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Multicellular Life Evolves In Months, In a Lab
ananyo writes "The origin of multicellular life, one of the most important developments in Earth's history, could have occurred with surprising speed, U.S. researchers have shown. In the lab, a single-celled yeast (Saccharomyces cerevisiae) took less than 60 days to evolve into many-celled clusters that behaved as individuals. The clusters even developed a primitive division of labor, with some cells dying so that others could grow and reproduce. Multicellular life has evolved independently at least 25 times, but these transitions are so ancient that they have been hard to study. The researchers wanted to see if they could evolve multicellularity in a single-celled organism, using gravity as the selective pressure. In a tube of liquid, clusters of yeast cells settle at the bottom more quickly than single cells. By culturing only the cells that sank, they selected for those that stick together. After many rounds of selection over 60 days, the yeast had evolved into 'snowflakes' comprising dozens of cells."
This is likely just re-emergence of previously evolved and currently dormant behavior.
That's a big question! We currently believe that the circumstances that created life were pretty harsh in some respects and extremely mild in others. There are a number of different ideas floating around, including the proverbial primordial soup, clouds of space dust (panspermia), and a boiling puddle of fat. Most likely, the conditions that were on Earth billions of years ago (a hot boiling hell with a mostly hydrogen atmosphere, amongst other things) contributed substantially to the factors that led to life's rise.
Bio questions? Ask me to start a Q&A journal. Computer analogies available for most topics!
This has indeed been pondered! We're pretty sure that all life that presently exists all comes from one root, however. If there ever were alternative life-starting events, they didn't survive. The reason for this is that all extant organisms share a number of completely arbitrary decisions called chirality (if you know any physics, that's left-handed vs. right-handed molecular symmetry.) Chirality is completely random in the chemical reactions that produce amino acids and nucleotides, but absolutely fixed, in the same way, in every living organism we've studied. A number of environmental tests have been conducted specifically to look for organisms of contrary chirality, but we haven't found anything yet.
Bio questions? Ask me to start a Q&A journal. Computer analogies available for most topics!
Bzzt. Please review the difference between mass and density and the relationship between density and buoyancy.
First entomology, then virology, and finally bioinformatics systems. Bugs follow me wherever I go.
The summary is true, but ultimately misleading.
This is evolution, and it did happen in months. What it doesn't account for is getting the clumping gene in the first place, and that the likelihood of getting selection pressures as extreme as the ones in the lab is fairly low.
They've proven that yeast has the capacity to evolve in this way given the right selection pressures, which is interesting. With additional research they may be able to prove that many other single celled life forms have the same capacity, from which we may extrapolate that the gene responsible for this behavior either occurred very early or is a relatively minor mutation.
The "more quickly than we believed" part is probably bogus. They applied extreme selection pressures to this particular colony of yeast and so they got an extreme time scale result the same would happen in any species if you extrapolated for the length of a given generation. You could do the same thing to humans for some arbitrary characteristic.