Did human hairlessness allow natural photobiomodulation 2 million years ago and enable photobiomodulation therapy today?
Present hypotheses to explain human hairlessness appear to be inadequate because hairlessness is not accompanied by any immediate benefit. A new, testable, hypothesis is advanced to explain our hairlessness based on photobiomodulation research, also known as low-level light therapy. This shows that red and near infrared radiation has a very beneficial effect on superficial tissues, including the brain. Random mutation/s resulting in complete hairlessness allowed early humans to receive daily doses of red and near infrared radiation at sunset. Photobiomodulation research shows this has a twofold effect: it results in increased mitochondrial respiratory chain activity with consequent ATP 'extrasynthesis' in all superficial tissues, including the brain. It also advantageously affects the expression of over 100 genes through the activation of transcription factor NFkB which results in cerebral metabolic and haemodynamic enhancement. It is also possible that melanin can supply electrons to the respiratory chain resulting in ATP extrasynthesis. These effects would start automatically as soon as hairlessness occurred resulting in a selective sweep of the mutation/s involved. This was followed by the very rapid brain evolution of the last 2 my which, it is suggested, was due to intelligence-led evolution based initially on the increased energy and adeptness of the newly hairless individuals. The argument is made that human hairlessness evolved approximately 2 million years ago because it made possible the conversion of sunlight wavelengths into chemical energy within our cells. By making possible the exposure of our skin to a consistent and significant source of ultraviolet radiation, the genetic mutation leading to hairlessness was positively selected for, leading to a number of downstream effects, including the accelerated growth of the energy-hungry neocortex portion of our brains.