Arsznov Bradley M, Sakai Sharleen T
Department of Psychology, Michigan State University, East Lansing, USA.
Brain Behav Evol. 2012;79(4):275-89. doi: 10.1159/000338670. Epub 2012 Jun 18.
The purpose of this study was to examine if differences in social life histories correspond to intraspecific variation in total or regional brain volumes in the African lion (Panthera leo) and cougar (Puma concolor). African lions live in gregarious prides usually consisting of related adult females, their dependent offspring, and a coalition of immigrant males. Upon reaching maturity, male lions enter a nomadic and often, solitary phase in their lives, whereas females are mainly philopatric and highly social throughout their lives. In contrast, the social life history does not differ between male and female cougars; both are solitary. Three-dimensional virtual endocasts were created using computed tomography from the skulls of 14 adult African lions (8 male, 6 female) and 14 cougars (7 male, 7 female). Endocranial volume and basal skull length were highly correlated in African lions (r = 0.59, p < 0.05) and in cougars (r = 0.67, p < 0.01). Analyses of total endocranial volume relative to skull length revealed no sex differences in either African lions or cougars. However, relative anterior cerebrum volume comprised primarily of frontal cortex and surface area was significantly greater in female African lions than males, while relative posterior cerebrum volume and surface area was greater in males than females. These differences were specific to the neocortex and were not found in the solitary cougar, suggesting that social life history is linked to sex-specific neocortical patterns in these species. We further hypothesize that increased frontal cortical volume in female lions is related to the need for greater inhibitory control in the presence of a dominant male aggressor.
本研究的目的是检验非洲狮（Panthera leo）和美洲狮（Puma concolor）的社会生活史差异是否与全脑或区域脑容量的种内变异相对应。非洲狮生活在群居的狮群中，通常由有亲缘关系的成年雌性、它们的后代以及一群外来雄性组成。成年后，雄性狮子进入游牧且通常独居的生活阶段，而雌性狮子一生主要留居原地且高度社会化。相比之下，美洲狮的雄性和雌性在社会生活史上并无差异，两者均为独居。使用计算机断层扫描技术，从14只成年非洲狮（8只雄性，6只雌性）和14只美洲狮（7只雄性，7只雌性）的头骨创建了三维虚拟脑模型。非洲狮（r = 0.59，p < 0.05）和美洲狮（r = 0.67，p < 0.01）的脑容量与颅底长度高度相关。相对于头骨长度的全脑容量分析显示，非洲狮和美洲狮均无性别差异。然而，主要由额叶皮质组成的相对前脑体积和表面积在雌性非洲狮中显著大于雄性，而相对后脑体积和表面积在雄性中大于雌性。这些差异特定于新皮质，在独居的美洲狮中未发现，表明社会生活史与这些物种中特定性别的新皮质模式相关。我们进一步推测，雌性狮子额叶皮质体积增加与在占主导地位的雄性攻击者面前需要更强的抑制控制有关。
