MIT researchers uncover ancient sea sponge ancestors from over 541 million years ago

In the recent study conducted by geochemists at the Massachusetts Institute of Technology, researchers explored ancient rocks dating back over 541 million years, specifically from the Ediacaran Period. Their investigation focused on identifying the prevalence and characteristics of chemical fossils within these rocks. These chemical fossils are molecular remnants that have been preserved over eons and represent the first potential animals that inhabited Earth. Notably, the analysis revealed a connection between these fossils and the ancestors of modern-day demosponges, a type of sea sponge. This significant discovery adds a new dimension to our understanding of early life forms on Earth. The researchers utilized a combination of fossil analysis and studies of contemporary demosponges in their research. The chemical fossils detected were specific forms known as steranes, which derive from sterols found in the cell membranes of complex organisms. In their work, they highlighted the identification of two types of steranes: 30-carbon and 31-carbon, derived from ancient life. This is a groundbreaking development because prior research had only confirmed the presence of the 30-carbon steranes in earlier studies. The presence of the 31-carbon sterane was unexpected and raises intriguing questions about the evolutionary history leading to modern sea sponges. One of the motivations behind this study was to authenticate biomarkers, ensuring they originated from biological sources rather than contamination or geochemical processes. By examining the chemical makeup of living demosponges, the research team amassed strong evidence that links these ancient steranes to their modern counterparts. These findings indicate that the ancestors of today’s sea sponges not only lived in ancient oceans but possibly had soft-bodied structures and lacked silica skeletons, in line with the characteristics of modern demosponges. With this study, the MIT researchers shed light on the origins of complex life forms, suggesting that soft-bodied animals like sea sponges played a crucial role in the early stages of life on Earth. Their work builds upon previous findings while also emphasizing the importance of interdisciplinary approaches combining geology and biology. This breakthrough reshapes our understanding of evolutionary biology and the timeline of life on our planet, providing compelling evidence of some of the earliest animals that existed on Earth, which predominantly inhabited marine environments.