Whilst half-watching the Hairy Bikers and knitting a polar bear tonight I learned that everyone with blue eyes is descended from a common ancestor who lived between 7,000 and 10,000 years ago. This led me to the Internet and to this post – the contents of which definitely predate 1066 but I was fascinated by what I read even if it turns out to be old news much of the material i read dated from 2008.
Apparently, according to the University of Denmark once upon a time everyone had brown eyes. Then a gene mutated. A couple or so generations later and bingo – blue eyes. How do we know this? Essentially the study looked at the genes of folk with blue eyes in Denmark and then expanded their study across the globe. They had expected the gene responsible for eye colouring to be similar in all their blue-eyed samples but they weren’t just similar they were identical. The gene is called HERC2. This not only means that somewhere along the line that everyone with blue eyes is related but that because the mutation hasn’t changed at all its still fairly recent – ten thousand years (the end of the last ice age) is recent in gene terms. Further study has revealed that blue eyes must have originated somewhere in the Balkans as this is where most people have blue eyes – 99%, dropping to 75% in Germany.
I had to dig deep into my memories of school biology lessons but essentialy if I’ve remembered right we have two sets of genes – one from each parent. Brown eyes are the dominant colour so in order to have blue eyes (blue being the recessive gene) you need to have been given a matching pair of blue genes (that may be a very bad pun but I know what I mean) by each parent hence the first person with the mutation didn’t have blue eyes and nor did their children. The blue eyes would have occurred when two people carrying the recessive blue gene both gave that particular gene to their child.
A prehistoric skeleton unearthed in Spain in 2006 and written about extensively in Nature is recorded as the ‘first’ blue-eyed person. The Independent also notes that the man had lactose-intolerant genes, which means that he lived before the period when farming had become a normal way of life. It must have been pretty startling for the Mesolithic man’s parents when they produced a baby who had eyes that were blue rather than brown like everybody else’s.
There are two theories as to why blue eyes spread through the population – the first is that blue-eyed Mesolithic man was hot-stuff and consequentially there was a rash of blue eyed babies who in their turn went on to have many blue-eyed babies. More prosaically there is a theory that the gene which produces blue eyes also helped to prevent eye disease in cold dark northern climates because, very simplistically, blue eyes contain less melanin so let more light in.
Just to finish on a note that draws me firmly post-1066- analysis of King Richard III’s skeleton revealed him to be blue eyed (and probably blond in his childhood) which means that if like me you have blue eyes you can claim to be very distantly vaguely related to him. Equally, you can also claim to be related to Cameron Diaz and Frank Sinatra.
http://www.livescience.com/9578-common-ancestor-blue-eyes.html (accessed 6/10/2015@22:41)