Meeting Abstract
Bigger brains are associated with higher survival rates among species, but is greater intelligence the cause? The cognitive buffer hypothesis suggests that animals with larger brains have higher survival rates because greater cognitive abilities can help animals successfully respond to challenges in their environments. However, larger relative brain sizes are associated with numerous other traits, including lower metabolic rates (per gram), and in some cases, stronger immune defenses. The higher survival rates in large-brained species might be at least partially explained by stronger parasite defenses. Alternatively, the high energy requirements of the brain, which consumes more calories per unit mass than other organs in the body, might force a trade-off between maintaining the brain and immune function. As a result, animals with larger brains might exhibit weaker immune defenses. We investigated the relationship between immunity and relative brain size of over 100 species of terrestrial mammals. We also examined how both immunity and brain size relate to longevity. We obtained mammalian brain size data from a database of mammalian species. We assessed constitutive immune function by quantifying the ability of serum to kill four different microbes: Escherichia coli, Salmonella enterica, Candida albicans, and Micrococcus luteus. Not only will we look at how brains and immunity relate across a wide list of varying animals, we will discuss how constitutive immune varies with brain size, longevity, and body mass and examine trends between orders such as primate, carnivora, artiodactyla, and rodentia. A comparison between orders, for example carnivora and primate, may reveal how diet and lifestyle impacts immunity and brain size of species.
