The post can be found here; http://moultonlava.blogspot.co.uk/2005/11/all-about-redheads.html
It links hair colouration to the conditioning of the Fear Response.
"...breeding out wildness and breeding in tameness changes the body chemistry in such a way as to reduce the production of all the metabolic products of Phenylanine and Tyrosine, including Adrenalin, Dopamine, Serotonin, Oxytocin, and Melanin."Melanin is the pigment that turns your skin and hair dark.
The author further states;
"In humans, redheads are way over-represented in Math, Logic, Science, Philosophy, and Comedy ...Whyizzat? High levels of Adrenalin (Epinephrine) are associated with Athleticism and Anxiety. Low levels of Adrenalin are associated with Scholarship and Coolness. And one of the markers for that is the associated low levels of Melanin — e.g. redheadedness. "A fascinating theory. The author also links red hair to the 'Ninth Intelligence". More information on which can be found here;