Hair Color: Traits and Genes

Hair Color: Traits and GenesKT Leitl

Basic Facts of Human Hair• Genes in hair color aren’t fully established.• Theory – At least two gene pairs control human

hair color• Two pigments for hair color: Eumelanin and

Pheomelanin

Eumelanin• Eumelanin – The two subtypes determine the

darkness• Black – High counts lead to blacker hair, lower counts

result in gray hair• Brown

Pheomelanin• Pheomelanin - is

generally makes red

Phenotypes• Brown/Blonde• Brown – Dominant allele• Blonde – Recessive allele

• Non-red/Red• Non-red – Dominant

(suppresses pheomelanin• Red - Reccessive

Brown Hair (Brunettes)

• Higher levels of (brown) eumelanin

• Lower levels of pheomelanin

• Medium to thick hairstrands

Black Hair

• Most common• Ranging from soft

black, blue-black, and jet black

• Lots of eumelanin• Less dense color

Blonde Hair

• Platinum blonde, dark blonde, strawberry blonde (most rare and contains the most pheomelanin)

• Only small amounts of pheomelanin and eumelanin (more creates ash blonde)

• Most blondes get darker with age

Auburn Hair

• Ranges from light to dark red-brown

• Eumelanin (brown)• Pheomelanin (red)

Chestnut Hair

• Red-ish shade of brown

• Darker than auburn

Red Hair• Least common• Light strawberry, titan

vivid orange, copper, “true red” (least common)

• Caused by Mc1r (recessive)

• 67% pheomelanin• Lowest levels of

eumelanin• Most common in Scotland

(13% are, 40% carry the recessive gene)

Grey and White Hair

• No actual pigment• Clear hair• Lack of pigment

and melanin• Color based on light

reflection• Generally in people

of age• As early as ten

Gender In Hair

Men• Generally black of dark

hair

Women• Red and blond hair

Works Cited• En.wikipedia.org/wiki/Human_hair_color • Google images