Answer:
I cant see all of them but the order is largest to smallest are Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
Explanation:
The lower you go in the hierarchy, the more closely related the living things are.
Hope I Helped Sorry
It's something to do with the fact that having sickle cell anaemia reduces the chances of contracting malaria, obviously a very common disease in Africa. I'm not quite sure what the link is but hopefully this helps a little bit?
They Increase the surface area available for the absorption of nutrients
