More than 500 million years ago, single-celled organisms on the Earth's surface began forming multicellular clusters that ultimately became plants and animals. Just how that happened is a question that has eluded evolutionary biologists.
But scientists in the University of Minnesota's College of Biological Sciences have replicated that key step in the laboratory using natural selection and common brewer's yeast, which are single-celled organisms. The yeast "evolved" into multicellular clusters that work together cooperatively, reproduce and adapt to their environment in essence, precursors to life on Earth as it is today.
Their achievement is published in the January 16 issue of Proceedings of the National Academy of Sciences.
It all started about two years ago with a casual comment over coffee that bridging the famous multi-cellularity gap would be "just about the coolest thing we could do," recall postdoctoral researcher Will Ratcliff and associate professor Michael Travisano, both from the Department of Ecology, Evolution and Behavior.
So they decided to give it a try. Then came the big surprise. It wasn't actually that difficult. Using yeast cells, culture media and a centrifuge, it only took them one experiment conducted over about 60 days, says Travisano, who is senior author on the PNAS paper.
"I don't think anyone had ever tried it before," says lead author Ratcliff. "There aren't many scientists doing experimental evolution, and they're trying to answer questions about evolution, not recreate it."
Despite their modesty, the achievement has earned praise and admiration from evolutionary biologists around the world.
"To understand why the world is full of plants and animals, including humans, we need to know how one-celled organisms made the switch to living as a group, as multicelled organisms," said Sam Scheiner, program director in the National Science Foundation (NSF)'s Division
|Contact: Jeff Falk|
University of Minnesota