Introduction

Human Biology and the BrainBENJAMIN CAMPBELL*

Department of Anthropology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin

Human Biology is a diverse field incorporating disci-plines such as genetics, physiology, anatomy, and anthro-pology, all with their own preoccupations and methodologi-cal constraints. If anything unites such wide-ranging inter-ests, it may be the biological implications of everydayhuman activity and its variation across individuals andpopulations. Traditionally, human biologists have meas-ured human activities in naturalistic settings. Increasingly,the measurements have included detailed physiologicaland genetic markers, substrates that can be interpreted inevolutionary terms. The principle of allocation to explaintrade-offs between the reproductive system, growth anddevelopment, and bodily maintenance has been critical tosuch interpretations, as has the use of energy as the criticalcurrency in assessing such trade-offs.On the basis of the logic of allocation, we might appor-

tion our research efforts according to the amount of timehumans spend in particular activities. The most recentAmerican Time Use Survey reports that Americans spend8.7 h each day sleeping, 4.0 hours working, 1.8 hours eat-ing and preparing food, and only 0.7 hours socializing andcommunicating. On the basis of these numbers, we mightallocate approximately one-third of our research effort tostudying sleep, a one-sixth to work, less than a one-twelfth to food and eating, and a meager 1/33 to socialactivity.Of course, such a time allocation approach is not really

practical and more importantly it is misleading. Not onlydoes it fail to take into account the different energetic costsand benefits of each activity but many human activities areactually multitasking with impact on several different bio-logical functions. Another alternative, illustrated in thisissue, is to more fully incorporate the study of the brainwithin human biology. The human brain is highly energeti-cally dependent organ, allowing for the consideration oftrade-offs between brain and body in terms of energetic cost.In addition, the human brain is the source of the multitask-ing social capacity that allows humans to sometimes bendthe simple allocation rules posited by life history theory.The articles in this issue present an up to date view of

recent research on the human brain, and its potential con-tribution to a human biology that links brain and body.John Allman’s Pearl lecture on ‘‘The Von Economo Neurons’’provides a comprehensive look at von Economo neurons(VENs) and their potential role in the importance of somaticinformation, especially that from the gut, in human socialdecision making. The article provides a compelling case forthe importance of VENs in the complex social behavior ofhuman and the great apes. Of additional interest is evi-dence that neuromedin B (NMB), a protein marker ofVENs, is present in analogous regions of the mouse brain.These results suggest that the VENs in humans and thegreat apes are not novel, but a higher level elaboration ofneural mechanisms deeply embedded in our mammalianheritage. The article by Cheryl Stimpson and colleagues,‘‘Biochemical Specificity of von Economo Neurons in homi-

noids,’’ provides more detailed results on VENs in humansand the great apes. Here the results indicate differences inthe frequency of activating transcription factor 3, interleu-kin 4 receptor (ILP4) markers between humans and thegreat apes suggesting further refinement in VENs over thecourse of hominid evolution.Other articles take a more explicitly energetic approach

to the human brain. Achim Peter’s contribution, ‘‘The Self-ish Brain: Competition for Energy Resources,’’ demon-strates how the principle of allocation can be applied tothe brain’s energy needs. His concept of ‘‘brain pull’’ issupported by clearly delineated physiological mechanismsby which the brain maintains its own energy supply. Hisconclusion that adequate ‘‘brain pull’’ may be a criticalmarker of organismal homeostasis over the life span willbe of particular interest to human biologists interested inaging and the human life span. ‘‘The Evolution of Menin-geal Vascular System in the Human Genus: from Brainshape to Thermoregulation’’ by Emiliano Bruner and col-leagues combines endocranial angiotomography in livinghumans and thermic modeling to investigate brain ther-moregulation. The finding that the middle meningeal ar-tery exhibits little blood flow in modern human adults is areal shocker. It has important implications for hominidbrain evolution, where this artery has figured promi-nently in discussions of thermoregulation. BenjaminCampbell’s article, ‘‘Adrenarche in comparative perspec-tive,’’ compares developmental trajectories of adrenal hor-mones, cortical glucose utilization, and neurodevelopmentacross rodents, primates, and humans to contextualizehuman adrenarche in evolutionary terms. The resultssuggest that postnatal increases in the adrenal hormonesDHEA and DHEAS could provide neuroprotection forslow developing brain regions to ensure the neuroplastic-ity needed to integrate the neural representation of agrowing body with emerging prefrontal function.Last but not least, Eric Vallender’s article, ‘‘Compara-

tive genetic approaches to the evolution of human brainand behavior,’’ takes a forward looking perspective on theability of genetic evidence to help unravel the mysteries ofhuman brain evolution. He notes that the on-going explo-sion of primate genomic sequencing will be a boon forunderstanding the human brain in comparative perspec-tive. At the same time, because allelic variation in genesrelated to the human brain may only provide informationback to 200,000 ybp, new forms of genetic variation willneed to be explored to fully take advantage of the geneticrevolution.

*Correspondence to: Benjamin Campbell, Department of Anthropol-ogy, University of Wisconsin-Milwaukee, Milwaukee, WI. E-mail:campbelb@uwm.edu

Received 20 October 2010; Revision received 20 October 2010;Accepted 20 October 2010

DOI 10.1002/ajhb.21138

Published online 7 December 2010 in Wiley Online Library(wileyonlinelibrary.com).

AMERICAN JOURNAL OF HUMAN BIOLOGY 23:4 (2011)

VVC 2010 Wiley-Liss, Inc.