They suggest that either environmental or sexual selective pressure began acting on hair after humans began dispersing out of Africa, helping shape the wide range of human hair types present today. The limited evidence points to temperature as a factor. Curly hair may help keep the head cool in warm climates.
The story of human migration and evolution is written in hair DNA. In sub-Saharan Africa, genes favour tight, curly hair. But in east Asia, mutations have led to straighter, thicker hair. In Europe, other mutations brought wavy and straw-coloured hair.
It is associated with the newly emerged alleles in both the TCHH gene and EDAR gene. 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.
Curly hair is thought to be better at keeping mammals warmer than just straight hair alone. In fact, straight hairs interwoven with curls creates the last line of defense against heat loss.
Puberty, menopause and pregnancy all cause hormonal shifts that can make your tresses go from straight to curly hair. In fact, 40-50% of women experience major changes in their hair while pregnant or breastfeeding. In fact, one of those women was one of the founders of Royal Locks.
Less than 20% of people have naturally curly hair. The percentage gets even smaller when you consider the scores of guys out there who don't embrace their curls.
Lots of traits are statistically rare: Left-handedness (just 10 percent of the population!), curly hair (11 percent!), and blond hair (4 percent!), to name a few.
Many Asians have naturally straight hair, but there is a significant group of us who do have naturally curly or wavy hair! However, because it's the norm to see straight and sleek hair, curly haired boys and girls tend to think that their hair is some kind of unruly straight hair that isn't behaving.
Curly hair is considered a “dominant” gene trait. Straight hair is considered “recessive.” To put that in simple terms, that means that if one parent gives you a curly-haired gene and the other parent gives you a straight-haired gene, you'll be born with curly hair.
In fact, more people prefer curly hair to straight hair. Though beauty is seen differently by everyone, one thing is for sure; curly hair is getting a lot of love lately. In fact, in a survey conducted by StyleCaster, a surprising 58% of guys thought curly hair was sexier than other hair textures.
Caucasian hair can be smooth, wavy or curly.
From genotyping results, European hair shape varies mostly between wavy (46.6%) and straight (40.7%), with some curly hair (12.7%) (n = 2138) [10]. The same study showed that Asian (East and West) hair shape is also mostly straight (46.7%) or wavy (41.3%), with some curly hair (12%) (n = 92).
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.
Alleles, which can be recessive or dominant, is the part of your genetic code that determines hair type, and how we look. Curly hair is a dominant trait. So if one parent has curly hair and the other straight, it is more much likely that their offspring will have curly hair.
Follicles that are more oval in shape cause curlier hair to grow. Very tightly coiled hair is due to the nearly flat, ribbon-like structure of their follicles. This hair texture is very common in people of African ancestry. Not only is African hair often coiled, it also has a unique texture.
Curly hair or fur is extremely rare among wild animals. Generally, only domesticated animals have curls, and those that do have been selectively bred by humans to promote a curly coat, including the poodle and the sheep, perhaps the two most iconic curly animals.
Hair morphology is one of the more conspicuous features of human variation and is particularly diverse among people of European ancestry, for which around 45% of individuals have straight hair, 40% have wavy hair, and 15% have curly hair.
Lots of traits are statistically rare: Left-handedness (just 10 percent of the population!), curly hair (11 percent!), and blond hair (4 percent!), to name a few.
This means two things: 1) if a person carries one allele for curly hair and another for straight hair, this person will have curly hair; 2) curly hair is a simple trait and is most likely determined by one single gene.
Curly hair is not certain to a race or ethnicity, it appears all over the world in many forms. White, brown, black and everything inbetween! There is also a scale on which curly hair is classified (2a-4c).
There are plenty of blue-eyed Asians. This probably happens when the traditional blue-eyed allele comes into a family from a (possibly very distant) European ancestor. Blue eyes then resurface in a child generations later if they inherit the allele from both parents.
Evolutionary trait
It is known that 45% of European people have straight hair, 40% have wavy hair and 15% have curly hair. They had previously established the heritability of curly hair, finding there was as much as a 90% chance of it being an inherited trait.
Hair type 1A is super-straight. It doesn't even hold a curl! 1A is the rarest hair type. It is usually found on people of Asian descent.
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.
Curly hair has a history of being seen as "messy" or "unruly". According to stereotypes and media, "proper" or "attractive" people don't have curly hair. Curly hair is often described as "messy looking", as it's harder to keep tied up and harder to shape into a completely symmetrical style than straight hair.