[Taxacom] Blue eyes in humans

[jadams at daltonstate.edu]

Ken, et al,

Ken wrote:
>  But however one defines
> "blue eyes", their frequency has clearly been decreasing in frequency
> over the last century.  Even in the U.S., it has decreased from 
> about a bit over 50% around 1900 to less than 20% today.

Really?  News to me (I haven't kept up on eye color literature [is there eye
color literature?]), though the immigration information makes some sense.  It
may interest you to know that every semester in my Biology/A&P classes, just to
make a point about "recessive" vs. "rare", I ask my class members to raise their
hands if they have blue eyes, and NOT ONCE in 21 years of teaching have I NOT
had a majority of blue eyed people in my class (occasionally up to 80%). 
Clearly, this involves some regional influence (I'm in rather rural NW Georgia),
but I was unaware that blue eyes were below 20% in the U.S. and find this almost
hard to believe.
      
>      Given the recessive nature of blue eyes (and by extension, 
> green, grey, and various mixtures thereof), should one expect the 
> 20th Century trend (decrease) to continue,

There is no way that this follows.  With the understanding, as I indicated
above, that recessive does NOT mean rare, unless there is some selective force
working to drive the blue color down (though the emigration of non-blue eyed
people certainly plays a minor role in changing frequencies), there is no
necessary connection between the recessive nature of blue eyes and this allele
becoming rarer.

Just my two cents.

James


James K. Adams
Professor of Biology, Dalton State College
706-272-4427; 678-767-5938
Check out Georgia Lepidoptera at:
  http://www.daltonstate.edu/galeps