A 20 year experiment appears to have observed the chance development of an evolutionary innovation. 12 populations of E. Coli, derived from a single bacterium, have been cultured separately and observed. Sometime around the 31,500th generation of just one population the bacteria became able to metabolise the citrate in their culture medium. E. coli cannot normally do this.
The lead scientist, Richard Lenski, has regularly taken some of the bacteria from each population and stored them so that he can try to study the bacteria at any point during the study. He can go back in time and analyse (and regrow from frozen) the bacteria before, during and after any mutation. This ability to metabolise citrate seems to have occurred through one or more mutations, and would provide evidence against creationist arguments that this is impossible.
This fascinating work adds yet more evidence to the theory of evolution, and has built upon existing evidence that chance mutations occur (but are more easily recognised when they give negative effects). The work may take a very long time to reproduce given the tiny probability for multiple genetic mutations to occur and give a positive effect upon an organism, but the bacteria stored by Dr Lenski will demonstrate the timeline and how exactly the citrate mutation came about.
Read more at New Scientist.
And much more from Carl Zimmer’s blog.
Blount et al., 2008. Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli. PNAS 105, 23; 7899-7906.
This work is very important. This tiny bacterium is telling us about our place in the universe.
