Evolution and the Second Law of Thermodynamics

I read an article following the debate between Bill Nye and Ken Ham titled 22 Messages From Creationists to People Who Believe in Evolution available at this link:


When I got to question 4 I scratched my head a bit. What does any law of thermodynamics have to do with evolution? None, I initially thought. But it seems in the comments section everyone is willing to answer it. So I am hoping to query the vast pool of knowledge here to ask what I am missing? Did the people fall for some kind of trolling bait or does the second law, or any law, of thermodynamics apply to evolution? Please help me out here if you can. Thank you for your time.

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Comment by Michael Penn on February 13, 2014 at 7:45am

DNA evolves and this is going on inside you as an individual even as you live. Living organisms are much like the farmer's wonderful ax that Dr. Clark is talking about. We think we are the same, but over time we are NOT the same. Constantly we are all "new and improved." Bad genes and cancer cells may show up sometimes, but every possible path that the DNA could take is not shown or present. Some paths are not even attempted. This is how "smart" this DNA building block really is.

This is why an ear of corn today is not the same as one in 1920. I suspect that todays human is much different than one from 1950, but you won't see that difference with your eyes. Similar ideas may explain why we will never find a "missing link." For things to evolve there need not always be a skeletal link. This is because every possible path is not taken. All there need be is TIME!

Comment by Jason Spicer on February 12, 2014 at 6:50pm

DNA evolves. Genes and interrelated groups of genes (sequences of ordered information) persist in DNA across generations of individuals. Sometimes new genes arise thru mutation and are retained or discarded by subsequent generations based on usefulness (or at least, lack of harm). DNA accumulates more and more ordered information via ratcheting mechanisms.

I think the creationists think that DNA should fall apart over successive generations, rather than accumulate useful information that can make more and more complex life forms. They think the 2nd Law means that only devolution is possible, not evolution. I don't know if that counts as a category error, but at minimum it means that creationists understand neither the 2nd Law of Thermodynamics nor evolution. I think the 2nd Law applies to, but is obviously not violated by, evolution.

A much better question is why do some "simpler" organisms (such as some salamanders) have way bigger genomes than "more complex" organisms (like humans)? I don't think this question dooms the Theory of Evolution, but at least it's kind of counterintuitive.


Comment by Luara on February 12, 2014 at 5:06pm

It's like the farmer's wonderful ax in which he replaced the head four times and the handle seven times, but always considered it the same ax.

Life itself is like that. The atoms in your body get replaced over time, and very few of them were there when you were a child. 

Evolution is change in properties of populations of organisms over time.

Yes, and the organisms have gradually become more complicated and more organized, which probably really does represent a decrease in their entropy density (entropy per unit mass). 

So I guess the basic answer to that creationist question is that living creatures export entropy, just like they export poop, breathe out, sweat, emanate heat, stir up the ground they walk on.  In what way does most of the entropy leave them?  is it mostly located in the poop, the heat, the disarrangement of the outside world?

Comment by Dr. Allan H. Clark on February 12, 2014 at 1:21pm

What is it that evolves? Not individuals of a given type or groups of individuals. Evolution is change in properties of populations of organisms over time. The changes are effected through selection so that the individual organisms gaining a modified attribute are not the same as the individuals without it.

Even if you try to define a physical system for each species as the collection of all individuals of that species at a given time, when you look at a later time, the collection consists of different individuals and cannot be considered from the point of view of physics as the same physical system.

It's like the farmer's wonderful ax in which he replaced the head four times and the handle seven times, but always considered it the same ax.

Comment by Luara on February 12, 2014 at 4:20am

ps Landauer's principle is that computers running irreversible computations - where information is lost - have to export that information as heat!  For example, if you "and" two bits together, the result is either 0 or 1.  But the two bits initially were in 4 possible states:  00, 10, 01, 11.  So if you throw away the values of those two bits, it's an irreversible computation. 

So there is a surprising connection between information and heat. 

Comment by Luara on February 12, 2014 at 3:56am

Creationists make a category error in applying thermodynamics to evolution.

How do you know that?

I was wondering that sort of thing - to what extent does our perception of meaning and organization and information content, relate to the physics definition of entropy?

Does a ton of bacteria have more entropy than a ton of people?  Probably. 

If your room is messy, does it have more entropy than if your room is neat?  Probably not. 

If your room is messy to the extent that everything in it is homogenized, and you allow the room-dust to settle, does that increase its entropy?  Yes. 

Life itself requires an entropy difference, so evolution by natural selection requires an entropy difference. 

Comment by Tom Sarbeck on February 11, 2014 at 8:53pm

The xians who make this category error do so because the many scientifically illiterate in their audiences hear it as a kick-in-the-stomach reply to those "pointy-headed scientists" who are destroying their god.

In short, it's an applause-winning line.


Comment by Dr. Allan H. Clark on February 11, 2014 at 5:46pm

Creationists make a category error in applying thermodynamics to evolution. The laws of thermodynamics apply to physical systems and the second law to adiabatically isolated physical systems. However, the evolutionary history of a species is not a physical system at all—it's an abstraction, an intellectual system organizing observable facts over many different physical systems, none of which are isolated. Thermodynamics just does not apply to abstract systems only to physical ones.

Comment by Luara on February 11, 2014 at 5:26pm

when you say "ideal heat engine", you're talking about an abstraction, correct?

It's a theoretical limit.  So the coolant being transported in the heat pump isn't perfectly insulated in its tubes, electrical wires have some resistance, etc.

Superconductors are supposed to have zero electrical resistance.  Maybe there will be quantum ideal heat pumps someday :)

Comment by Jason Spicer on February 11, 2014 at 4:20pm

Luara, thanks for adding to my understanding of the topic. Still, isn't it always the case that overall entropy in the universe is increased every time energy moves from one place to another? My understanding is that, overall, entropy increases (even though you can locally direct and store energy, which is why the creationist complaint makes no sense). So running your refrigerator costs some energy, even if it's doing useful work for you. In other words, when you say "ideal heat engine", you're talking about an abstraction, correct? Something that cannot be attained in practice? Or is this a technical term I don't understand?

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