Recently several papers have been published related to entropy and evolution. According to Daniel F. Styer ("Entropy and evolution", Am. J. Phys 76, Nov 2008) and Emory F. Bunn ("Evolution and the second law of thermodynamics" Am. J. Phys 77, Oct 2009) entropy is decreasing due to evolution. Styer gives an estimate for the entropy change due to evolution, which is - 302 J/K per second. According to Styer and Bunn the decrease in entropy is not in conflict with the 2nd law of thermodynamics because Earth is "constantly absorbing sunlight resulting in an enormous increase in entropy." Bunn writes: "...the rate of entropy increase due to the Earth's absorption of sunlight must be sufficient to account for the rate of entropy decrease required for the evolution of life (a negative quantity)." According to Annila et al. [See eg. Vivek Sharma and Arto Annila, "Natural process - Natural selection," Biophys. Chem. 127, 123-128 (2007) ; Ville Kaila and Arto Annila, "Natural selection for least action," Proc. R. Soc. A 464, 3055-3070 (2008); Salla Jaakkola, Sedeer El-Showk and Arto Annila, "The driving force behind genomic diversity," Biophys. Chem. 134, 232-238 (2008)] entropy is increasing during evolution. Annila et al. writes: "There is no need to explain the rise of orderly structures by invoking an exemption that entropy would decrease in a living system at the expense of its surroundings. Entropy is increasing in living systems as well by dispersal of energy." "The primitive chemical evolution took the direction dS=dt > 0, just as the sophisticated evolution does today." "It is possible to deduce the direction of evolution and ensuing overall distribution of the genomic entities by requiring that S will increase until dS/dt = 0." "The rate of entropy increase can be regarded as a universal fitness criterion of natural selection." So, we have peer-reviewed papers that are making totally opposite claims. According to Styer&Bunn entropy is decreasing (a negative change) due to evolution and according to Annila et al. entropy is increasing (a positive change) due to evolution. The negative change of entropy due to evolution is also an important part of the argument presented by Styer&Bunn, because they use the increase in entropy due to Earth's absorption of sunlight to legitimate the claim that there is no conflict between evolution and the 2nd law of thermodynamics. And for Annila et al. entropy increase is an important part of the argument: “...entropy increase can be regarded as a universal fitness criterion of natural selection”. How is this controversy possible? We have a situation equal to a situation where some peer-reviewed papers would claim that gravity is pulling masses together while some other peer-reviewed papers would claim that gravity is pushing masses apart. What kind of science is this? Should we believe in Styer & Bunn and say that evolution is decreasing entropy or should we believe in Annila et. al and say that evolution is increasing entropy?
I think you're misunderstanding them. Both accept that the evolutionary process can decrease entropy in some manner. Firstly I should point out that there's no apriori reason to expect evolution to be a process which, overall, is an organising process. If conditions are such that natural selection favours less complex organisms then whatever criteria Styer et al. are using to quantify the entropy change due to evolution would return a positive value. Secondly, the entropy decrease due to evolution is negligable compared to the entropy decrease due to living organisms now. A plant will turn carbon dioxide and water into sugar, thus lowering the entropy of those chemicals, all the time and this is much much more than any entropy decrease which might ensue from it having offspring with slightly more elaborate petals or leaves. In either case, the decrease in entropy is provided by the Sun, either directly or indirectly, and while local decreases in entropy occur they are more than offset by the increases elsewhere. The Sun provides low entropy energy but at the expense of vast quantities of entropy within itself. Yes, the genes of animals might have lower entropy, just like the sugar chemicals end up with lower entropy, but it costs much much more entropy overall. Local decreases in entropy are not a problem. Cleaning your house decreases the entropy of its contents but you expend energy and entropy doing it. There's no violation of thermodynamics, it has cost you a lot of energy to move things around so that the entropy of part of a system is decreased. In expending that energy you produced much much more entropy and so overall the entropy of your house, including you, is increased. It costs energy to low entropy and that energy cost is also an entropy cost. No problem at all.
This is a very good thread, here are the citations in links. http://arxiv.org/pdf/0903.4603v1 http://www.swarmagents.cn/thesis/doc/jake_230.pdf I would love to read both of them when I have time and reply with a proper response. The latter seems to model evolution in a manner I find very interesting, a few years back I had to make a best fit program for a density landscape, so I have some understanding with that kind of topic.
This is only your view. Styer and Bunn only state that entropy is decreasing due to evolution. They do not state the opposite.
I am sure that its possible for the evolution of a particular species to end up with a negative entropy value. For instance, I'm white. I'm certain if you go far enough back my ancestors were black and living in Africa. I have lost the gene which produces the pigment in my skin which would make me black. I have blue eyes, which is a lack of a pigment in my eyes, and means I lack the gene to give me eye colour because it expresses itself over the blue eye gene so someone with both brown and blue eye genes will be brown eyed. If there were some natural selection reason which made blue eyes and white skin advantagous over other combinations it would mean evolution leads to a lose of those genes and a reduction in part of the genome complexity. Yes, I agree that its overwhelmingly more likely for evolution to introduce new things to genomes and increase 'genetic memory', where old genes are still kept around, but it would seem to me that its not impossible for evolution to also go the opposite way if the right circumstances were to arise.
The Earth isn't a closed system. The decrease in entropy as a result of evolution is therefore dwarfed by the increasing entropy in the universe as a whole.
Bunn wasn't attempting to calculate the actual entropy change involved in life evolving, he was trying to calculate a maximum possible upper bound for the magnitude of entropy decrease that could occur because of evolution. He did so in order to show that energy influx from the sun could more than account for any entropy decrease that could plausibly be caused by evolution. In other words, Bunn said "Evolution couldn't possibly have decrease the Earth's entropy by more than this amount." He isn't attempting to argue that evolution actually causes a net decrease in entropy.
Entropy-evolution nonsense The two have nothing or very little to do with each other and trying to combine the two in the same argument in my view shows a weak or no understanding of either or both. Entropy which applies to a closed system - like the universe - is an important concept in thermodynamics (the action of heat) which basically states, you can't win, you can't even break even. Evolution is a natural process by which populations adjust genetically to best survive in and procreate in their environment. In the process of evolving - that is adapting to changes in the environment - organisms may ( and probably do) make genetic choices leading to the minimal, or most efficient use of energy. That's not entropy. In fact its the opposite, its the conservation of energy. A cat lying down at rest isn't producing entropy other than by normal at rest biologic processes for you nit pickers. When it pounces it then produced (extra ) entropy, a bit of heat never to be recovered. Please Register or Log in to view the hidden image!
Life itself has been succinctly defined as "a local reversal of entropy." So what's the surprise if the processes in which life is involved, like evolution, are also local reversals of entropy?
Mod note: Posts about hitherto unbuilt mystical machines that “reverse the entropy of closed systems”, fairytales offered as supporting evidence and associated replies, have been moved to a separate thread in Pseudoscience ("supposedly reversing the entropy of closed systems").
The two papers appear to be talking about different systems - differently bounded regions or areas within which the entropy change is to be calculated. I have no access to the original papers, but the quotes posted from the second one (Annila et al) confuse me. What are they talking about by "genomic entities"?
