Question

Only 1% of the world's population has red hair. It is caused by a recessive variation in the MCR1 gene that codes for hair color. In 1–2 sentences, explain how this variation could have formed in ancestral DNA, and how it has led to red hair through viable errors.

Answer 1

A spontaneous nucleotide change (e.g., a missense or nonsense mutation) in an ancestral MC1R gene could have altered the receptor’s amino acid sequence and produced a loss‑of‑function allele. Because that change is recessive and not incompatible with survival, individuals who inherit two defective copies have reduced MC1R signaling in melanocytes, shifting pigment production toward pheomelanin (red pigment) and thus red hair, while the allele persists at low frequency by drift or regional selection.