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Predatory patterns in wild chimpanzees are important evidence in the continuing debate about the role of hunting in the behavior of early hominids. Data are presented on the predator-prey ecology of red colobus monkeys Colobus badius tephrosceles) and chimpanzees (Pan troglodytes schweinfurthii) in Gombe National Park, Tanzania, from 1982 through 1991. During this period chimpanzees were observed to kill 429 mammalian prey items, 350 of which were red colobus. Hunts were undertaken by chimpanzees in 71.5% of encounters with red colobus, and in 52.2% of all hunts at least one colobus was caught. Hunting occurred in all months, but its frequency peaked in the late dry season months of August and September, and was lowest in the rainy months of April and May. There was greater seasonality of hunting from 1982 to 1991 than previously reported for Gombe. Hunting success varied between 40% in the rainy season and 65% in the dry season. Sixty multiple kills of colobus were reported in which from two to seven colobus were killed. Approximately 75% of all colobus caught were immatures; juveniles were the most preyed upon age class. Adult and adolescent male chimpanzees made 89.3% of all kills; the 10.7% of kills made by adult females was an increase over the 4% figure for female kills reported in the preceding decade. Hunting showed a strong "binge" tendency, with the explanation for binges likely related to social rather than ecological factors. These results are discussed in light of earlier hunting data for Gombe chimpanzees, and compared with data from other chimpanzee field studies.

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The chimpanzee life span is shorter than that of humans, which is consistent with a faster schedule of aging. We consider aspects of diet that may have selected for genes that allowed the evolution of longer human life spans with slower aging. Diet has changed remarkably during human evolution. All direct human ancestors are believed to have been largely herbivorous. Chimpanzees eat more meat than other great apes, but in captivity are sensitive to hypercholesterolemia and vascular disease. We argue that this dietary shift to increased regular consumption of fatty animal tissues in the course of hominid evolution was mediated by selection for "meat-adaptive" genes. This selection conferred resistance to disease risks associated with meat eating also increased life expectancy. One candidate gene is apolipoprotein E (apoE), with the E3 allele evolved in the genus Homo that reduces the risks for Alzheimer's and vascular disease, as well as influencing inflammation, infection, and neuronal growth. Other evolved genes mediate lipid metabolism and host defense. The timing of the evolution of apoE and other candidates for meat-adaptive genes is discussed in relation to key events in human evolution.

Turtles and tortoises (chelonians) have been integral components of global ecosystems for about 220 million years and have played important roles in human culture for at least 400,000 years. The chelonian shell is a remarkable evolutionary adaptation, facilitating success in terrestrial, freshwater and marine ecosystems. Today, more than half of the 360 living species and 482 total taxa (species and subspecies combined) are threatened with extinction. This places chelonians among the groups with the highest extinction risk of any sizeable vertebrate group. Turtle populations are declining rapidly due to habitat loss, consumption by humans for food and traditional medicines and collection for the international pet trade. Many taxa could become extinct in this century. Here, we examine survival threats to turtles and tortoises and discuss the interventions that will be needed to prevent widespread extinction in this group in coming decades.

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While field studies of wild chimpanzees have investigated the proximate determinants of hunting success, little attention has been paid to the decision to hunt. We present evidence from Gombe National Park, Tanzania, showing that the social factors that most strongly influence the decision to hunt red colobus monkeys are the presence of female chimpanzees with anogenital sexual swellings in the foraging party, the number of adult and adolescent males in the party, and the total size of the foraging party. Of these, the presence of one or more swollen females was the best predictor of a decision to undertake hunts of red colobus groups at all but the smalles chimpanzee foraging party size. Two likely explanations for this pattern are discussed. First, swollen females may be a primary influence on male grouping patterns, which in turn promotes hunting. Second, this finding, together with previous research showing that male chimpanzees preferentially give meat to estrous females, suggests that male chimpanzee hunting performance may be under sexual selection. While nutritional and ecological factors may influence chimpanzee hunting patterns at times, chimpanzees appear to hunt red colobus at least partially to obtain meat for use as a social and reproductive tool.