MtDNA haplogroup I may improve light absorbtion and sleep & cut risk of schizophrenia
I have noticed that haplogroup I (mtDNA) is defined by a rare mutation (T10034C) in tRNA encoding Glycine. This amino acid is a known an inhibitory neurotransmitter in the central nervous system, especially in the spinal cord, brainstem, and retina. Variations in the production of glycine in the mitochondria could affect the quality of sleep and the risk of schizophrenia (both positively if production is increased).
Glycine also happens to be a biochemical precursor of porphyrins, organic compounds that strongly absorb light, which is then converted to energy and heat in the illuminated areas. Porphyrins have been used in the context of photodynamic therapy and macular degeneration.
My hypothesis is that carriers of the T10034C mutation (i.e. all members of haplogroup I) absorb light more efficiently due to an increased production of glycine and porphyrin. That would explain why haplogroup I, which apparently came to Europe with Near Eastern Neolithic farmers as N1a and developed very late (not found in any Neolithic sample so far, which are all N1a to N1a1a), seems to have undergone a positive selection in northern Europe, where light is more scarce. Haplogroup I is especially common around the Baltic, in north-west Russia and in the cloudy British Isles.
In contrast haplogroup I is completely absent from the Maghreb and places like Syria, where excessive light would have caused its carriers to develop porphyria or macular degeneration.
If confirmed this could have important implications for people of (northern) European descent living in regions with strong sunlight like the southwest of the USA, Australia, or even Spain (where lots of Britons have moved).
I have noticed that haplogroup I (mtDNA) is defined by a rare mutation (T10034C) in tRNA encoding Glycine. This amino acid is a known an inhibitory neurotransmitter in the central nervous system, especially in the spinal cord, brainstem, and retina. Variations in the production of glycine in the mitochondria could affect the quality of sleep and the risk of schizophrenia (both positively if production is increased).
Glycine also happens to be a biochemical precursor of porphyrins, organic compounds that strongly absorb light, which is then converted to energy and heat in the illuminated areas. Porphyrins have been used in the context of photodynamic therapy and macular degeneration.
My hypothesis is that carriers of the T10034C mutation (i.e. all members of haplogroup I) absorb light more efficiently due to an increased production of glycine and porphyrin. That would explain why haplogroup I, which apparently came to Europe with Near Eastern Neolithic farmers as N1a and developed very late (not found in any Neolithic sample so far, which are all N1a to N1a1a), seems to have undergone a positive selection in northern Europe, where light is more scarce. Haplogroup I is especially common around the Baltic, in north-west Russia and in the cloudy British Isles.
In contrast haplogroup I is completely absent from the Maghreb and places like Syria, where excessive light would have caused its carriers to develop porphyria or macular degeneration.
If confirmed this could have important implications for people of (northern) European descent living in regions with strong sunlight like the southwest of the USA, Australia, or even Spain (where lots of Britons have moved).