HUMANS may have started out malaria-free then caught the disease from gorillas, an analysis of ape faeces suggests.
Malaria is one of our most devastating diseases. Apes carry related malaria-causing parasites, so biologists believed humans were already infected when they split from other great apes, 5 million years ago. Other studies suggest the parasite jumped from chimps to humans at a later date.
Now Beatrice Hahn of the University of Alabama in Birmingham says both theories are wrong, and that human malaria came from gorillas. Hahn analysed 3000 samples of ape faeces from across central Africa. She found six species of malaria parasite, all of them 10 times as genetically diverse as that which infects us. She then created an evolutionary tree for the parasite, revealing that the human parasite is a recent descendant of a gorilla parasite (Nature, vol 467, p 420).
Hahn concludes that apes likely had malaria before humans split from them, but that we didn't take the parasite with us. This may be because we lost the red blood cell molecules that the ape parasite binds to. At some point no earlier than 300,000 years ago, she says, the gorilla parasite adapted to human blood and jumped species.
**Published in "New Scientist"
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