Source: Do Redheads Feel Less Pain?
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https://mcpress.mayoclinic.org/opioids/pain-scale/
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https://my.clevelandclinic.org/health/body/22615-melanin
https://www.ncbi.nlm.nih.gov/books/NBK459156/
https://onlinelibrary.wiley.com/doi/full/10.1111/php.12837
https://medlineplus.gov/genetics/gene/mc1r/
https://www.vetmed.ucdavis.edu/news/why-are-irish-setters-so-red
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6548228/
https://medlineplus.gov/genetics/gene/pomc/
https://link.springer.com/article/10.1007/s44254-023-00017-3
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Image Sources:
https://www.gettyimages.com/detail/video/human-brain-nervous-system-stock-footage/1482860071
https://www.gettyimages.com/detail/video/shoes-close-up-stock-footage/181842882
https://www.gettyimages.com/detail/video/girl-looking-stock-footage/1985516925