2. Where did our diseases come from?

Africa: homeland of mankind and malaria

Africa is the ancestral homeland of mankind. Our species originated there perhaps 100,000 years ago. From Africa, humans spread through the Middle East and around the world. Not surprisingly, most of our original diseases evolved alongside (or inside) their human hosts in Africa, so the human race grew up in constant contact with parasites such as trypanosomes, which cause sleeping sickness, and Plasmodium, which causes malaria.

Many diseases adapted to tropical conditions were left behind by those who migrated to colder regions. In particular, many parasites that need a warm climate failed to adapt to the temperate zones. Conditions inside the human body remain fairly ...

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