering before pursuing a bachelor’s and master’s in physics at KU Leuven. During his master years he focused on high-energy physics and completed a thesis on black holes. 

However, an internship at Gelens lab for Dynamics in Biological Systems in 2024 sparked his fascination for complex systems and biology. This inspired him to start a PhD in the lab in October 2025, where he aims to develop theories and models, that combine dynamical systems theory and Markov jump processes, to explain how temperature influences biological systems.

In his recent research he has focused on temperature effects in early embryonic development and nonlinear chemical oscillations, including the Belousov-Zhabotinsky reaction. He is also collaborating with Julian Voits and Prof. Ulrich Schwarz at Heidelberg University, who he is visiting in the coming two weeks. 

His work has been recognized with the Best Poster Prize at the 2026 EMBL Biological Oscillators conference and the 2026 Belgian Vocatio award.