Natural selection may not produce the best organisms

"Survival of the fittest" is the catch phrase of evolution by natural selection. While natural selection favors the most fit organisms around, evolutionary biologists have long wondered whether this leads to the best possible organisms in the long run.

A team of researchers at The University of Texas at Austin, led by Drs. Matthew Cowperthwaite and Lauren Ancel Meyers, has developed a new theory, which suggests that life may not always be optimal. The results of this study appear July 18th in the open-access journal PLoS Computational Biology.

Genetic mutations create the raw material that natural selection acts upon. The short-term fate of a mutation is often quite clear. Mutations that make organisms more fit tend to persist through generations, while harmful mutations tend to die off with the organisms that possess them. The long-term consequences of mutations, however, are not well understood by evolutionary biologists. The researchers have shown that what may be good in the short run, may hinder evolution in the long run.

The team developed computer models of RNA molecules evolving by mutation and natural selection. RNA molecules, which are very similar to DNA, play key roles in essential life processes and serve as the genetic material for some of our deadliest viruses, including influenza and HIV.

Their computer models show that the evolution of optimal organisms often requires a long sequence of interacting mutations, each arising by chance and surviving natural selection. As Cowperthwaite explains, "Some traits are easy to evolve – formed by many different combinations of mutations. Others are hard to evolve – made from an unlikely genetic recipe. Evolution gives us the easy ones, even when they are not the best."

The group's analysis of RNA molecules from a wide variety of species suggests that life is indeed dominated by the "easy" traits, perhaps at the expense of the best ones.

Citation: Cowperthwaite MC, Economo EP, Harcombe WR, Miller EL, Ancel Meyers L (2008) The Ascent of the Abundant: How Mutational Networks Constrain Evolution. PLoS Comput Biol 4(7): e1000110. doi:10.1371/journal.pcbi.1000110

Source: Public Library of Science

   

• JerryPark - Jul 18, 2008
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  Perhaps the phrase should be 'survival of the fit enough'?
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• ancible - Jul 18, 2008
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  How about this? Factor in the difficulty for a blind system (evolution) to achieve the more fit organisms and it can be seen that a simple, second-best organism IS more fit than a more specialized/complicated/very unlikely organism due to it's being more likely to evolve.
  
  Kinda like how one could make the case that gas powered cars are more fit due to lower tech demands than hydrogen ones...
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• D666 - Jul 18, 2008
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  In what possible way is this new news? Gould wrote a book around this megayears ago called "The Panda's Thumb" (IMS). Sometimes I wonder about science reporting when they recycle old news based on some new detail. In this case, I think the only "new news" is a new computer model. Big whoop.
  
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• Valentiinro - Jul 18, 2008
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  Luckily, evolution has produced a creature with the characteristic of being smart enough to modify genes, so we don't have to worry about this natural selection thing anymore. Yay.
  
  Unless the "more fit" but harder to evolve creature did get around to evolving, mr. average joe fitness would still have his niche to live in. Nobody said evolution produces the best organisms, but the best in the area at whatever it is they do tend to reproduce the most by definition of what life does.
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• PJS - Jul 18, 2008
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  What does "best" mean? That's a completely subjective term. What kind of scientists are these?
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• Quantum_Conundrum - Jul 18, 2008
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  What does "best" mean? That's a completely subjective term. What kind of scientists are these?

  
  
  
  Technicly true.
  
  If you are in the ocean, "Best" will be completely different than on land.
  
  If you are in the arctic, "best" will be compltely different than in the desert at the equator.
  
  Additionally, if you've just had a meteor impact, "best" is completely different than a normal year.
  
  
  
  "Survival of the fittest" is actually a complete misnomer, since a superior species on one continent or island can be irradicated by a disaster due to proximity, while an inferior species with a similar niche might survive on another continent or island.
  
  
  
  Evolution is a theory of luck and mutation, and has nothing whatsoever to do with which species is the "best", nor does it even really attempt to define what "best" is.
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• D666 - Jul 18, 2008
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  "Best" has one simple definition in this context: best able to survive and reproduce given current conditions. If conditions change abruptly, so does "Best". If a species is getting out-competed in their current niche by some other better species, then the "best" members of the first group are those that can find a new niche - and fast.
  
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• nilbud - Jul 18, 2008
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  It's not "survival of the fittest" it's the "slaughter of everything not 'fit'".
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• superhuman - Jul 19, 2008
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  Its obvious that evolution wont ever produce 'best possible organisms' to anyone who understands the concept.
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• menkaur - Jul 19, 2008
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  define "best"....
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• DoctorKnowledge - Jul 19, 2008
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  "Best" really isn't an appropriate scientific word -- as people have been pointing out -- in a context where "best" might mean any number of things.
  
  Is a species of tree that survives 100,000,000 years *overall* better than one that survives 99,000,000? We should just write off that "lesser" tree as a failure? The human race will be lucky to survive that long!
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• ancible - Jul 19, 2008
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  superhuman:
  

  Its obvious that evolution wont ever produce 'best possible organisms' to anyone who understands the concept.

  
  
  DoctorKnowledge:

  "Best" really isn't an appropriate scientific word...

  
  
  A polite disagreement: I think best can be effectively defined here because it is attached to the concept of "evolution by natural selection". Hence the organism with the greatest ability to pass on it's genes. Though granted, "best" in the abstract is quite ephemeral.
  
  edit: sorry d666, didn't see your post. You beat me to the punch.
  
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• superhuman - Jul 20, 2008
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  Yeah, "Best" can be defined since evolution can be seen as an optimization of a set of parameters so as to maximize reproductive success. Now we can go two ways and define "momentarily best" or "absolutely best" by wanting success to be maximal at a certain point in time or the integral of success during a time period to be maximal, for example during the existence of the species.
  
  The chance that evolution will produce either one is infinitesimal due to its random nature and the immense volume of parameter landscape.
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• KB6 - Jul 21, 2008
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  DoctorKnowledge said:
  "The human race will be lucky to survive that long!"
  --
  True, the human race probably won't. But the human line of descendants might.
  And they will no longer be human.
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• D666 - Jul 21, 2008
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  Define "human" :-)
  
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• thales - Jul 21, 2008
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  My college management prof taught that when faced with multiple alternatives to a solution, one can either seek to optimize - find the absolutely best solution - or "satisfice". Satisficing basically means finding the best solution given a restricted amount of resources (i.e. time) that can be devoted to researching alternatives.
  http://en.wikiped...isficing
  
  Evolution satisfices rather than optimizes.
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• KB6 - Jul 21, 2008
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  Define "human" :-)
  ---
  Ultimately, it's whatever we want it to be - within the laws of physics, of course.
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