Notable: O’Malley, R. C., Stanton, M. A., Gilby, I. C., Lonsdorf, E. V., Pusey, A., Markham, A. C., & Murray, C. M. (2016). Reproductive state and rank influence patterns of meat consumption in wild female chimpanzees (Pan troglodytes schweinfurthii). Journal of human evolution, 90, 16-28. doi:10.1016/j.jhevol.2015.09.009
Synopsis: Looking at long-term data on diet and reproductive status in wild chimpanzees at Gombe, Tanzania, O’Malley and colleagues found that pregnant females ate more meat than lactating or non-pregnant, non-lactating females. This effect was concentrated in low-ranking females, who have less access to meat than high-ranking females, so social rank and pregnancy both interact as factors influencing female meat consumption.
Interesting because: Pregnancy and lactation have high energy costs and protein costs for females. Meat is a relatively high-energy and high-protein food source. A supply of meat in the diet of pregnant or lactating females would seem to be useful or adaptive, even though meat makes up a fairly small fraction of the chimpanzee diet and can easily be dominated by high-ranking females and males. These data show that female chimpanzees do compete effectively for meat despite low social rank, when they are pregnant.
Useful insight: Females did not significantly change insect consumption, even though it is another significant source of protein and energy, more reliable than meat. They seem to be eating insects at near a maximum, limited by the high time involved in foraging insects and insect defenses. Meat has a higher degree of variability.