So my Sunday Cuteness (Afros and Flowers) post got me in the mood to talk about fros. I am seriously missing mine, thanks to my lovely Afro twists, so I am currently living vicariously through images and words that are all about the fro. Wandering through Wikipedia, I came across this interesting entry...
The evolution of Afro hair texture
During the process of going from fur to naked skin, hair texture putatively changed gradually from being straight (the condition of most mammals, including humanity's closest cousin--the chimpanzee), to Afro-like or 'kinky' (ie tightly coiled). This is made clear in a study by Iyengar[17] which has provided evidence that the roots of straight human hair may act as optic fibers that allow UV light to pass into the skin. In this sense, during the period in which pre-humans were gradually losing most of their straight body hair (fur) and thereby exposing the probably pale skin underneath their fur to the sun (Rogers et al, 2004), straight hair would have been an evolutionary liability. 'Kinks' in fiber optic tubes are known to prevent UV from passing through. Hence, tightly coiled or 'kinky' hair may have evolved to prevent the entry of UV light during the gradual process of evolution toward dark skin and the simultaneous transition from hairiness to virtual nudity. Later, when groups of modern humans migrated from Africa approximately 60,000 years ago, the straight hair phenotype, which is more common in mammals, re-emerged. (see hair texture--'The Evolution of Straight Hair'). As mentioned, the equatorial heat and higher proto-human activity levels were such that most body hair was eliminated 1-2 million years ago. However, Jablonski[16] agrees that at this time, it was evolutionarily advantageous for pre-humans (Homo erectus) to retain the hair on their heads in order to protect the skin there as they walked upright in the intense African (equatorial) UV light. Auxiliary hair in the groin and underarms was also retained; probably as a sign of sexual maturity.
Once dark skin evolved approximately 1 million years ago (Harding, 2000), Afro-hair texture was less crucial in terms of protection from UV rays. However, this texture has been sustained in some areas (such as sub-Saharan Africa) at frequencies approaching 100%. It is possible that this hair texture has the capacity to prevent UV (and possibly heat) from entering the body through the head.[citation needed] Alternatively however, it is also possible that the trait sustained high frequencies in the founding/original (sub-Saharan African) human population because most of the various genes that determined this trait retained phenotypic monomorphism in the population due to the genetotypic dominance of coiled/curled hair genes over straight hair genes.[citation needed] In other words, an ancient selective sweep likely occurred for genes coding for Afro-hair while skin was darkening 1-2 million years ago. This change has been sustained in sub-Saharan Africa, the Andamans, and Melanesia since the 200,000 year origin of humans due to high levels of isolated inter-mixture between those expressing the trait, and/or the genetic dominance of the factors determining the phenotype. Notably, sexual selection is another possible factor.[citation needed]
Also, because inter-mixture within the large sub-Saharan African population remained relatively high for a significant portion of its pre-history (compared to those who migrated outside of this region), severe, sustained isolation and its associated intensive inbreeding (i.e. bottlenecks) did not occur there (Tishkoff, 1996). Thus, straight hair did not arise by way of random mutation and isolation (i.e. genetic drift) among any of the subgroups of the sub-Saharan region. In fact, it is very likely,[citation needed] given the basically ubiquitous distribution of the Afro-hair trait among contemporary sub-Saharan Africans, that the evolution of Afro-hair predates the migration out of Africa.
Click here to read the rest.Interesting theory...what do you think???
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