In the latest issue of the journal Science, Will Ratcliff, assistant professor in Georgia Tech Biology, has a piece on a new theory he and Eric Libby, from the Santa Fe Institute, are positing that explains the rules governing how life may have evolved from single-celled organisms into multi-cellular productions.
Ratcliff:
How multicellular complexity arises in evolution is a central problem in biology, but we know little about how early groups evolved into the complex multicellular organisms we see today. The first steps in this process are often a big hurdle, because the fitness interests of cells and groups of cells can conflict. In this short piece, we propose a new idea for how early life in multicellular groups can be stabilized. Ratcheting is the idea that once cells in groups evolve traits that costly to single cells, the path back to unicellularity is cut off.
Apoptosis is a great example of this. At the single cell level, it causes the death of the organism, but in a multi-cellular organism it can be a good thing because it allows for things like the death of damaged cells, disease prevention as well as helping organisms regulate the number and size of offspring they produce.
You can imagine that there are many other examples that allow groups to get more complex and at the same time makes it harder for them to get off the multicellular train. We’re testing a few of these experimentally right now.
Full Paper: http://www.sciencemag.org/content/346/6208/426.full