At 15:44 22.07.03 +0000, John wrote:

>Genetically the situation is complex. Hair colour is a matter of
>melanin synthesis pathway. Generally there are two types of melanin
>present eumelanins and pheomelanins. The eumelanin is black in
>colour and made from processing the amino acid tyrosine into dopa and
>dopamine in the presence of tyrosinase, and then joining a number of
>these chains together to form the eumelanin. Generally eumalinin is
>brown (with 2 polypeptide chains and a COOH acid radical), but with
>more tyrosinase present it will be dark black in colour (with 3
>polypeptide chains).

Just for curiosity's sake: is the percentage of tyrosinase then what makes
the difference between types of black hair that display a reddish vs. a
blueish shimmer when held against the light? Or what else is responsible
for these (sub -?) types?

Thanks in advance.

Best,

Heike