Perhaps there was sexual selection once environment got the ball rolling.

Blue- Eyed Men Prefer Blue-Eyed Women

Perhaps there was sexual selection once environment got the ball rolling.

perhaps. though the paper's purported reasoning, paternity, seems rather weak. after all, once frequency gets high the selective benefit is low when almost everyone has blue eyes.

...third longest haplotype in the European genome.

I don't understand that. Third oldest? Third most selected for?

Is there a connection between blue eyes and seasonal affective disorder? It seems of the girls I've known with it, most had blue eyes.

Rob,

Length of haplotype is a proxy for strength of selection.

Re: SAD, you're bumping up against one of my current areas of research.

http://ajpregu.physiology.org/cg...act/292/6/ R2352

"The percentage of suppression of melatonin secretion 2 h after the start of light exposure was significantly larger in light-eyed Caucasians (88.9 ± 4.2%) than in dark-eyed Asians (73.4 ± 20.0%) (P < 0.01)."

If you believe the "excessive melatonin" theory of SAD, then this points in the opposite direction.

Maybe I didn't know a representative sample then. But what about dark-eyed Caucasians v. light-eyed Caucasians?

I've often wondered if SAD was an adaptation to long , dark, cold winters. Sort of mild hibernation.

How often does SAD occur in people whose ancestors came from more equatorial regions?

If it's really a pathological state, I would expect people who lived for generations in places with long, dark winters would be more resistant than people who didn't. But if it's an adaptation that we now regard as inconvenient or wrong, it would be far more common in people bred for those regions. It would also be very rare in equatorially-ancestored people who now lived in dark winter regions.

Interesting. I assumed that the blue color allele affected skin color only in the homozygous state.

At the risk of quibbling, wouldn’t some of this linkage be an artefact of geographical association? The authors state that the authors were over 95% of northern European origin, most being Anglo-Celtic. But even in the British Isles, both eye color and skin color vary geographically, with people from Wales and southeast England being noticeably darker. Is this genetic linkage or is it simply a geographical association much like what we see between northern and southern Europe.

.At the risk of quibbling, wouldn’t some of this linkage be an artefact of geographical association?

i'd bet on it. this is probably a higher bound. that being said, OCA2 does cause albinism, so there is a strong a priori assumption that it can physiologically affect skin color.

Humans carried not much more than a hand axe for a million years or so and suddenly in the last 40000 years advanced to flying in space. This suggest a genetic change in the brain that spread rapidly in the population has allowed greater technology and easier survival even in the face of an iceage. All the other genetic peculiarities are just along for the ride.