The origin of Plasmodium falciparum, the etiological agent of the most dangerous forms of human malaria, remains controversial. Although investigations of homologous parasites in African Apes are crucial to resolve this issue, studies have been restricted to a chimpanzee parasite related to P. falciparum, P. reichenowi, for which a single isolate was available until very recently. Using PCR amplification, we detected Plasmodium parasites in blood samples from 18 of 91 individuals of the genus Pan, including six chimpanzees (three Pan troglodytes troglodytes, three Pan t. schweinfurthii) and twelve bonobos (Pan paniscus). We obtained sequences of the parasites' mitochondrial genomes and/or from two nuclear genes from 14 samples. In addition to P. reichenowi, three other hitherto unknown lineages were found in the chimpanzees. One is related to P. vivax and two to P. falciparum that are likely to belong to distinct species. In the bonobos we found P. falciparum parasites whose mitochondrial genomes indicated that they were distinct from those present in humans, and another parasite lineage related to P. malariae. Phylogenetic analyses based on this diverse set of Plasmodium parasites in African Apes shed new light on the evolutionary history of P. falciparum. The data suggested that P. falciparum did not originate from P. reichenowi of chimpanzees (Pan troglodytes), but rather evolved in bonobos (Pan paniscus), from which it subsequently colonized humans by a host-switch. Finally, our data and that of others indicated that chimpanzees and bonobos maintain malaria parasites, to which humans are susceptible, a factor of some relevance to the renewed efforts to eradicate malaria.

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The Kibale Forest, western Uganda, is the only site where studies have compared the impact of elephants on rainforest regeneration in logged and unlogged control areas. Elephants used heavily logged areas more than lightly logged and unlogged areas. Forest gaps were used more by elephants than closed-canopy areas and large gaps more than small ones. Gaps were larger in logged than unlogged forest. There were lower densities of young trees (saplings and poles) and a higher incidence of elephant damage to them in heavily logged forest than in lightly logged and unlogged sites. Elephant use of an area and damage to young trees was inversely or unrelated to the density of young trees and directly related to the density of herbaceous tangle. Heavy logging resulted in large areas of herbaceous tangle, which attracted elephants who suppressed forest regeneration by damaging young trees and perpetuating the herbaceous tangle. The tangle directly competed with regeneration of young trees while also attracting elephants and rodents (seed and seedling predators) and facilitating increased windthrow of trees. Selective browsing of young trees by elephants affected rates of regeneration, growth form and species composition. Rather than remove elephants, a more effective and humane approach to long-term management of logging is to reduce logging offtake and incidental damage caused by timber extraction.

Following a veterinary and behavioral survey of chimpanzees from a natural population in Uganda, leaf samples of Trichilia rubescens were collected because of the unusual method of ingestion observed. The methanolic crude extract of T. rubescens leaves exhibited significant antimalarial activity in vitro. Bioassaydirected fractionation provided two new limonoids, trichirubines A and B. A greater understanding of the role of secondary compounds in the primate diet may be helpful in recovering naturally occurring compounds of medicinal significance for human medicine.Plant parts which have no apparent nutritive value and/or are rich in secondary compounds are ingested by chimpanzees (10,14,21,22). Medicinal benefits of such ingestion have been suggested (8,9,20) by the observations of two unusual behaviors proposed to control intestinal parasite infection, namely swallowing whole bristly leaves and chewing the bitter pith of Vernonia amygdalina (7,8,18,19). There is no chemical evidence to suggest a role of secondary compounds correlated with the leaf-swallowing behavior: more likely there is a mechanical effect of the surface of the whole rough hispid leaves leading to the expulsion of parasites. Instead of a physical effect, the benefit of bitter pith chewing is pharmacologically based on the activity of steroid glucosides (10,14). In order to provide new information about self-medicative behavior of chimpanzees (Pan troglodytes schweinfurthii) and the phytochemistry of the plants ingested, field studies were conducted in Kanyawara, Kibale National Park, Uganda. The survey included behavioral data collection, as well as fecal and urine analysis of samples coming from identified chimpanzees. Particular attention was focused on sick individuals and unusual or occasional feeding behaviors. We report herein the bioassaydirected fractionation of the crude extracts of the plant leaves of Trichilia rubescens and elucidation of the structure of two limonoids, namely trichirubines A and B, which possess a significant anti-Plasmodium activity.The study was conducted in the Kibale National Park (766 km 2 between 0°13 to 0°41ЈN and 30°19Ј to 30°22ЈE) in western Uganda. Data were collected between December 2000 and March 2001 (dry season) and in October 2001 (rainy season). The area contains mid-altitude moist forest, secondary forest, grassland, swamps, and plantations of Eucalyptus and pines, and it includes elements of lowland tropical rainforest, montane rainforest, and mixed deciduous rainforest. The elevation is between 800 and 1,500 m, and the rainfall averages 1,700 mm per year.The Kanyawara community of wild chimpanzees (P. troglodytes schweinfurthii), including about 50 individuals, was observed. Feeding behaviors were recorded by 10-min focal-animal sessions and ad libitum observations (1). Health state was monitored daily by noninvasive methods consisting of clinical observations, coprological study of 252 stool samples, and urinalysis of 76 samples. We focused our behavioral observations on ill chimpanzees and u...