The study of hominin brain evolution has focused largely on the neocortical expansion and reorganization undergone by humans as inferred fromthe endocranial fossil record. Comparisons of modern human ...brains with those of chimpanzees provide an additional line of evidence to define key neural traits that have emerged in human evolution and that underlie our unique behavioral specializations. In an attempt to identify fundamental developmental differences, we have estimated the genetic bases of brain size and cortical organization in chimpanzees and humans by studying phenotypic similarities between individuals with known kinship relationships. We show that, although heritability for brain size and cortical organization is high in chimpanzees, cerebral cortical anatomy is substantially less genetically heritable than brain size in humans, indicating greater plasticity and increased environmental influence on neurodevelopment in our species. This relaxed genetic control on cortical organization is especially marked in association areas and likely is related to underlying microstructural changes in neural circuitry. A major result of increased plasticity is that the development of neural circuits that underlie behavior is shaped by the environmental, social, and cultural context more intensively in humans than in other primate species, thus providing an anatomical basis for behavioral and cognitive evolution.
Chimpanzee Intelligence Is Heritable Hopkins, William D.; Russell, Jamie L.; Schaeffer, Jennifer
Current biology,
07/2014, Letnik:
24, Številka:
14
Journal Article
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The role that genes play in human intelligence or IQ has remained a point of significant scientific debate dating back to the time of Galton 1. It has now become increasingly clear that IQ is ...heritable in humans, but these effects can be modified by nongenetic mechanisms 2–4. In contrast to human IQ, until recently, views of learning and cognition in animals have largely been dominated by the behaviorist school of thought, originally championed by Watson 5 and Skinner 6. A large body of accumulated research now demonstrates a variety of cognitive abilities in nonhuman animals and challenges traditional behaviorist interpretations of performance 7, 8. This, in turn, has led to a renewed interest in the role that social and biological factors might play in explaining individual and phylogenetic differences in cognition 9. Specifically, aside from early attempts to selectively breed for learning skills in rodents 10–12, studies examining the role that genetic factors might play in individual variation in cognitive abilities in nonhuman animals, particularly nonhuman primates, are scarce. Here, we utilized a modified Primate Cognitive Test Battery 13 in conjunction with quantitative genetic analyses to examine whether cognitive performance is heritable in chimpanzees. We found that some but not all cognitive traits were significantly heritable in chimpanzees. We further found significant genetic correlations between different dimensions of cognitive functioning, suggesting that the genes that explain the variability of one cognitive trait might also explain that of other cognitive traits.
•Individual differences in chimpanzee cognitive performance are heritable•Cognitive traits found to be heritable show significant genetic correlations•Sex and rearing history do not significantly influence cognitive performance
Hopkins et al. assessed cognitive performance on a series of tasks measuring social and nonsocial cognition in 99 chimpanzees and found four different components of intelligence. Individual differences in overall cognitive performance were also found to be significantly heritable, suggesting a genetic basis for cognitive performance in chimpanzees.
Human language is supported by a cortical network involving Broca’s area, which comprises Brodmann Areas 44 and 45 (BA44 and BA45). While cytoarchitectonic homolog areas have been identified in ...nonhuman primates, it remains unknown how these regions evolved to support human language. Here, we use histological data and advanced cortical registration methods to precisely compare the morphology of BA44 and BA45 in humans and chimpanzees. We found a general expansion of Broca’s areas in humans, with the left BA44 enlarging the most, growing anteriorly into a region known to process syntax. Together with recent functional and receptorarchitectural studies, our findings support the conclusion that BA44 evolved from an action-related region to a bipartite system, with a posterior portion supporting action and an anterior portion supporting syntactic processes. Our findings add novel insights to the longstanding debate on the relationship between language and action, and the evolution of Broca’s area.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Historically, population-level handedness has been considered a hallmark of human evolution. Whether nonhuman primates exhibit population-level handedness remains a topic of considerable debate. This ...paper summarizes published data on handedness in great apes. Comparative analysis indicated that chimpanzees and bonobos show population-level right handedness, whereas gorillas and orangutans do not. All ape species showed evidence of population-level handedness when considering specific tasks. Familial analyses in chimpanzees indicated that offspring and maternal (but not paternal) handedness was significantly positively correlated, but this finding was contingent upon the classification criteria used to evaluate hand preference. Overall, the proportion of right handedness is lower in great apes compared with humans, and various methodological and theoretical explanations for this discrepancy are discussed.
Executive function (EF) is a complex construct that reflects multiple higher-order cognitive processes such as planning, updating, inhibiting and set-shifting. Decline in these functions is a ...hallmark of cognitive ageing in humans, and age differences and changes in EF correlate with age-related differences and changes in association cortices, particularly the prefrontal areas. Here, we review evidence for age-related decline in EF and associated neurobiological changes in prosimians, New World and Old World monkeys, apes and humans. While EF declines with age in all primate species studied, the relationship of this decline with age-related alterations in the prefrontal cortex remains unclear, owing to the scarcity of neurobiological studies focusing on the ageing brain in most primate species. In addition, the influence of sex, vascular and metabolic risk, and hormonal status has rarely been considered. We outline several methodological limitations and challenges with the goal of producing a comprehensive integration of cognitive and neurobiological data across species and elucidating how ageing shapes neurocognitive trajectories in primates with different life histories, lifespans and brain architectures. Such comparative investigations are critical for fostering translational research and understanding healthy and pathological ageing in our own species.
This article is part of the theme issue ‘Evolution of the primate ageing process’.
For humans, there appears to be a clear link between general intelligence and self-control behavior, such as sustained delay of gratification 1–9. Chimpanzees also delay gratification 10–12 and can ...be given tests of general intelligence (g) 13–15, but these two constructs have never been compared within the same sample of nonhuman animals. We presented 40 chimpanzees with the hybrid delay task (HDT) 16, 17, which measures inter-temporal choices and the capacity for sustained delay of gratification, and the primate cognitive test battery (PCTB), which measures g in chimpanzees 13–15. Importantly, none of the sub-tasks in the PCTB directly assesses self-control or other forms of behavioral inhibition. Rather, they assess areas of physical cognition (e.g., quantity discrimination) or social cognition (e.g., gaze following). In three phases of testing, we consistently found that the strongest relation was between chimpanzee g scores and efficiency in the HDT. Chimpanzee g was not most closely related to the proportion of trials the chimpanzees chose to try to wait for delayed rewards, but rather most closely related to how good they were at waiting for those rewards when they chose to do so. We also found the same strong relation between HDT efficiency and those factors in the PCTB that loaded most strongly on chimpanzee g. These results highlight that, as with humans, there is a strong relation between chimpanzees’ self-control and overall intelligence—a relation that likely reflects the role of successful inhibitory control during cognitive processing of information and intelligent decision-making.
•In humans, delay of gratification appears to be related to general intelligence•Chimpanzees completed an intelligence test and a test of delay of gratification•Intelligence scores were most closely related to delay-of-gratification efficiency•Factors that loaded most strongly on g scores were most related to delay scores
In humans, there is a consistent relation that has been reported between self-control and general intelligence. Beran and Hopkins report the same relation in chimpanzees that were given a test of delay of gratification and a battery of social and cognitive tasks that measure general intelligence.
In the primate brain, a set of areas in the ventrolateral frontal (VLF) cortex and the dorsomedial frontal (DMF) cortex appear to control vocalizations. The basic role of this network in the human ...brain and how it may have evolved to enable complex speech remain unknown. In the present functional neuroimaging study of the human brain, a multidomain protocol was utilized to investigate the roles of the various areas that comprise the VLF–DMF network in learning rule-based cognitive selections between different types of motor actions: manual, orofacial, nonspeech vocal, and speech vocal actions. Ventrolateral area 44 (a key component of the Broca’s language production region in the human brain) is involved in the cognitive selection of orofacial, as well as, speech and nonspeech vocal responses; and the midcingulate cortex is involved in the analysis of speech and nonspeech vocal feedback driving adaptation of these responses. By contrast, the cognitive selection of speech vocal information requires this former network and the additional recruitment of area 45 and the presupplementary motor area. We propose that the basic function expressed by the VLF–DMF network is to exert cognitive control of orofacial and vocal acts and, in the language dominant hemisphere of the human brain, has been adapted to serve higher speech function. These results pave the way to understand the potential changes that could have occurred in this network across primate evolution to enable speech production.
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