It has been reported that Asian hair is generally straight and is the thickest, while its cross-section is the most round-shaped among these three. Caucasian hair is generally straight or wavy and is the thinnest, while its cross-section is relatively elliptic.
The distributions of these straight hair related alleles (see figure) support the hypothesis that our human ancestors had curly hair; the straight hair found in East Asians and Caucasians likely developed independently.
Hair type and texture are determined by several factors, including genetics. The African hair is more coiled and drier; Asian hair (Korean, Japanese) is straighter and thicker; and Caucasian hair is somewhere in between with around 45% having straight hair, 40% having wavy hair, and 15% having curly hair.
Type 1: Straight Hair
Type 1A hair is very straight and fine, with no hint of wave or curl. As it is so straight and fine, when the natural oils travel to the ends, it tends to cause it to look like oily hair. It is the rarest hair type and is common among women of Asian descent.
People from countries like Japan, China and Korea tend to have mostly straight hair, while Africans have curly hair and Europeans are mostly a mixed bag.
Nearly 80% of Asians either have naturally straight hair or have styled it that way or they born with it. Straight hair is what is referred to as “Type 1” hair.
The average diameter, or thickness, of Asian hair is from 80 to 120 µm, compared to 65 µm in Caucasian hair and 55 µm in Black hair. The average diameter of Hispanic/Latino hair tends to fall between that of Asian and Caucasian. Caucasians have the highest hair density among the ethnicities studied.
We believe one of the reasons is that super-straight hair — also known as type 1a hair — is so rare. In fact, it's the rarest hair type. Only 2% of the world's population has 1a hair. It's mostly found in people of Asian descent.
Hair type 1A is super-straight. It doesn't even hold a curl! 1A is the rarest hair type.
A general observation across experiments was that straight hair was perceived as younger, healthier, and more attractive than wavy hair and darker shades (medium copper and brown) were perceived more positively than blonde hair.
The rarest natural hair colour is red, which makes up only one to two percent of the global population. You commonly see these hair colours in western and northern areas of Europe, especially Scotland and Ireland. However, natural redheads may not exist for much longer.
Genetic factors appear to play a major role in determining hair texture—straight, wavy, or curly—and the thickness of individual strands of hair. Studies suggest that different genes influence hair texture and thickness in people of different ethnic backgrounds.
Caucasian hair usually appears thicker since it is more difficult to see through the scalp than other ethnic hair types. However, Asian hair is the thickest and coarsest hair of any ethnic group.
Straightening hair dates back as far as ancient Egypt, where flat iron plates were used to straighten unruly hair.
Caucasian hair can be smooth, wavy or curly. Its colorimetry can vary from blond to dark brown. It grows obliquely, and grows about 1.2 centimeters per month.
Type 2: Wavy Hair – This hair type is common among people of mixed-race and some Europeans. Wavy hair has a slight S-shaped wave pattern and is thicker than straight hair. Type 3: Curly Hair – This hair type is common among people of African descent, but can also be found in other ethnic groups.
The least common hair type, 1A hair is extremely fine and perfectly straight. Consequently, it can look a bit flat and limp and might prove difficult to style. Dry shampoo can be your ally in the fight against excessive oil and thick hair products that might weigh your hair down are best avoided.
Most women think brunette hair is the sexiest, as 25% of those polled favoured this option. Womens' second preference is blonde, which was voted as the sexiest hair colour by 19.6% of women. Again, red took third spot, accounting for 11.8% of womens' votes.
How common is strawberry blonde hair? Having natural red hair is rare (like, two percent of the population rare), so coming across someone with natural strawberry blonde hair isn't common.
Thick (Coarse)
Thick or coarse hair texture is the strongest hair texture and typically feels coarse or thick to the touch. Coarse hair contains all three hair layers – the cortex, cuticle and medulla.
The rarest skin color in the world is believed to be the white from albinism, a genetic mutation that causes a lack of melanin production in the human body. Albinism affects 1 in every 3,000 to 20,000 people.
There are racial differences, however, in the incidence of male pattern baldness. The highest rates are found among Caucasians, followed by Afro-Caribbeans. Chinese and Japanese men have the lowest rates. For some unknown reason, this form of hair loss is does not occur among Native Americans.
Individuals of African ancestry, for example, are more likely to have curly hair due to the oval shape of their hair follicles. Additionally, the Keratin Associated Protein (KAP) cluster genes, responsible for the structure of keratin fibers, have been found to have variations in many African populations.
Genetics (which controls ethnicity) is the number one cause of hair loss. Certain races have higher rates of hair loss compared to others. Caucasians have the highest rates out of all the ethnic groups. On the opposite end of the spectrum, Native American Indians, Inuits, and Chinese have the lowest rates.