Expert: Dana Krempels, Ph.D. - 5/15/2007

Question
Dear Dana,

I am a Ph.D. Psychology student in Germany, and I am extremely interested in how biological evolution and adaptation processes work.

According to what I have read about "Selfish Gene Theory", adaptations are the phenotypic effects of genes, in order to maximize their representation in the future generations. According to this, an adaptation is maintained by selection if it promotes genetic survival directly or some subordinate goal that ultimately contributes to successful reproduction.

My questions are:

First of all, how much scientific evidence this theory has, and how is this theory viewed in the scientific community?

Can these phenotypic changes be inherited by next generations? And if so, how nucleic acids could be altered by external conditions?

Best regards,

Jeffrey  

Answer
Dear Jeffrey,

Richard Dawkins is nothing if not controversial!  His work has provoked a great deal of support, as well as derision--but no one can say that he hasn't crafted exquisite arguments for his ideas about selfish genes.

The scientific evidence existing to support his ideas are just the mechanisms of evolution of natural selection that we can observe in the daily world.  I do not think it is possible to quantify the survival of "selfish genes" simply because if a gene has made it into this generation...it's a survivor and could be hypothesized to have gotten here via "selfish" means of making something in the phenotype adaptive.

The main problem with Dawkins' hypothesis was put forward by the eminent evolutionary biologist, Stephen Jay Gould (whose work I would *highly* recommend if you are interested in any aspect of evolution).  He disagreed with Dawkins, pointing out that natural selection occurs, not at the level of the gene, but at the level of the whole organism.  Hence, many "inferior" genes might be taken along for the ride into the next generation without having to affect the phenotype at all.  In an ever-changing environment where selective factors are labile, it is difficult to predict which genes will be adaptive from one generation to the next.  This presents a problem for the "selfish gene".

Gould's argument might be the most powerful one against Dawkins' hypothesis, but I believe it's still possible that both mechanisms are at work.

The scientific community generally has great respect for Dawkins' intellect, and some of our faculty even use his books (The Selfish Gene; The God Delusion) in their seminar courses, even if only to promote discussion and argument.  In other words, he is by no means considered a crackpot.  One has only to listen to him speak to know that this is a man of tremendous intellect and scientific creativity whose ability to engage in high-level critical analysis is unquestionable.

Finally, to answer whether phenotypic changes can be inherited by subsequent generations:  it depends.  Many genes affect phenotypic traits in combination with other genes.  Environmental influence during development (as early as the first few days after fertilization) can also affect the way genes are expressed--and in ways we do not fully understand.  That's why this is so difficult to study.  As in many areas of biology (and psychology!), there are so many variable that one cannot hope to control only one and see the outcome.

DNA can be altered between generations by more than just point mutations.  There can be changes in the way certain genes are "packaged," making them more or less likely to be expressed, or for their products to be expressed in lower quantity, thus affecting phenotype.  There can be transpositions of genes that act in similar ways.  So even if a "selfish gene" is passed to the next generation, there may be no guarantee that it will behave in the new organism the same way that it did in the parent.

Whew!  When I signed up to answer Biology questions a week or so ago, I had no idea I'd be getting such interesting and provocative questions!  Fun!  

I hope this has helped a little, and that some of the above may even be intelligible.  But please write back if you think I need to clarify any of the above.

Good luck with your dissertation!

Dana