A team of researchers, including members of the MIT Node of the NASA Astrobiology Institute (NAI), have revealed new insight into why organisms on the ancient Earth began to grow larger. Life began on our planet as single-cell microorganisms, but today the Earth supports a diverse array of multicellular life. The new study could help explain the advantages that early organisms gained from an increase in size.

The study, published in Current Biology, shows how primitive organisms called Ediacara became larger to help access nutrients in ocean currents. Ediacara were leaf-shaped, grew up to a meter off of the seafloor, and are considered one of the earliest examples of large, multicellular life.

The team used 3-D models to reconstruct the ocean currents from 580 million years ago. They found that nutrients were concentrated in certain areas, resulting in dense communities of bacteria and multicellular organisms that had to fight for resources. The researchers believe that increasing size could have been the advantage that Ediacara needed to out-compete the smaller, more efficient microbial biofilms.