Testing Evolution


(Nonlin Org) #1

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(Lynn Munter) #2

I very much appreciate your goal here. On the surface, it seems like a simple thing to achieve, right?

The problem is that even very small, rapidly reproducing organisms are not simple. I imagine your goal is to turn one variety of bacteria into something resembling another, very different variety of bacteria?

But how many generations have those two varieties been evolving for? Let’s say it’s been two million years. And each variety has had an average population size covering one ocean (this is a rough guess, but it will do) for those two million years.

How many bacteria generations is that, and how many bacteria in each generation? How many mutations does that many bacteria allow to be tried out, rearranged, and selected for or against?

And what is the best way for a modern lab to reproduce and condense that process?

Sure, a lab can artificially increase the mutation rate. But increase it too much, and now all your bacteria are dead. It turns out that the natural mutation rate is pretty well calibrated to allow mutations at a rate that gives good chances of coming up with useful tweaks but doesn’t change so much so fast that it’s deleterious to the organism.

So increase the population size, either by volume or by number of generations. Please let me know when you figure out how to equip a lab to match the total bacterial population of the history of the earth. I await this experiment on the edge of my seat.


(Nonlin Org) #3

You argue against laboratory testing in general. Are you sure you want to do that? At least Lenski and the others have not taken that position.


(Lynn Munter) #4

Do I? I’m just trying to explain why lab testing of bacteria cultures is unlikely to be able to reproduce billions of years of bacterial evolution under our microscopes. I’m not saying labs are bad or useless or can’t answer other interesting questions.


(Benjamin Kirk) #5

Lynn is doing nothing of the sort.