Creationism in Crisis
How Malaria is Evolving in Humans and Our Closest Ape Relatives
How Malaria is Evolving in Humans and Our Closest Ape Relatives
Bonobo, Pan paniscus
Photo: Sean M. Lee
Bonobo gently cradling a young mongoose
The embarrassing lack of scientific research support for Creationism continues with the publication of yet another paper that utterly refutes it and exposes the fraudulent nature of the cult's claims.
Researchers led by assistant professor Emily, E. Wroblewski of Washington University in St Louis, MO, USA, have found that the closest relative of humans, the bonobo, Pan paniscus, not only suffers from malaria parasites closely related to the that infect humans - Plasmodium falciparum - but that the pattern of immunity is related to the prevalence of infections, similar to the pattern found in humans. This shows that infections can be severe enough in bonobos to reduce fitness to survive and reproduce. Natural selection, as in humans, has led to an increase in genes for immunity in bonobo populations subject to parasitism by the organisms.
The scientists have discovered that bonobo populations differ in a key immune trait depending on the presence of malaria infection. Infected populations have a higher frequency of an immune variant that protects against developing severe disease, a pattern that mirrors what is observed among human populations.
Because of the difficulty in monitoring wild bonobos and particularly in obtaining blood samples to analyse for malaria parasites and bonobo DNA, the team used the ingenious method o c collecting fecal samples which contain both the parasite and bonobo DNA.
The research and its significance is explained in a Washington University in St Louis news release:
Endangered great apes get malaria, just like humans. New evidence from wild bonobos shows us the infection harms them, too.
Malaria is a devastating disease caused by parasites transmitted through the bites of infected mosquitos. For humans, symptoms start out mild — fever, headache and chills — but malaria infection can be fatal within 24 hours. For apes, little is known about what malaria sickness looks like, or how deadly it is.
We don’t yet have a good handle on the symptoms and mortality risk. The number of infected animals in captivity that have exhibited disease symptoms has been limited. Sometimes they show symptoms like fever and other things that might be associated with infection, and sometimes not. And in the wild these things are very difficult to track.
To us, this means that there is a selective advantage to individuals having these protective variants, because those individuals are more likely to survive their infection and reproduce, causing that variant to rise in frequency.
Seeing infected populations differ from uninfected populations in this immune trait suggests that it is because bonobos experience increased mortality or costs to their reproductive success because of their infection. The differences between the bonobo populations provides the first evidence of any kind, albeit indirect, that a wild great ape suffers any sort of consequences from their infection.
This is notable because these immune genes evolve very rapidly while trying to keep up with rapidly evolving pathogens. Because of this, it is very unusual to observe a pattern that is shared between humans and their closest living relatives.
With the numerous ways in which each host could adapt in response to their infection. I find it remarkable that both humans and bonobos respond to their infection in the same way.
Professor Emily E. Wroblewski, Lead author
Assistant professor of biological anthropology in Arts & Sciences
Department of Anthropology
Washington University in St. Louis, Saint Louis, MO, USAScientists know that malaria infection is widespread across the geographic ranges of wild chimpanzees and gorillas (they know this because researchers detect parasite DNA in the apes’ feces). In fact, the African great apes harbor at least 12 different Plasmodium species, seven of which are closely related to the human parasite that causes about 95% of human deaths.Baby bonoboNo one knows how many bonobos are left in the wild, but scientists estimate that there are between 29,500 and 50,000 individuals. Unless humans intervene in their preservation and in maintenance of their habitat, the apes could become extinct in the wild in less than a decade.Photo: Kathryn Judson
But a certain kind of ape, the bonobo, so far has escaped infection in all but two locations where researchers have studied them in the wild. Scientists can compare infected populations — where 38% of bonobos had detectable parasite DNA in their feces — to uninfected bonobos from 10 other sites across their natural range in the Democratic Republic of Congo.
This difference gives the researchers an opportunity to try to figure out some basic facts about how malaria impacts the health and mortality of great apes.
Wroblewski’s new research, published Feb. 23 in Nature Communications, finds that in areas where malaria infection has been detected, bonobos are more likely to have particular variants of an immune gene (Papa-B). The bonobo variants are very similar to a human variant (HLA-B*53) associated with protection from developing severe, and more deadly, disease. This suggests that similar immune defense mechanisms may be used in these two species.
Pattern of protection
One of Wroblewski’s collaborators on the paper, Beatrice Hahn from the University of Pennsylvania, has documented the patterns of malarial infection in the great apes over recent decades. Her previous work helped establish that the most deadly human malarial parasite got its start with a jump from gorillas.
Understanding the natural history and transmission patterns of malaria in our closest relatives is critical to gauge future transmissions.
Beatrice H. Hahn, co-author
Department of Medicine
Perelman School of Medicine
University of Pennsylvania, Philadelphia, PA, USAThis research avoided any handling or other disturbance of wild bonobos because the DNA used for sequencing was extracted from feces that were collected after they were deposited.bonobo holding her babyBonobos used to be known as the “pygmy chimpanzee” because they look very similar to, but more slender than, their chimpanzee cousins.Photo: Kathryn Judson
The scientists were particularly intrigued to observe that the immunogenetic pattern observed in infected bonobos is very similar to what is observed among human populations experiencing malaria infection in Africa.
[Professor Wroblewski] said that scientists should further investigate how this particular immune gene variant protects individuals — both bonobo and human — because understanding that mechanism might lead to an additional source of treatment or vaccination for humans.
It’s also important to understand how diseases are affecting the apes because they are endangered species. Disease is always a threat to their survival as they come under more and more pressure from human activity.
a The ranges of bonobos (Pan paniscus, yellow), western chimpanzees (Pan troglodytes verus, green), Nigeria-Cameroonian chimpanzees (P. t. ellioti, purple), central chimpanzees (P. t. troglodytes, orange), eastern chimpanzees (P. t. schweinfurthii, red), western gorillas (Gorilla gorilla, cross hatch), and eastern gorillas (Gorilla beringei, single hatch) are shown. Laverania parasites have been detected in all African ape species, except the Eastern gorilla. Range data were obtained from the IUCN Red List70,71,72,73. b The bonobo range (yellow) is shown in relation to the Congo, Lualaba, and Lomami Rivers (thick dark blue lines). Parallel lines mark the Boyoma Falls, a potential crossing point of the bonobo common ancestor24,25. Two-letter codes indicate the bonobo study sites. TL2-W bonobos are physically separated from TL2-E bonobos by the Lomami River. TL2 bonobos on both sides of the river are endemically infected with Laverania (red circles)14. One faecal sample collected at KR contained P. lomamiensis14.
For the technically minded, there is more information in the abstract to the team's published paper:
AbstractIn other words, the scientists are in no doubt whatsoever that the genetic differences between the two populations of bonobo on either side of the Lomami River, is due to the differential evolutionary selection pressure of the Laverania malaria parasite which is closely related to the Plasmodium falciparum parasite that infects humans.
The malaria parasite Plasmodium falciparum causes substantial human mortality, primarily in equatorial Africa. Enriched in affected African populations, the B*53 variant of HLA-B, a cell surface protein that presents peptide antigens to cytotoxic lymphocytes, confers protection against severe malaria. Gorilla, chimpanzee, and bonobo are humans’ closest living relatives. These African apes have HLA-B orthologs and are infected by parasites in the same subgenus (Laverania) as P. falciparum, but the consequences of these infections are unclear. Laverania parasites infect bonobos (Pan paniscus) at only one (TL2) of many sites sampled across their range. TL2 spans the Lomami River and has genetically divergent subpopulations of bonobos on each side. Papa-B, the bonobo ortholog of HLA-B, includes variants having a B*53-like (B07) peptide-binding supertype profile. Here we show that B07 Papa-B occur at high frequency in TL2 bonobos and that malaria appears to have independently selected for different B07 alleles in the two subpopulations.
Wroblewski, E.E., Guethlein, L.A., Anderson, A.G. et al.
Malaria-driven adaptation of MHC class I in wild bonobo populations. Nat Commun 14, 1033 (2023). DOI: 10.1038/s41467-023-36623-9
Copyright: © 2023 The authors.
Published by Springer Nature Ltd. Open access
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
Unsurprisingly, the bonobo populations have evolved in a similar pattern to humans subject to the same pattern of differential selection pressure by malaria. Nowhere in their paper do the scientists express the slightest doubt that the Theory of Evolution by natural selection gives anything but a complete explanation for the observable facts.
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