Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum Report on a neat experiment

I'm not wanting to start a discussion on evolution or anything of the sort. I am reading "The Greatest Show on Earth" by Richard Dawkins. In it he describes an experiment run by Dr. Richard Lenski and his students. There is an account of it on Wikipedia.

In the experiment Dr. Lenski and his students started a long term experiment with e. coli bacteria. They set up 12 flasks of sterile water with nutrients and seeded them with the bacteria. Then every day they started 12 new flasks and seeded them with samples from the previous days flasks. They have been doing this since 1988. They track how well the bacteria do in each generation. During that time the bacteria in the various flasks have shown some adaptive changes that enabled them to do better than the initial population. Each day the bacteria multiply until they use up all of the main nutrient, primarily glucose, and then stop. Over time all 12 of the flasks showed increases in the number of total bacteria at the end of the day. However, some flasks did better than others. Apparently there were several strategies that the bacteria could use to improve survival rates and different lines adopted different strategies.

One line did something different though. It went along about with the others for a long time (around 30,000 generations) and then suddenly took off and had an enormous increase in the final population density. When they investigated it seems that the line had suddenly acquired the ability to metabolize citrate, which was also present among the nutrients. Normally e. coli. cannot metabolize citrates. So this was major evolutionary change.

I thought the whole experiment was fascinating. Day after day changing out the flasks and keeping the lines carefully segregated so that they could verify just what happened in each line. It is amazing what some scientists will do.

Bill Gill

That's quite something, Bill. Approaching quarter of a century of repetitive work. Has to say something about human patience, too.

1988

24 years.

I have a problem with this.

each day they set up 12 new flask.

is that 12 new flask or 12 cleaned flask?

normaly e-coli cannot metabolize citrates.

how did they determine that e-coli metabolized the citrates?

could the nutrients have been contaminated with a
element that would cause e-coli to metabolize the citrates?

has this experiment been replicated by other lab's?

have non biased scientist been in control of the experiment?

which strain of e-coli was used at the start in 1988?
which strain of e-coli was last noted in the experiment?

Could this quote from this week's "UK Safari" say anything relevant to the creation/evolution debate?

"Red-eared Terrapins were brought over here from United States for the pet trade. Remember the Mutant Ninja Turtle craze? When their owners found out how big they got, and how difficult they were to keep, many of those pet terrapins were let loose in ponds and lakes up and down the U.K.

They manage to survive our cold winters by sleeping at the bottom of ponds, and taking in oxygen by passing water over special membranes in the throat. It's thought that special sacs in the cloaca (rectal area) can also absorb oxygen!

It's incredible to think that while some humans are able to talk through their backsides these reptiles have actually evolved a method of breathing through them. Which begs the question, if a vet needed to resuscitate a pet terrapin with breathing difficulties... which end should get the kiss of life?"

No drawing comparisons with SAGG posters, please!!!

Good, relevant questions, Paul. I assume a full account of the experiment will be published somewhere.

Possibly the only one of your questions that would not answer would be: "have non biased scientist been in control of the experiment?"

which basically is the most important question.

would a scientist truthfully report evidence that reputes evolution , knowing that his career would be destroyed by the scientific community , and from that point onward he would
be considered a quack?

should we replace our scientist with machines that could not
possibly be biased due to beliefs.

this would remove any threat to a scientist career and standing in the SC.

then we have the problem of who programs the machine's that
render the experiments and their results.

do you see how the pot is boiling down and whats left in
the pot is belief system's?

[Quote=Mike Kremer]

Mike Kremer said, in reply to Paul.

Well it does look as though you do not have much faith in
human scientists, or is Richard Dawkins, the scientist himself?

That is what Scientists do, spend a large portion of their lives checking out the life cycles of Animals, Plants, and
Microbes etc.
Do you know who Mendel and the common Pea plant was?
Mendel was able to put Genetics on the map, through studying the flowers of peas for many generations.

Other Scientists have studied thousands of generations of
common Bread yeast, and kept and named the variety that they found developed into making the strongest alcohol before it died of self poisoning.

I myself would love to develop a food plant that could tolerate salt water.
By growing thousands of generations of a plant in increasigly salted water.
Unfortunately I could not possibly live that long to see my (feed the world food) idea come to fruition.

PS. You could prove the truth of Dawkins point by taking OUT
the Citrates from the viable Ecoli flask and watching his new species die off. QED.

Paul, it is very easy to test for citrate utilization, you grow the bacteria on a special agar with citrate as the carbon source and an indicator chemical that changes color when the citrate is metabolized. It is a simple test and yields results in a few hours. It is not dependent on, nor affected by, the presence of other nutrients or minerals in the growth medium. Normally E. coli does not have the ability to use citrate as a nutrient, so the development of citrate utilization is a novel trait. The fact that the ability to utilize citrate arose in one flask clearly points to a mutation as the source of the necessary enzymes to metabolize citrate. This is a clear example of evolution, no matter how you cut it.

Bill S. - You wondered if a report will be presented on the experiment. There are a number of links at the bottom of the Wiki article that will lead you to various reports on the subject.

Bill Gill

I don't see what difference that would make, as long as the flasks were sterile.


First what do you mean by non-biased scientists? And secondly reports in scientific journals have to pass peer review before they are published. As far as I know the journals have had no qualms about publishing the reports.

Basically most of your questions are ones that other scientists would also wonder about. So my understanding is that Lenski and his helpers were very careful in doing the work so that the results would not be contaminated.

Bill Gill

Possibly a good thing that the Church didn't realise the full significance of his discovery until after his death, by which time it was a bit late to silence him. I think the Catholic Church was still a little precious about the interpretation of Genesis in those days.

then evolution has been proven to be a fact correct?

or is it merely a possible example of evolution?

a biased scientist is someone who already know's that evolution is a fact , and not a theory.

E. coli long-term evolution experiment




peer review , mostly people who already know that evolution is a fact , and not a theory.


but lets consider this



24 years !
I thought that evolution required millions of years.

now it only requires 24 years !

what does that say about evolution?

people didn't eat tomatoes until recently.

does that say that we have recently evolved?

http://www.tomatogardeningguru.com/history.html

could it be simple environmental adaptation?

"...though they did think enough of the tomato to bring it back to Europe, where it was embraced long before we Americans succumbed to its charms."

Do non-Americans not count as people in your opinion?

you didn't read the article did you?

you think that humans have been around for millions of years
so whats a few hundreds of years?

isn't that recent?

I did read the article, which is why I was able to quote from it.

Perhaps you should be more specific when you use terms like recent. I assumed you were being true to your beliefs.

My mistake.

Well , to me a few hundred years is recent compared to 6000 years.