How have malaria-resistant humans adapted to the disease?
One famous adaptation is sickle-cell disease, which afflicts many people who live in malaria-prone tropical regions or whose lineage can be traced back to those locations. Sickle-cell is an interesting example because it illustrates why humans aren’t yet totally immune to malaria. There’s a trade-off: Sickle-cell is a blood disorder that, like malaria, can prove fatal, but while people who inherit the sickle-cell gene from both parents will get very sick, those who get it from just one parent tend to have fewer symptoms and have a greater chance of surviving malaria and living the longest. But these people couldn’t exist without other members of the population getting both or neither of the genes themselves. If two parents have one sickle-cell gene each, there is as great a chance of their offspring being born with just one sickle-cell gene as there is their inheriting neither or both genes.
