Research groups from Brazil and USA have recently discovered a new layer in human hair.
A layer of beta keratin between the cortex (inner) and cuticle (outer) layer of the hair shaft was discovered by Vesna Stanic and colleagues.
They presented their findings at the 2015 Annual Meeting of the American Crystallographic Association in July 2015, in Philadelphia, Pennsylvania.
Their finding raises interesting questions about hair function and Neanderthal inheritance.
Beta-keratin was usually associated with reptiles and birds. It is what makes claws, scales, beaks and feathers strong and tough.
In the case of feathers, beta-keratin also ensures flexibility and elasticity.
Its presence may be one component of human inheritance from Neanderthals that changed African-type hair from being curly and brittle to being straight, homogeneous and resilient.
So, what are the advantages of African-type hair?
It seems likely that the genes for Neanderthal-type hair (straight and flexible) were retained by non-African Homo sapiens in order to provide good insulation for the head and neck under cold conditions.
The hair, with its added layer of beta keratin just below the cuticle, tends to be more homogeneous and tough. Hence it can grow longer and it also tends to lie flat.
On the other hand, African-type hair fibres have curls on a millimetre scale due to their non-homogeneous diameter.
This kinkiness causes the hair to mat and stand away from the scalp to allow good ventilation.
The other important characteristic of African-type hair is that it has a relatively low wettability. This means it will not collapse onto the scalp and reduce air flow as it becomes soft.
And, yet another advantage is the fact that African hair is quite brittle, causing it to break off before it grows too long (something like a built-in hairdresser!). This property would also serve to maintain an optimal cover for the head against damaging UV radiation in tropical and sub-tropical regions.
The curliness and brittleness of their hair is sometimes the bane of African and African-American women who are so pressured to look like Caucasian models.
And yet, shouldn't they be the envy of everyone who lives in the warm temperate countries of the world?