How did blonde hair and blue eyes evolve?

Question

How did blonde hair and blue eyes evolve?

Answer 1

blonde hair results from a lack in melanin..

i'm guessing people subject to less sunlight developed less melanin (due to more melatonin secretion - the latter being a hormone secreted by the pineal gland that inhibits melanin formation)... but this is just a guess of mine.

as for blue eyes: blue eyes only began existing 10,000 years ago (before that, everyone had brown eyes). All blue eyed people have the same ancestor who had a mutation that allowed his iris to have less melanin and hence appear a clearer colour. there is no adaptive and hence evolutionary role involved with blue eyes  - it simply results from a mutation and hence remains recessive.

just found this as well:

Based on recent genetic information carried out at three Japanese universities, the date of the genetic mutation that resulted in blond hair in Europe has been isolated to about 11,000 years ago during the last Ice Age. Before then, Europeans mostly had darker hair and eyes, which is predominant in the rest of the world.[3]

There is no consensus, but many theories, as to why certain populations in Europe had a high incidences of blond hair. Some say that if the changes had occurred by natural selection, they would have taken about 850,000 years, but modern humans, emigrating from Africa, reached Europe only 35,000-40,000 years ago.[3]

Other theories suggest a different form of selection: that early men simply found blond hair more attractive.[4] Canadian anthropologist Peter Frost, under the aegis of University of St Andrews, published a study in March 2006 in the journal Evolution and Human Behavior that says blond hair evolved very quickly at the end of the last Ice Age by means of sexual selection.[5] According to the study, the appearance of blond hair and blue eyes in some northern European women made them stand out from their rivals at a time of fierce competition for males made scarce due to long, arduous hunting trips; this hypothesis argues that women with blond hair posed an alternative that helped them mate and thus increased the number of blonds.

Answer 2

originally it would have been a minor genetic mtation, then because of the rarity the ppl with them were probably more likely to breed and viola!