A Single Mutation May Have Sparked Multicellular Life

Millions of years ago, a very important change – or mistake – in our ancestors’ DNA occurred, and it may explain why we’re all here.

Single-celled organisms swimming through a primordial sea was what life consisted of long ago. But at some point, cells started coming together to create entities with two, ten and eventually millions, of cells. This led to the rise of organisms containing different kinds of cells, which paved the way for the creation of tissues and organs, and eventually life as we know it.

Now, researchers from the University of Oregon say they’ve traced the steps of evolution backward through the phylogenetic tree and pinpointed a single mutation that they believe ushered in the transition from unicellular to multicellular organisms.

The researchers focused on an important part of cell division, or mitosis, during which two daughter cells created through cell division are placed in the proper orientation within the tissue. Protein structures, called mitotic spindles, are instrumental to this process, because they line up daughter cells with marker proteins on the cell wall.

When the spindle isn’t oriented properly, malformed tissue and cancer can result. In many animals, an ancient protein controls the orientation of the spindle to ensure it ends up in the correct position. If researchers discover when these ancient protein structures evolved the ability to position spindles, the thinking goes, they could pinpoint the origin of multicellular life.