DARK BROWN HAIR WITH NATURAL HIGHLIGHTS
The two-gene model does not account for all possible shades of brown, blond, or red (for example, platinum blond versus dark blonde/light brown), nor does it explain why hair color sometimes darkens as a person ages. Several gene pairs control the light versus dark hair color in a cumulative effect. A person's genotype for a multifactorial trait can interact with environment to produce varying phenotypes (see quantitative trait locus). The other gene pair is a non-red/red pair, where the not-red allele (which suppresses production of pheomelanin) is dominant and the allele for red hair is recessive. A person with two copies of the red-haired allele will have red hair, but it will be either auburn or bright reddish orange depending on whether the first gene pair gives brown or blond hair, respectively. One phenotype (brown/blond) has a dominant brown allele and a recessive blond allele. A person with a brown allele will have brown hair; a person with no brown alleles will be blond. This explains why two brown-haired parents can produce a blond-haired child. The genetics of hair colors are not yet firmly established. According to one theory, at least two gene pairs control human hair color. Pheomelanin is more chemically stable than black eumelanin, but less chemically stable than brown eumelanin, so it breaks down more slowly when oxidized. This is why bleach gives darker hair a reddish tinge during the artificial coloring process. As the pheomelanin continues to break down, the hair will gradually become orange, then yellow, and finally white. Two types of pigment give hair its color: eumelanin and pheomelanin. Pheomelanin colors hair red. Eumelanin, which has two subtypes of black or brown, determines the darkness of the hair color. A low concentration of brown eumelanin results in blond hair, whereas a higher concentration of brown eumelanin will color the hair brown. High amounts of black eumelanin result in black hair, while low concentrations give gray hair. All humans have some pheomelanin in their hair. Particular hair colors are associated with ethnic groups. The shades of human hair color are assessed by Fischer–Saller scale. The Fischer–Saller scale, named after Eugen Fischer and Karl Saller, is used in physical anthropology and medicine to determine the shades of hair color. The scale uses the following designations: A (light blond), B to E (blond), F to L (blond), M to O (dark blond), P to T (brown), U to Y (dark brown/black) and Roman numerals I to IV (red) and V to VI (red blond). See also Martin–Schultz scale. Hair color is the pigmentation of hair follicles due to two types of melanin, eumelanin and pheomelanin. Generally, if more melanin is present, the color of the hair is darker; if less melanin is present, the hair is lighter. Levels of melanin can vary over time causing a person's hair color to change, and it is possible to have hair follicles of more than one color.
Popular Posts
-
More than the T- sentiment of K Chandrasekhar Rao, it is his tongue that is quite well known. Given his uncivilized vocabulary and a penchan...
-
images world map continents labeled. World+map+continents+ poorslumdog 09-04 12:20 PM Guys, Here is the list of people who recently died ...
-
Nagarjuna upcoming movie title was confirmed as Kedi (KD). KEDI is the title confirmed and makers announced the title in a special press mee...
-
images Ashley Tisdale long hair 2009- angs with long hair. long aamchimumbai 09-04 08:42 PM This is as per USCIC: 06/05/08. Previous edit...
-
images Taturday 64: Finger Tattoos! Shhh… on Twitpic Ramba 10-08 08:14 PM Once a person accepts employment using EAD, he/she gives up non-i...
-
This tattoo is koi fish tattoo is very liked by the Japanese. And Chinese people are also very fond of these koi fish tattoo.
-
Acharya Shree Koshalendraprasadji Maharaj (Ahmedabad) · Acharya Shree Rakeshraprasadji Maharaj (Vadtal) Vachanamrut · Shikshapatri · J...
-
images ABC of Sexually Transmitted transmitted infections) mzdial March 15th, 2004, 01:37 AM I'm guessing this topic was spurred by my p...
-
There is a news on TV9 Channel, that South Indian Actress Rambha getting married on 27th Dec'09 in Tirupathi. Not sure whether this a go...






