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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.
Experimental evolution of multicellularity
And PNAS has it listed as open access, which means you should be able to download the full text regardless of your subscriber (or non-subscriber) status. Just click the Full Text link.
Damn_registrars has no butt-hole. Damn_registrars has no use for a butt-hole.
Do the mechanisms which originally created life still occur? Or is "The Genesis Event" so rare that it was a one-time occurrence billions of years ago?
God still holds the copyright for the original genesis event. It should have entered the public domain, but the copyright just keeps getting extended, and extended for billions of years. God keeps raking in the royalties and has no incentive to create new works, which is why you haven't heard anything from him lately.
Actually, the opposite of what you say is true. That's the whole point of using the word "selection" in the phrase "natural selection". Anything that helps the organism survive and reproduce better in its environment is a selective pressure. So if you postulate that there exists somewhere on the planet where multi-cellularism is a selective force, then this experiment replicates those conditions.
E pluribus unum
Reading the comments on the physorg page made by intelligent design supporters, I have come to a conclusion. Some of us have not evolved far beyond yeast.
Yeast already has a natural ability to flocculate, differing by strain. All they did is use artificial selection to produce a new strain of yeast with higher flocculation. The article mentions that yeast evolved from a multicellular life form and that the next experiment will use single celled organisms which did not evolve this way. I suspect it will take much longer than 60 days to see any results.
Well, it's not that hard to create a similar environment in the real world, they take too long to get grant money for. Consider, for example, a microbe growing in a hot spring that needs a very high temperature to function properly (like every molecular biologist's friend, Thermus aquaticus.) If that thing floats to the top of the pond, it might get cold and die. Evolutionary pressures such as sink-or-die aren't that implausible.
Think of it this way: a random walk will get to every possible location eventually. If you push it in a certain direction, it'll simply get there sooner. But if it doesn't get there when you do, then there's no chance it'll ever get there on its own. Unless they tampered with the genes of the yeast in question, these results are completely legitimate.
Bio questions? Ask me to start a Q&A journal. Computer analogies available for most topics!
Once again, great successes hailed while ignoring the elephant in the room: the researchers cheated by selecting out certain ones (those that sank to the bottom.) in TRUE life-by-incremental-changes, every event is random, including which cells are selected out of the tube to prosper.
False.
The purpose of this "selection" was simply to simulate a larger environment. If this occurred in a big place relative to the size of the yeast, let's call this imaginary place the ocean, it is highly likely the yeast wouldn't be contained to a test tube. It would disperse on its own. Selecting certain ones and continuing to examine them is the same as zooming in and following the large ones in the ocean you'd like to examine. The centrifuge is not meant for culling, selective breeding or to "intelligently design evolution in yeast".
N.B. I have no idea about the atmospheric requirements for this experiment as I skipped that part of the original article. For all I know the bigger place could have been a rock, a lake, a cloud or an iceberg. The argument is based upon the false implication that yeast only exists in constrained environments.
Not to diminish the importance of multi-cellularity (and of this discovery) but wasn't the development of Eukaryotes (cells with Nuclei and other differentiated organelles) the big step needed for complex life? I mean with chloroplasts you get plants and mitochondria (or mitoklorines for you Star Wars fans) you get animals.
With multi-cellularity and prokaryotes you get strombolites (algal mats).
That said, it shows that evolution can happen quite quickly and can overcome some serious obstacles in a short amount of time in a very limited scope (a laboratory workbench). When multiplied by geologic ages and oceans of room is it any wonder that life has evolved in so many fascinating ways?
I suspect it's not "evolution" at all, but subtly bad science (i.e. a scientist gunning for more grant money). DNA can express in many ways given varying environmental conditions, without the mutations that characterize true evolution -- and artificially forcing genetic drift by selecting for the bottom-clumpers is certainly VERY DIFFERENT from having gravity serve as the "selection pressure."
It's well known DNA can express in many different ways without true evolution. We've come a long way from the theory of Lamarckian evolutionary theory (evolution of acquired characteristics). One is example: exons, which can express differently across generations based on environmental conditions-- without actual change to the DNA.
I'm thinking this great discovery will get pounded upon by other biologists pretty quickly -- and put in its proper place as an interesting science experiment that really does not advance the field much if at all. INTERESTING evolution would be a group of mutations that lead to a multicellular outcome. That's NOT what these guys 1) demonstrated happened (multicellular DNA base-pair-causing mutations) or 2) proved was the actual genetic cause at the molecular-biology level.
Except he didn't plan the form, look or workings of the organism, which means he didn't actually design.
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I think if anyone left Digg to come to Slashdot, the next stage would be suicide, not going back to Digg.
It pays to be obvious, especially if you have a reputation for being subtle.
I brew (and judge) beer... different strains of brewers yeast already have widely varying behaviors with regards to how they settle out. Yeast with "low flocculation" tend to remain in suspension for weeks, consuming more of the sugars (drier, more alcoholic beer); yeast with "high flocculation" tend to clump together and settle after a few days, leaving more residual sugar (sweeter/heavier beer). This is widely known already in the brewing community. These strains have evolved over the years to suit the preferences and procedures of individual breweries. So all these guys have really done is to repeat in a controlled environment the same selective breeding that brewers have been doing (whether they understood it or not) for centuries.
Take a look here; if you click through to each individual strain of yeast, you'll see that there's a spec for flocculation (tendency to clump) and attenuation (tendency to consume sugars); there's a pretty good (though not perfect) inverse correlation between the two.
The only thing really novel here is the claim that these yeast clumps somehow represent a first step towards multi-cellular life. Interesting, but -- while I'm not dismissing it out-of-hand -- I'm definitely taking it with a pinch of salt.
From life. I'm not surprised.
Life evolves. Dead things don't. And dead things don't evolve into life.
Wake me up if that changes.