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Autistic-spectrum conditions and psychotic-spectrum conditions (mainly schizophrenia, bipolar disorder, and major depression) represent two major suites of disorders of human cognition, affect, and behavior that involve altered development and function of the social brain. We describe evidence that a large set of phenotypic traits exhibit diametrically opposite phenotypes in autistic-spectrum versus psychotic-spectrum conditions, with a focus on schizophrenia. This suite of traits is inter-correlated, in that autism involves a general pattern of constrained overgrowth, whereas schizophrenia involves undergrowth. These disorders also (...) exhibit diametric patterns for traits related to social brain development, including aspects of gaze, agency, social cognition, local versus global processing, language, and behavior. Social cognition is thus underdeveloped in autistic-spectrum conditions and hyper-developed on the psychotic spectrum.;>We propose and evaluate a novel hypothesis that may help to explain these diametric phenotypes: that the development of these two sets of conditions is mediated in part by alterations of genomic imprinting. Evidence regarding the genetic, physiological, neurological, and psychological underpinnings of psychotic-spectrum conditions supports the hypothesis that the etiologies of these conditions involve biases towards increased relative effects from imprinted genes with maternal expression, which engender a general pattern of undergrowth. By contrast, autistic-spectrum conditions appear to involve increased relative bias towards effects of paternally expressed genes, which mediate overgrowth. This hypothesis provides a simple yet comprehensive theory, grounded in evolutionary biology and genetics, for understanding the causes and phenotypes of autistic-spectrum and psychotic-spectrum conditions. (shrink)

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I present evidence that humans have evolved convergently to social insects with regard to a large suite of social, ecological, and reproductive phenotypes. Convergences between humans and social insects include: (1) groups with genetically and environmentally defined structures; (2) extensive divisions of labor; (3) specialization of a relatively restricted set of females for reproduction, with enhanced fertility; (4) extensive extramaternal care; (5) within-group food sharing; (6) generalized diets composed of high-nutrient-density food; (7) solicitous juveniles, but high rates of infanticide; (8) (...) ecological dominance; (9) enhanced colonizing abilities; and (10) collective, cooperative decision-making. Most of these convergent phenotypic adaptations stem from reorganization of key life-history trade-offs due to behavioral, physiological, and life-historical specializations. Despite their extensive socioreproductive overlap with social insects, humans differ with regard to the central aspect of eusociality: reproductive division of labor. This difference may be underpinned by the high energetic costs of producing offspring with large brains. (shrink)

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The commentaries on our target article, reflect the multidisciplinary yet highly fragmented state of current studies of human social cognition. Progress in our understanding of the human social brain must come from studies that integrate across diverse analytic levels, using conceptual frameworks grounded in evolutionary biology.

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I describe and explain evidence regarding a key role for autism spectrum cognition in human technology; tradeoffs of autistic cognition with social skills; and a model of how cumulative technological culture evolves. This model involves positive feedback whereby increased technical complexity selects for enhanced social learning of mechanistic concepts and skills, leading to further advances in technology.

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Video games are popular and ubiquitous aspects of human culture, but their relationships to psychological and neurophysiological traits have yet to be analyzed in social-evolutionary frameworks. We examined the relationships of video game usage, motivations, and preferences with autistic and schizotypal traits and two aspects of neurophysiology, reaction time and targeting time. Participants completed the Autism Quotient, Schizotypal Personality Questionnaire, a Video Game Usage Questionnaire, and two neurophysiological tasks. We tested in particular the hypotheses, motivated by theory and previous work, (...) that: participants with higher autism scores would play video games more, and participants with higher schizotypy scores would play video games less; and autism and positive schizotypy would be associated with opposite patterns of video game use, preferences and motivations. Females, but not males, with higher autism scores played more video games, and exhibited evidence of relatively male-typical video game genre preferences and motivations. By contrast, positive schizotypy was associated with reduced video game use in both genders, for several measures of game use frequency. In line with previous findings, males played video game more than females did overall, preferred action video games, and exhibited faster reaction and targeting times. Females preferred Puzzle and Social Simulation games. Faster reaction and targeting times were associated with gaming motives related to skill development and building behavior. These findings show that gaming use and patterns reflect aspects of psychology, and gender, related to social cognition and imagination, as well as aspects of neurophysiology. More generally, the results suggest that video game use is notably affected by levels of autistic and schizotypal traits, and that video games may provide an evolutionarily novel medium for imaginative play in which immersive play experiences can be decoupled from social interaction. (shrink)

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