In his fourth-floor lab at Harvard University, Michael Desai has created hundreds of identical worlds in order to watch evolution at work. Each of his meticulously controlled environments is home to a separate strain of baker’s yeast. Every 12 hours, Desai’s robot assistants pluck out the fastest-growing yeast in each world — selecting the fittest to live on — and discard the rest. Desai then monitors the strains as they evolve over the course of 500 generations. His experiment, which other scientists say is unprecedented in scale, seeks to gain insight into a question ( http://www.simonsfoundation.org/quanta/20140717-the-new-science-of-evolutionary-forecasting/ ) that has long bedeviled biologists: If we could start the world over again, would life evolve the same way ?
Many biologists argue that it would not, that chance mutations early in the evolutionary journey of a species will profoundly influence its fate. “If you replay the tape of life, you might have one initial mutation that takes you in a totally different direction,” Desai said, paraphrasing an idea first put forth by the biologist Stephen Jay Gould in the 1980s.
Desai’s yeast cells call this belief into question. According to results published in Science in June ( http://www.ncbi.nlm.nih.gov/pubmed/24970088 ), all of Desai’s yeast varieties arrived at roughly the same evolutionary endpoint (as measured by their ability to grow under specific lab conditions) regardless of which precise genetic path each strain took. It’s as if 100 New York City taxis agreed to take separate highways in a race to the Pacific Ocean, and 50 hours later they all converged at the Santa Monica pier.
http://www.wired.com/2014/10/evolution-paths-fitness/
(Score: 2) by SlimmPickens on Saturday October 04 2014, @07:50PM
The single biggest agent for change was the introduction of high levels of oxygen to the atmosphere. The proteins and enzymes that stick cells together pre-existed multicellular by perhaps billions of years (as tools for eating other bacteria etc) but those reactions are very energy intensive and simply weren't feasible on a large scale until there was plenty of oxygen in the atmosphere. There's not really a lot of bacteria nowadays that do not depend on oxygen.
Learned this from Neil Shubin's excellent book, Your Inner Fish.