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Guybrush 01-18-2012 04:11 AM

Multicellular Life Evolves in Laboratory
 
I've yet to read the scientific article, but the news article is interesting. :)

Multicellular Life Evolves in Laboratory | Wired Science | Wired.com

An evolutionary biologist has made yeast which are normally unicellular free-floaters cooperate in permanent multicellular arrangements simply by regularly removing free floating single individuals from his breeding tanks. In other words, he simply introduced artificial selective pressure against the typical single celled arrangement (meaning the environment favours clumping) and let natural evolution do the rest.

It's such a simple experiment which basically anyone could do and the results are still quite interesting. For biologists, it confirms something we know while still shedding some new light on the hows (f.ex it didn't take very long to see results), but for many of the evolution doubters out there, this should be even more significant as it demonstrates how multicellularity can start.

duga 01-18-2012 11:16 AM

This is so cool! With the speed and relative ease that this took, imagine what it means in terms of evolution on other planets or even the drastic turns our evolution could have taken. If the environment had been even slightly different than the one our ancestors evolved in, we would be very different creatures.

Sadly, we biologists can add more and more evidence supporting evolution but we are going to keep getting the same responses... "If you are so sure, why is it just a theory?" Bah... A lot of times I just want to give up. The one thing we can't seem to make them understand is that if we are shown significant evidence disproving evolution, we would all start questioning it. Hell, I'd be one of the first ones to say we were wrong. Oh well.

Sorry for the rant. As far as the article goes... I will definitely have to track down that publication. Applying artificial selection has been something I've been very interested in. In fact, I've had ideas as a plant biologist that involve taking plants that produce novel drugs and studying how they evolved to produce them (some produce them to deter predators while some are meant to attract pollinators) and perhaps apply artificial pressure and get them to artificially evolve the drug to do something that we want. In a way, marijuana growers already do this to get a desired effect from their strain.

We are obviously a long way off from being able to do this with a great deal of control, but it's something to think about. I'm glad to see it in action.

Janszoon 01-18-2012 11:18 AM

Like Duga said, I doubt this (or anything) will convince the anti-evolution crowd unfortunately. Still pretty neat though!

Neapolitan 01-18-2012 12:41 PM

To me it's like looking at a glass and saying it is half empty or half full. Evolution didn't take place for the free-floating single cell of the brewer's yeast, in the experiment they were discarded, so to me that leaves questions about the experiment. What if in that yeast culture there were two types of yeast (for the sake of clarity & brevity name them A and B) yeast A is not prone to multi-cellularity and yeast B is prone to multi-cellularity, they both co-exist in the culture before the experiment took place. And the experiment just separated the two traits and it favoured the yeast that would give rise to the desire result of multi-cellularity instead of the undesired uni-cellularity.

It reminded me of Russian experiment done on wild fox, fox were made domesticated in time they lost many traits of fox like bushy tail but when released fox back into the wild they gain back those traits like bushy tail. So like the fox tail what would happen to that multi-cellular yeast if it was released back into its natural environment would it regress to natural state of uni-cellularity, and is multi-cellularity a trait it can revert to back and forth?

Quote:

Originally Posted by duga (Post 1143860)
The one thing we can't seem to make them understand is that if we are shown significant evidence disproving evolution, we would all start questioning it.

I think that should be always done. Experiments and the hypothesis dealing with evolution should be questioned anyway that's just a part of science.

Guybrush 01-18-2012 01:03 PM

Neapolitan, I assume what you're really wondering is whether the clumping trait is something the genomes of unicellular yeast are capable of; that they can arrange themselves either on their own or in clumps similar to how a rabbit can change from a dark summer coat to a white winter coat without having to "evolve" their DNA. The ability for a genome to express itself in different ways is called plasticity and it's something biologists study and are aware of. I've not read the scientific article yet, but I'm sure the scientific article will document some of the directional genetic changes which are a response (evolution) to the artificial selective pressure.

Plasticity and evolution is pretty basic stuff and it would be a very strange place to make a mistake. These guys would know about it and would know that in order to call it evolution, they should prove that what happened is not just another expression within the range of the organisms plasticity, but a novel behaviour caused by a genetic evolutionary response to the artificial selection pressure.

If you were to release multicellular yeast into an environment where being unicellular has the highest fitness benefit, then they should evolve back to a unicellular arrangement. I'm not sure if you feel that would disprove evolution and, if so, why.

edit :

Quote:

Originally Posted by duga (Post 1143860)
This is so cool! With the speed and relative ease that this took, imagine what it means in terms of evolution on other planets or even the drastic turns our evolution could have taken. If the environment had been even slightly different than the one our ancestors evolved in, we would be very different creatures.

Sadly, we biologists can add more and more evidence supporting evolution but we are going to keep getting the same responses... "If you are so sure, why is it just a theory?" Bah... A lot of times I just want to give up. The one thing we can't seem to make them understand is that if we are shown significant evidence disproving evolution, we would all start questioning it. Hell, I'd be one of the first ones to say we were wrong. Oh well.

Sorry for the rant. As far as the article goes... I will definitely have to track down that publication. Applying artificial selection has been something I've been very interested in. In fact, I've had ideas as a plant biologist that involve taking plants that produce novel drugs and studying how they evolved to produce them (some produce them to deter predators while some are meant to attract pollinators) and perhaps apply artificial pressure and get them to artificially evolve the drug to do something that we want. In a way, marijuana growers already do this to get a desired effect from their strain.

We are obviously a long way off from being able to do this with a great deal of control, but it's something to think about. I'm glad to see it in action.

It's definetly an interesting field and probably quite satisfying to work with. I can imagine biologists becoming quite fond of and excited about their breeding tanks/whatevers where they're evolving specific traits :D

Neapolitan 01-18-2012 01:31 PM

Well, Evolution outside of science can be a highly debatable topic, I prefer not to favour either side of it.

What is more intriguing to me is the road not taken. What about those singular yeast cell do they also mutate but without becoming multi-cellular or are they also prone to (like you say) placidity? I think if there was a way to map the genomes every day for 60 days (time given in the article for the experiment) for both yeast A and yeast B and any other yeast that branches off to see molecular change in the DNA for each one - I might be more satisfied, for me that would be proof of something happening.

This is something I wondered about after reading the article: how many generations would it take for a single cell yeast to become multicellular yeast and if release into an environment non-conducive for multi-cellularity would they die off or survive and if they survive how many generations would it take them to revert back to singular cell form, and how much of a difference in their DNA would there be from the original yeast that was used when they began the experiment?

Janszoon 01-18-2012 01:35 PM

Quote:

Originally Posted by Neapolitan (Post 1143885)
Well, Evolution outside of science can be a highly debatable topic, I prefer not to favour either side of it.

What do you mean by "evolution outside of science"?

Guybrush 01-18-2012 02:30 PM

Quote:

Originally Posted by Neapolitan (Post 1143885)
What about those singular yeast cell do they also mutate but without becoming multi-cellular or are they also prone to (like you say) placidity? I think if there was a way to map the genomes every day for 60 days (time given in the article for the experiment) for both yeast A and yeast B and any other yeast that branches off to see molecular change in the DNA for each one - I might be more satisfied, for me that would be proof of something happening.

Organisms' DNA mutates. Of course the genetic makeup of the yeast would change over time, no matter what you did with it. We know this from a wealth of studies already. Science is way past that point and it's about time the general populace catches up.

The interesting thing here is not actually that stuff evolves. Micro organisms (and life in general) evolve in the labs and elsewhere and that's nothing new. The interesting thing here is the evolution of the multicellular trait. Many have thought it a very difficult trait to achieve, but this scientist and his study shows how quickly it can happen in yeast and that can tell us something about how the trait first appeared in other lineages.

I find it a bit difficult to respond to you because I'm not sure we're on the same page. For example, I don't know to what extent you understand evolution. Perhaps you believe genetic mutations are very rare?

duga 01-18-2012 07:38 PM

Yeah, I'm getting the impression he doesn't quite understand.

Neapolitan, what is your understanding of what is going on? If they were to move the multi-cellular yeast to a different environment, surely it would die. It only has an advantage in the environment they "evolved" it in.

Electrophonic Tonic 01-18-2012 07:51 PM

This reminds me a lot of the Miller-Urey experiment. Basically, it proved that the elements and conditions on the early Earth some 4-3 billion years ago could create live. The experiment ran for a few weeks, and they found amino acids.

http://upload.wikimedia.org/wikipedi...ent-en.svg.png

Yet again, science has the tangible evidence for evolution but no one on either side of the argument will change their position no matter what.

And, if anyone can appreciate multicellular life, it's my Cambrian friend below my user name. The Anomalocaris approves.

Neapolitan 01-20-2012 11:02 PM

Quote:

Originally Posted by Janszoon (Post 1143887)
What do you mean by "evolution outside of science"?

I guess what I mean is when two scientist are in a lab doing a study of something scientific, or doing an experiment for the sake of science, the mention of "evolution" in a conversation is quite mundane and non-eventful, but say two non-sceintist are conversing about science the mere mention of "evolution" outside of scientific world that dialogue can spiral out of control into an heated argument. That's what I want to avoid.

Quote:

Originally Posted by tore (Post 1143902)
Organisms' DNA mutates. Of course the genetic makeup of the yeast would change over time, no matter what you did with it. We know this from a wealth of studies already. Science is way past that point and it's about time the general populace catches up.

And right now I feel like you're implying the general populace is me.

Quote:

Originally Posted by tore (Post 1143902)
The interesting thing here is not actually that stuff evolves. Micro organisms (and life in general) evolve in the labs and elsewhere and that's nothing new. The interesting thing here is the evolution of the multicellular trait. Many have thought it a very difficult trait to achieve, but this scientist and his study shows how quickly it can happen in yeast and that can tell us something about how the trait first appeared in other lineages.

I think the evolving part is just as interesting as in the result of multi-cellularity.

Quote:

Originally Posted by tore (Post 1143902)
I find it a bit difficult to respond to you because I'm not sure we're on the same page. For example, I don't know to what extent you understand evolution. Perhaps you believe genetic mutations are very rare?

Well I wasn't excited too much about the experiment because they seem to rig it for the desire result, not because I do or don't believe in the frequency that mutations occur.

I guess the page I was coming from was like: Was multi-cellularity already a forgotten part of this organanism pre-historic past? Was there some environmental change that forced this multi-cell yeast of the past to evolved in singlular cellularity of today. But still even after the evolutionary step it kept those multi-cellular codes in it's DNA but they remained dormant, it never reach multi-cellularity form because whatever environment that organonsim once live no longer exist, and in the new environment singular-cellularity was more advantageous for survival. Then along came a scientist and he did an experiment by shaking vials, in reality he didn't forced evolution on the yeast but unwittingly unlocked a pre-existing code that was already there - the multi-cellularity code. I think that is more my point than the validity of evolution or how much I know about evolution.

Quote:

Originally Posted by duga (Post 1143996)
Yeah, I'm getting the impression he doesn't quite understand. Neapolitan, what is your understanding of what is going on?

That's the whole problem I don't really trust the procedure - not that that I lack the understanding of what is going on with the experiment.

Quote:

Originally Posted by duga (Post 1143996)
If they were to move the multi-cellular yeast to a different environment, surely it would die. It only has an advantage in the environment they "evolved" it in.

Well it depends - they might die out. I wouldn't rule that out entirely, statistically speaking there could be some environment somewhere on this vast planet where multi-cellular brewer's yeast could survive in - in a hypothetical scenario - there could an environment that could be similar to that of the experiment.

Guybrush 01-21-2012 05:10 AM

Quote:

Originally Posted by Neapolitan (Post 1144700)
I think the evolving part is just as interesting as in the result of multi-cellularity.

The reason the evolving part is not as interesting is that it's been proven many times before and would show nothing new. Many times, micro organisms have adapted to artificially induced selection pressures

Quote:

Originally Posted by Neapolitan (Post 1144700)
I guess the page I was coming from was like: Was multi-cellularity already a forgotten part of this organanism pre-historic past? Was there some environmental change that forced this multi-cell yeast of the past to evolved in singlular cellularity of today. But still even after the evolutionary step it kept those multi-cellular codes in it's DNA but they remained dormant, it never reach multi-cellularity form because whatever environment that organonsim once live no longer exist, and in the new environment singular-cellularity was more advantageous for survival. Then along came a scientist and he did an experiment by shaking vials, in reality he didn't forced evolution on the yeast but unwittingly unlocked a pre-existing code that was already there - the multi-cellularity code. I think that is more my point than the validity of evolution or how much I know about evolution.

This is pretty much the plasticity scenario I mentioned in my earlier post. I'm sure they're trying to keep up with the genetic changes of the organisms and will document proof.

I should perhaps mention that an example of evolution does not necessarily require new mutations. We call it evolution even when the allelic frequencies differ from one generation to the next. That means that if there is two versions of a clumping gene, one which creates a unicellular yeast and another which makes a multicellular type yeast and in the generation you're looking at there is 9 unicellular genes for every 1 multicellular gene .. if the multicellular type yeast have more reproductive success, in the next generation you could have 7 unicellular gene versions for every 3 multicellular genes.

We call versions of genes alleles. In this case, even though both alleles were present at the start, the ratio between two alleles has changed from one generation to the next. As a result, the genetic makeup of the yeast population has changed somewhat. That's also called evolution.

edit :

The good old Hardy Weinberg principles demonstrate what conditions you'd have to meet in order not to evolve.
  • Population size has to be huge (infinite size basically)
  • Mating has to be random (no sexual selection)
  • There can also be no non-sexual selection pressures
  • There can be no mutations
  • There can be no gene flow (gene migration from other populations)

These criterias are used as a reference to see how fast a population of animals evolve by looking at specific alleles and monitoring how they change in frequencies from one generation to the next.

If you understand the concept of evolution and these principles, you'll see that life can't not evolve.

edit 2 :

For the record, I don't believe that what we're seeing in the study is merely a change in the frequency of old alleles. I'm just saying that you could call it evolution even if that was the case. As it's a novel trait which the yeast seem to have adapted over time (gradually changing the way they work/look/behave), I'm still sure they will document changing DNA and not just changing allele frequencies.

Janszoon 01-21-2012 06:12 AM

Quote:

Originally Posted by Neapolitan (Post 1144700)
I guess what I mean is when two scientist are in a lab doing a study of something scientific, or doing an experiment for the sake of science, the mention of "evolution" in a conversation is quite mundane and non-eventful, but say two non-sceintist are conversing about science the mere mention of "evolution" outside of scientific world that dialogue can spiral out of control into an heated argument. That's what I want to avoid.

So you want to avoid talking about reality because there are some crazy people who get offended by it?

MoonlitSunshine 01-21-2012 07:56 AM

Quote:

Originally Posted by Neapolitan (Post 1144700)
Well I wasn't excited too much about the experiment because they seem to rig it for the desire result, not because I do or don't believe in the frequency that mutations occur.


That's the whole problem I don't really trust the procedure - not that that I lack the understanding of what is going on with the experiment.


That's.... kinda the point. You understand the concept of Natural Selection? The scientists wanted to show that a usually uni-cellular organism could be forced to evolve into a predominantly multi-cellular organism, provided that it was "optimal" to do so. In order to show this, they "rigged" the experiment so that the multi-cellular version should thrive and dominate. This is exactly what happened.

The "removing" of the uni-cellular free floating yeast at intervals was used to emulate "dying out" in nature - think of it like a plant evolving in two strains, one which kills what eats it and the other which doesn't - the predators would learn over time to eat only the non-lethal one and thus the non-lethal one would eventually die out (or at least shrink vastly in population) over time, provided it didn't have other more profitable mutations like a faster propagation rate.

"Evolution" isn't just the random mutation of organisms. Mutation happens as a matter of course, everything mutates, Evolution is the combination of Mutation and Natural Selection, where the Mutations which survive more successfully naturally grow to form the dominant part of the base population.

To relate that to this experiment, the environment was set up so that multi-cellular life had a greater survival chance. Their method of doing so might have been rather crude, but it was as effective and essentially equivalent to the free-floaters "dying out" due to other more natural reasons.

Or at least, that's how I've come to understand it.

duga 01-21-2012 09:44 AM

This thread is the perfect example of a lack of understanding and thus non acceptance of firm data. Neapolitan, I applaud you getting in on the discussion but seriously... You don't understand what is going on fully. Either that or you are trying so hard to play devils advocate that it is coming off that way.

Trust me when I say a scientist's biggest critics are other scientists. Paper go through scrutinous reviews from peers and experts in the field so when the paper comes out, you can be fairly confident it represents a reliable piece of evidence towards the concept they are studying. Granted, this isn't always the case which is why we are still critical.

This study in particular seems like a solid bit of research. It doesn't prove evolution on a grander scale, but it is just one more piece of evidence (on top of mounds I other bits) that prove the concept.

Neapolitan 01-22-2012 10:16 AM

^ Duga,

Instead of whole heartily agreeing with this experiment I think to myself isn't there something in this experiment that should had done differently. How about you are you totally fine with the proceedure? If there was something you would had done differently what would it be? Many experiments I hear of uses a placebo, maybe in this case a placebo should had been used. Say for instance have three unmarked vials give two scientist the brewer's yeast and the third scientist amoebae as a placebo and see if the same result of multi-cellularity would happen for all three or just the first two.

Quote:

Originally Posted by Janszoon (Post 1144748)
So you want to avoid talking about reality because there are some crazy people who get offended by it?

Yeah, pretty much most of the time - MB in a way is an exscape of reality for me.

Janszoon 01-22-2012 10:26 AM

Quote:

Originally Posted by Neapolitan (Post 1145072)
Yeah, pretty much most of the time - MB in a way is an exscape of reality for me.

*Waves to Neapolitan from the back of a giant blue dragon.*

Guybrush 01-22-2012 10:52 AM

Quote:

Originally Posted by Neapolitan (Post 1145072)
Instead of whole heartily agreeing with this experiment I think to myself isn't there something in this experiment that should had done differently. How about you are you totally fine with the proceedure? If there was something you would had done differently what would it be? Many experiments I hear of uses a placebo, maybe in this case a placebo should had been used. Say for instance have three unmarked vials give two scientist the brewer's yeast and the third scientist amoebae as a placebo and see if the same result of multi-cellularity would happen for all three or just the first two.

I think you misunderstand the point of having a placebo. When testing drugs, you use placebos because people taking drugs commonly have something called a placebo effect. What that means is that whenever someone takes a drug which is not very harmful, the drug should be expected to have a positive effect regardless of whether or not the chemicals in the drug actually have an effect. People's belief in medicine makes it work, even when it has no effect on it's own.

That makes it hard to test new drugs because when you see beneficial effects, you don't know whether it's caused by the drug or just the placebo effect. So, because of this, people partaking in medical experiments may recieve placebos (they don't know whether they get the placebo drug or the real drug). Then the effect on their health is registered. For a drug to pass such a test, it needs to have an effect which is significantly better than the placebo effect.


Needless to say, a placebo is not needed for this evolution experiment as there are no placebo effects going on here. They're not testing a drug. In my opinion, the experiment is just fine and I was actually impressed with how easy and elegant it was.

duga 01-22-2012 11:03 AM

Quote:

Originally Posted by tore (Post 1145081)
I was actually impressed with how easy and elegant it was.

Agreed.

Neapolitan 01-22-2012 09:41 PM

Quote:

Originally Posted by Janszoon (Post 1145074)
*Waves to Neapolitan from the back of a giant blue dragon.*

:wave: *waves back to blue dragon* http://msnsmileys.net/b/smileys/Bananas/Dragon.gif

Quote:

Originally Posted by tore (Post 1145081)
Needless to say, a placebo is not needed for this evolution experiment as there are no placebo effects going on here. They're not testing a drug.

In my opinion, the experiment is just fine and I was actually impressed with how easy and elegant it was.

Quote:

Originally Posted by duga (Post 1145083)
Agreed.

Yeah I guess we can agree that there's a sort of elegance to this experiment by how it was conduct with simplisticity, a few brewer's yeasts, an organically rich broth, and a vial to be shaken (not stirred) but imo the methodology of scientific endeavor is suspect. I guess I was expecting more information from what was going on behind the scene genetically. Like during the first stage of the experiment when the heavier yeast fell to the bottom presumably they were bi-cellular, was this an actual mutation taken place or alleles? And in the one of the final stages of the experiment those multi-cellular grouping (when they shook the vial some fell apart and the strong bounded multi-cellular yeast remain those other that fell apart) those that were loosely bound, was there specialization going on within the loosely bound multi-cellular group, because if there was why was there a specialization before a strong cellular bound that would keep them together as a multi-cellular organism?

duga 01-22-2012 09:56 PM

Quote:

Originally Posted by Neapolitan (Post 1145245)
Like during the first stage of the experiment when the heavier yeast fell to the bottom presumably they were bi-cellular, was this an actual mutation taken place or alleles?

A mutation results in the formation of a new allele of a gene that is already present. So any new genes that form and support multicellular yeast are alleles of genes that were present in the single cellular ones...they just now have a new function.

Neapolitan 01-23-2012 12:05 AM

What I was wondering was did the code for the propensity of multi-cellularity exist before or after the experiment started. Was there two traits or three traits that existed before the experiment started or did the mutations occur afterwards. That is why I said maybe it would had been better if they studied the genomes at each stage of the experiment to see what changes occurred. And even studied the singular cells a couple of generations down. My thought was there could point to a single cell 60 generations down and say hey look at this strain it mutated but that didn't cause multi-cellularity but look over here at this mutation (that differs from the ancestor cell) when this sequence started to appear that is when we first saw clumping etc. That's all. I guess I wanted more info than I saw in the article. The biggest concern it seem was that it appeared different but it didn't mention anything about the inner working of the DNA sequence.

Guybrush 01-23-2012 12:15 AM

Quote:

Originally Posted by Neapolitan (Post 1145245)
And in the one of the final stages of the experiment those multi-cellular grouping (when they shook the vial some fell apart and the strong bounded multi-cellular yeast remain those other that fell apart) those that were loosely bound, was there specialization going on within the loosely bound multi-cellular group, because if there was why was there a specialization before a strong cellular bound that would keep them together as a multi-cellular organism?

The clumps would likely be yeast cells that stuck together after reproduction. One cell buds off another cell and the two stick together because there's a stickyness to the surface, even on normal yeasts. Through evolution, that trait (as well as some others) was encouraged.

For reasons due to biological selfishsness, it is unlikely that more advanced multicellularity (with specialized cells doing different tasks) would evolve between unrelated yeasts. F.ex if you are a part of a multicellular machinery and have to sacrifice your own ability to reproduce, that could only have a fitness benefit as long as you did it in order to increase the fitness of those closely related to you.

Biological selfishness is a heavy topic to get into with someone who has not studied biology, but it is a highly interesting subject and for most who don't know it, learning about it would surely change their lives or at least the way in which they percieve life. Yet again, I recommend Richard Dawkins' popular classic The Selfish Gene.


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