12The cerebral cortex underlies our complex cognitive capabilities, yet we know little about the specific genetic loci influencing human cortical structure. To identify genetic variants, including structural variants, impacting cortical structure, we conducted a genome-wide association meta-analysis of brain MRI data from 51,662 individuals. We analysed the surface area and average thickness of the whole cortex and 34 regions with known functional specialisations. We identified 255 nominally significant loci (P ≤ 5 x 10 -8 ); 199 survived multiple testing correction (P ≤ 8.3 x 10 -10 ; 187 surface area; 12 thickness). We found significant enrichment for loci influencing total surface area within regulatory elements active during prenatal cortical development, supporting the radial unit hypothesis. Loci impacting regional surface area cluster near genes in Wnt signalling pathways, known to influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression and ADHD.One Sentence Summary: Common genetic variation is associated with inter-individual variation in the structure of the human cortex, both globally and within specific regions, and is shared with genetic risk factors for some neuropsychiatric disorders.The human cerebral cortex is the outer grey matter layer of the brain, which is implicated in multiple aspects of higher cognitive function. Its distinct folding pattern is characterised by convex (gyral) and concave (sulcal) regions. Computational brain mapping approaches use the consistent folding patterns across individual cortices to label brain regions(1). During fetal development excitatory neurons, the predominant neuronal cell-type in the cortex, are generated from neural progenitor cells in the developing germinal zone(2). The radial unit hypothesis(3) posits that the expansion of cortical surface area (SA) is driven by the proliferation of these neural progenitor cells, whereas thickness (TH) is determined by the number of neurogenic divisions. Variation in global and regional measures of cortical SA and TH are associated with neuropsychiatric disorders and psychological traits(4) ( Table S1). Twin and family-based brain imaging studies show that SA and TH measurements are highly heritable and are largely influenced by independent genetic factors(5). Despite extensive studies of genes impacting cortical structure in model organisms (6), our current understanding of genetic variation impacting human cortical size and patterning is limited to rare, highly penetrant variants (7,8). These variants often disrupt cortical development, leading to altered post-natal structure. However, little is known about how common genetic variants impact human cortical SA and TH.To address this, we conducted genome-wide association meta-analyses of cortical SA and TH measures in 51,662 individuals from 60 cohorts from around the world (Tables S2-S4). Cortical measures were extracted from structural brain MRI scan...

Research involving nonhuman primates (NHPs) has played a vital role in many of the medical and scientific advances of the past century. NHPs are used because of their similarity to humans in physiology, neuroanatomy, reproduction, development, cognition, and social complexity—yet it is these very similarities that make the use of NHPs in biomedical research a considered decision. As primate researchers, we feel an obligation and responsibility to present the facts concerning why primates are used in various areas of biomedical research. Recent decisions in the United States, including the phasing out of chimpanzees in research by the National Institutes of Health and the pending closure of the New England Primate Research Center, illustrate to us the critical importance of conveying why continued research with primates is needed. Here, we review key areas in biomedicine where primate models have been, and continue to be, essential for advancing fundamental knowledge in biomedical and biological research. Am. J. Primatol. 76:801–827, 2014. © 2014 Wiley Periodicals, Inc.

In human infancy, 2 criteria for intentional communication are (a) persistence in and (b) elaboration of communication when initial attempts to communicate fail. Twenty-nine chimpanzees (Pan troglodytes) were presented with both desirable (a banana) and undesirable food (commercial primate chow). Three conditions were administered: (a) the banana was delivered (successful communication), (b) half of the banana was delivered (partially successful communication), and (c) the chow was delivered (failed communication). The chimpanzees exhibited persistence in and elaboration of their communication in every condition except when the banana was delivered. Thus, their communication was about a specific item, demonstrating that both intentionality and nonverbal reference are capacities shared by humans with our nearest living relatives, the great apes.A significant milestone in human development is the transition to intentional communication, traditionally held to begin at about 10 to 12 months of age (e.g., Butterworth, 2001;Lock, 2001). One of the most replicated observations from studies of human communicative development is that sometime around the end of the 1st year of life, babies begin to point to distant objects (Franco & Butterworth, 1996;Leung & Rheingold, 1981). Until recently, pointing was held to be a uniquely human capacity (Donald, 1991;Povinelli & Davis, 1994;Povinelli, Bering, & Giambrone, 2003), but anecdotal reports of pointing by our nearest living relatives, the chimpanzees, have existed in the scientific literature for almost 90 years (e.g., Furness, 1916; reviewed by Leavens & Hopkins, 1999). More recently, experimental investigations have demonstrated that chimpanzees in captivity frequently point to distal objects in the absence of any explicit training (e.g., Krause & Fouts, 1997;Leavens & Hopkins, 1998Leavens, Hopkins, & Bard, 1996;Leavens, Hopkins, & Thomas, 2004).We characterize pointing by apes as a referential activity (Hopkins & Leavens, 1998;Leavens & Hopkins, 1998;Leavens et al., 1996;, meaning simply that apes and humans who use their outstretched arms and fingers to indicate distant objects or events are referring to specific entities. Because we differ in this use of the term reference from the more typical usages in developmental psycholinguistics, a brief explanatory digression is warranted. In symbolic reference, the term refers to the arbitrary nature of the relationship between an entity and the label used to signify that entity. Thus, the word big is not, in fact, bigger than the word little. For most linguists, the term reference is synonymous with symbolic reference; however, developmental psychologists interested in human communicative development have identified pointing as a class of behavior that functionally constitutes Correspondence concerning this article should be sent to David A. Leavens, Psychology Department, School of Life Sciences, University of Sussex, Falmer, East Sussex BN1 9QH. Electronic mail may be sent to davidl@sussex.ac.uk.

Hand preference for a coordinated bimanual task was assessed in a sample of 110 chimpanzees (Pan troglodytes). Subjects were presented with opaque tubes, the inside of which was coated with peanut butter. The hand and finger used to extract the peanut butter was recorded in 2 test sessions. A population right-hand bias was found. Juvenile and adolescent subjects were less lateralized than adults. All subjects primarily used their index finger to extract peanut butter. Use of the index finger was higher in adults and adolescents compared with juveniles. The results suggest that coordinated bimanual tasks (a) elicit strong hand preferences at the individual level and (b) elicit population level right-handedness.

The spontaneous index finger and other referential pointing in 3 adult, laboratory chimpanzees (Pan troglodytes) who have not received language training is reported. Of 256 total observed points, 254 were emitted in the presence of a human to objects in the environment; therefore, the points were communicative. Indicators of intentional communication used by the subjects included attention-getting behaviors, gaze alternation, and persistence until reward. Thus, pointing by these chimpanzees was intentionally communicative. These data imply that perspective-taking and referential communication are generalized hominoid traits, given appropriate eliciting contexts. Index finger pointing was more frequent with the subjects' dominant hands. This study refutes claims that indexical or referential pointing is species-unique to humans or dependent on linguistic competence or explicit training.This study was initiated when a chimpanzee began to regularly point to accidentally dropped food items outside his home cage and beyond his reach in the presence of an experimenter. We sought to determine if this pointing behavior could be defined as intentional communication, and not simple reaching, by comparing the pointing behavior of this subject and two cagemates with pointing and intentional communication in human infants.The production and comprehension of referential pointing in preverbal humans have been increasingly studied in recent decades with respect to their significance for the attribution of intentionality in preverbal children

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson’s disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder.

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Brodmann's area 44 delineates part of Broca's area within the inferior frontal gyrus of the human brain and is a critical region for speech production 1,2 , being larger in the left hemisphere than in the right 1-4 -an asymmetry that has been correlated with language dominance 2,3 . Here we show that there is a similar asymmetry in this area, also with left-hemisphere dominance, in three great ape species (Pan troglodytes, Pan paniscus and Gorilla gorilla). Our findings suggest that the neuroanatomical substrates for left-hemisphere dominance in speech production were evident at least five million years ago and are not unique to hominid evolution.To our knowledge, no one has assessed whether there is any consistent left-right anatomical asymmetry in the inferior frontal gyrus (IFG) of any non-human primate. This is surprising because it is known from cytoarchitectonic and electrical stimulation studies that many nonhuman primates, including the great apes 5,6 , possess a homologue of area 44. We have therefore investigated whether homologous neuro-anatomical asymmetries are present in area 44 in great apes.From magnetic resonance images (MRI) obtained from 20 chimpanzees (P. troglodytes), 5 bonobos (P. paniscus) and 2 gorillas (G. gorilla; Fig. 1a), we found that area 44 in these species shows a pattern of morphological asymmetry that has left-hemisphere surface-area predominance similar to the homologous cortical area of humans (mean left, 127.7 mm 2 ±8.1 s.e.; mean right, 104.2 mm 2 ±6.1 s.e.; F(1,25) = 7.45, P=0.011; see supplementary information for details of the statistical analysis, and see Fig. 1b for individual asymmetry measures). In humans, this region is part of Broca's area, a key anatomical substrate for speech functions, particularly in motor aspects of speech such as articulation and fluency 2,7 .The part possession by great apes of a homologue of Broca's area is puzzling, particularly considering the discrepancy between sophisticated human speech and the primitive vocalizations of great apes. This may be explained by the contribution that gestures have made to the evolution of human language and speech 8 . In monkeys, the so-called 'mirror neurons' in area 44 seem to subserve the imitation of hand grasping and manipulation, and this neural system may have been specialized initially for gestural and later for vocal communication 9 . In captive great apes, manual gestures are both referential and intentional 10,11 , and are preferentially produced by the right hand (which is controlled by the left hemisphere). This right-hand bias is consistently greater when gesturing is accompanied by vocalization 10 .From an evolutionary standpoint, therefore, asymmetry in area 44 may be associated with the production of gestures accompanied by vocalizations in great apes, an ability that eventually Supplementary information accompanies this communication on Nature's website (www.nature.com).