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Misconceptions of Evolution IV March 30, 2009

Posted by Ian in Science.

Part four of my ongoing series discussing common misconceptions of evolution.  It starts here, and see part I, part II and part III.

6.  Like produces like

This one is an interesting misconception which operates on two levels. The first is the more common statement of the problem which is that dogs give birth to dogs, not giraffes. This is easy to refute since speciation is gradual and that species are not uniform, and I’ll refer the reader to parts II and III of this series for more discussion on this.   However it also reflects a deeper misconception about just what we are talking about when we talk about species and organisms in general.

As modern day thinkers we have built our understanding of biology via taxonomy. We divide all the animals into groups and understand their origins and evolution via their differences. We recognise a cat as being different to a dog because of the distinguishing features of the two species. This is a useful way to see things and is part of how we have come so far with biology to this day. Such differences are also a crucial aspect of why evolution works in the first place as differential survival depends on such variation.

This habit of thinking of the differences has one drawback however.  It tends to make us to overlook the fundamental similarities between organisms.  We think of cats and dogs as fundamentally different organisms and yet their similarities arguably outweigh their differences.  They are based on fundamentally the same DNA (just in a different arrangement), the body plan is very similar, and they exist for much the same purpose – making copies of themselves. 

The fact that all organisms are built around DNA really brings these similarities to light.  In a very real sense all organisms are really just variants of DNA molecules.  We can therefore take the question about organisms only producing their own kind and see that this is in fact exactly what happens: DNA molecules producing more DNA molecules. You don’t see a DNA molecule replicating into another type of molecule (at least not directly).  In this sense the part that matters hasn’t changed since DNA established itself.  Like keeps producing like, just in different arrangements.

I suggest reading The Making of the Fittest by Sean Carroll or River out of Eden by Richard Dawkins for more information.

7.  Evolution means organisms strive for fitness

This is a more obvious misconception but worth covering to continue building the picture.

There are a lot of explanations of evolution around that tend to use the lay language of organisms striving to fit into their environment (i.e. striving to be the fittest) as the basis for evolution.  However organisms have absolutely no control over their evolution whatsoever because they cannot control any of the fundamental drivers of evolution.  The only relevant part of an organism from the point of view of evolution is what genes it has and how likely it is within its environment to pass on those genes to the next generation.  Everything else is essentially filler.  We might think of it as important from a macroscopic point of view but evolution couldn’t care less what we think.

An organism is given its genes from its parents and has no mechanism to change them to the individuals advantage.  The genes it passes on to its offspring are a function of the genes it has plus any copying errors (mutations) that occur.  So the organism clearly has absolutely no control over the genetic side of things.  The other factor is the environment that organism finds itself in which in general the organism also has no control over.  Therefore the organism cannot strive to fit in better, it can only strive to survive.  Whether it does or not, and whether or not its genes live on, is a function of things well outside its control.

In fact it doesn’t take much to see that evolution operates quite happily without any conscious direction, striving, or otherwise.


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