CIRCLE WITH A DOT

@davidnjoku also, imagine a founder effect... An initial group of Nigerians arrive in the UK & - this is where racism comes in - Britain is its normal, welcoming self, so the Nigerians form their own community. New Africans arrive from elsewhere on the continent & look for somewhere welcoming. The Nigerian community becomes a pan-African community. A few generations later & a Nigerian-Malian has sickle cell. Apply that to any other relatively distinct group of migrants & off you go.

@davidnjoku pretty much. Sickle cell even reduces malaria effects, so there's an advantage to having it that happens to come with a lot of negatives.

The challenge with ethnicity-associated disease is that it's correlated with other things. People who all migrated from the same village & brought with them an otherwise rare condition. Or a regional genetic survival trait that becomes harmful as conditions change. Just because it is common within an ethnicity doesn't mean •everyone• is effected.

@davidnjoku clustering of genetic traits is often random, sometimes interdependent, & can be rapid. One example I was taught about "founder effects" is that cheetahs have very little genetic diversity since the species survived a recent apocalypse. Then Jews in America have a much higher genetic risk of contracting kaposi's sarcoma, an otherwise rare cancer. Or how certain west Africans are at risk to sickle cell anaemia. Less about ethnicity than that ethnicities historically didn't intermarry.

@futurebird @twizzt there was a great book I had as a kid by Gerald Durrel called The Amateur Naturalist in which he went chapter by chapter showing you how to find interesting biomes just outside your front door. Was an amazing thing for a kid to encourage exploration.