The Physics of Cold Water May Have Jump-Started Complex Life

Frigid conditions during the "Snowball Earth" periods, when the planet was largely covered in ice, may have facilitated the evolution of complex multicellular life. Research led by Carl Simpson at the University of Colorado, Boulder, suggests that as seawater cools, it becomes more viscous, making it difficult for single-celled organisms to navigate and feed. This increased viscosity could have pressured these organisms to adapt by forming larger groups, potentially leading to multicellularity.

Simpson's team conducted experiments with green algae, observing that as they were placed in progressively thicker gel, they began to form larger, coordinated clusters. These clusters were able to swim collectively, maintaining their speed and efficiency in nutrient acquisition. Remarkably, even after returning to normal viscosity, these algae remained grouped together for many generations, indicating a possible evolutionary shift.

The findings challenge traditional views on the emergence of multicellular life, emphasizing the role of physical environmental factors rather than solely geochemical triggers. While the research is still in preprint form and awaits peer review, it provides a novel perspective on how ancient environmental conditions may have influenced biological innovation. The study highlights the importance of understanding the interactions between organisms and their physical environments in the context of evolutionary biology.