Evolution: Outside-in?



Theories that explain how the ‘primordial soup’ from which the first cell formed are challenged by a new model presented by Gareth Griffiths.


The theory that all life evolved from one source — the last common ancestor — as proposed by Charles Darwin and others, enjoys considerable support among evolutionary biologists. But questions remain about how the features that comprise a cell — membrane, cytoskeleton, genetic material — evolve to form a functional cell.



Numerous models propose that the formation of cells occurred inside randomly formed compartments (called vesicles) by a process known as the ‘cytoplasm within the vesicle’ scenario. But experimental validation of this theory is limited. Gareth Griffiths now describes an alternative theory that challenges previous dogma: the ‘cytoplasm outside the vesicle’ scenario. This theory states that early cytoplasmic components evolved in fresh water, probably on a mineral rock surface that also anchored small vesicles upon which the cytoplasm evolved.



The crucial difference is that this model proposes that the cytoskeleton, which maintains the three-dimensional structure of a cell and is involved in diverse cellular functions such as motility and transport, is required before, and as part of, the mechanism that led to cell formation. This theory provides an explanation to some of the mystifying questions in evolution, such as how two of the main kingdoms of life — prokaryotes (such as bacteria) and eukaryotes (such as mammals and plants) — might have diverged.



Contact

Gareth Griffiths (European Molecular Biology Laboratory, Heidelberg, Germany)
Tel: + 49 6221 387 8267 Email: gareth-griffiths@embl-heidelberg.de