A groundbreaking study conducted at the Georgia Institute of Technology has revealed the astonishing evolution of a common brewer's yeast, Saccharomyces cerevisiae, which has grown from a single cell into a multicellular organism approximately the size of a flea. Through careful selection and cultivation of the yeast's largest and fastest-growing clusters over thousands of generations, researchers witnessed an unprecedented increase in size, with the organism now containing over half a million clonal cells—20,000 times larger than its ancestor. This ongoing study, known as the Multicellularity Long-Term Evolution Experiment (MuLTEE), sheds light on the complex process of how single-celled organisms transform into multicellular life forms.
The findings demonstrate a new physical mechanism that facilitated the yeast's remarkable growth. The cells developed larger branches, reducing overall density, and intertwined with one another to form a cluster resembling modern gels. This new structure made the organism significantly stronger, exhibiting toughness similar to wood. The study also revealed the role of oxygen in setting limits on evolutionary progress, as yeast populations relying on oxygen faced limitations in size compared to those that didn't. The research emphasizes the crucial role of oxygen levels in the evolution of multicellular organisms.
The study's groundbreaking insights into the evolution of multicellular life forms hold promise for a deeper understanding of early life on Earth. With further observations planned for the years to come, researchers are excited about the potential to unravel the mysteries of early multicellular evolution and explore the interplay of evolutionary cell biology and biophysical traits.