It is heartening to see that science generally works and understanding increases as one discovery leads to another and tentative conclusions from one do not stand in the way of coming to new and different conclusions. Solid and painstaking work in the field and the lab (and not like the so-called science where the grabbing of headlines or the chasing of tenure or generation of funds dominates).
Not very long ago (3rd August 2009) the BBC reported that
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” By looking at blood samples, a US team discovered all world strains of the human malaria parasite falciparum stem from a malaria parasite in chimps. They tell Proceedings of the National Academy of Sciences how the species shift probably happened 10,000 years ago when humans turned to agriculture. Although chimps were known to harbour a parasite – Plasmodium reichenowi – that is closely related to the most common of the human malaria parasites, Plasmodium falciparum, many scientists had assumed that the two had co-existed separately. But blood tests on 94 wild and captive chimpanzees in Cameroon and the Ivory Coast suggest falciparum evolved from reichenowi. Francisco Ayala, of the University of California, Irvine, and colleagues found eight new strains of reichenowi that had striking similarities to falciparum and were genetic precursors to the human disease. The leap could have happened as early as two to three million years ago, but most likely to our Neolithic ancestors as recently as 10,000 years ago”.
But further work reported by the BBC yesterday now shows that the human malaria parasite is more likely to have originated with the gorilla parasite.
Gorillas may be the source of human cerebral malaria
“Until now, it was thought that the human malaria parasite split off from a chimpanzee parasite when humans and chimpanzees last had a common ancestor. But researchers from the US, three African countries, and Europe have examined malaria parasites in great ape faeces. They found the DNA from western gorilla parasites was the most similar to human parasites.
Malaria is caused by a parasite called Plasmodium, and is carried by mosquitoes. The most common species found in Africa, Plasmodium falciparum, causes dangerous cerebral malaria. Over 800,000 people die from malaria each year in the continent. Until now, scientists had assumed that when the evolutionary tree of humans split off from that of chimpanzees – around five to seven million years ago – so had Plasmodium falciparum. This would have meant that humans and malaria co-evolved to live together. But new evidence suggests human malaria is much newer. Dr Beatrice Hahn of the University of Birmingham, Alabama, in the US, is part of a team that had been studying HIV and related infections in humans and great apes.
To study the DNA of infections in wild apes, you cannot use blood samples. So the team collected 2,700 samples of faecal material from two species of gorilla – western and eastern – and from common chimpanzees and bonobos, also known as pygmy chimpanzees”.
http://www.bbc.co.uk/news/science-environment-11393664
Tags: Chimpanzee, Gorilla, Malaria
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