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Humans live in a world of ideas—born in the brain, shared through language, accumulated in culture across generations, and made reality. From the first flaked stone tools to the building of shelters, from figurative and symbolic art to abstract thought, our brains are engines of imagination—an “idea organ” that has transformed both our species and the planet itself. The distinct biology of the human brain, scaffolded by language and culture, allows ideas to be formed, named, shared, and accumulated across generations. This process of cumulative culture, knowledge built upon knowledge, has propelled humans far beyond the cognitive landscapes of other large-brained animals, including our closest living and extinct relatives. This symposium explores how the human brain develops, functions, and maintains its role as the seat of ideas. We trace its story from molecules, cells, neuronal migration and circuitry, to the maternal, parental, and social influences that shape its growth, including the countless ways that brain function can be compromised at any stage of life. We examine how the uniquely human interplay of biology and culture gave rise to a brain capable of perceiving and remaking the world around us. By examining the evolutionary roots of our “idea organ,” we aim to illuminate how this singular capacity emerged—and how it continues to drive human innovation. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Science] [Show ID: 41359]

The extraordinary abilities of the cerebral cortex are central to what sets humans apart from other species. A defining feature of the cortex is its organization along a sensorimotor-to-association (S–A) axis, extending from primary sensorimotor areas to transmodal association regions that support abstract cognition. This axis varies across species and has been profoundly remodeled in humans. Nenad Sestan, professor of neuroscience at Yale, discusses his recent work on the molecular and cellular mechanisms that govern the development and evolution of the cortical S–A axis, with particular emphasis on the prefrontal cortex and its broader distributed transmodal association networks as well as their evolutionary expansion, functional roles, and vulnerability in neurological and psychiatric disorders. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Science] [Show ID: 41361]

Human brain expansion is often discussed in terms of the genetic and molecular innovations that drove uniquely human cognitive abilities. Yet evolution is fundamentally a process of tradeoffs. Disproportionate expansion of forebrain structures increases the demands placed on long-range connectivity, metabolism, and cellular maintenance, imposing costs that scale with brain size. Alex Pollen, associate professor of neurology at UC San Francisco, discusses using stem-cell-derived brain organoids to investigate the development of human-specific connectivity differences in dopaminergic neurons and to test whether these cells deploy compensatory mechanisms to cope with the metabolic and structural demands of large brains. His research findings support a model in which human brain evolution involves not only mechanisms driving greater computational capacity, but also the emergence of cellular adaptations that mitigate the costs of large, highly connected brains. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Science] [Show ID: 41357]

Dr. Bruce Miller, director of the UCSF Edward and Pearl Fein Memory and Aging Center, examines what neurodegenerative disease reveals about the neural basis of creativity and the social mind. Research in frontotemporal dementia (FTD) shows that visual creativity is not rare: a subset of patients—particularly those with left anterior temporal degeneration—develop new or intensified artistic abilities early in the disease course. These findings suggest that damage to language-dominant left hemisphere regions may release posterior visual networks from inhibition, leading to enhanced visual–spatial expression. Miller situates these observations within human evolution, proposing that art emerges with Homo sapiens, possibly linked to changes in the parietal lobe and the development of the social brain. In contrast, behavioral variant FTD erodes empathy and altruism through right frontal degeneration. Together, these patterns suggest brain asymmetry is central to our creative and social capacities. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Science] [Show ID: 41356]

From stone tools and shelters to symbolic art and abstract thought, human history is shaped by a brain built to form and share ideas. Joseph Paradiso, Professor in Media Arts and Sciences at the MIT Media Lab, explores what comes next after the early visions of ubiquitous computing have largely arrived in today’s Internet of Things world, where low-power sensors and interfaces are embedded in smart devices across our environments and connect seamlessly to widespread networking infrastructure. He asks how this information connects to people, and how perception, cognition, and identity might expand beyond our corporeal confines. Drawing on recent projects from his Responsive Environments research group, he examines sensing at multiple scales in the physical world, including wearables, smart buildings, connected landscapes, and space missions, and the different ways sensed or inferred information can connect to people. Examples include smart buildings as “prosthetic” extensions of their inhabitants, manifesting sensed or inferred phenomena in virtual analog environments, and interfaces modulated by user attention and focus or augmented by real-time AI. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Science] [Show ID: 41327]

A fundamental question in biology is: how did humans acquire their unique characteristics? What allows us to stand upright, while our primate ancestors walked on all fours? What brain alterations drove our increased intelligence and allowed us to perceive our own mortality? One of the mechanisms that has been hypothesized to be involved is changes in gene expression elicited by nucleotide alterations in non-coding regions of the human genome. Miles Wilkinson, a professor in the Department of Obstetrics, Gynecology, and Reproductive Sciences at UC, San Diego, discusses a class of DNA sequences hypothesized to have this role. These human accelerated regions (HARs) are segments of DNA that exhibit 3 characteristics that—together—make them prime candidates for specifying human-specific traits by altering patterns of gene expression. First, HARs have rapidly changed in sequence specifically in the human lineage. Second, HARs are highly conserved in sequence, indicating they that must have been selected for the ability to confer one or more function in higher organisms. Third, the vast majority of HARs are in the non-coding portion of animal genomes, indicating that most are likely to have a regulatory function. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Science] [Show ID: 41300]

Humans excel at transmitting ideas, skills, and knowledge across generations, and at building on those competencies in a cumulative manner. James Rilling, Professor of Psychology at Emory University, explores how the transmission of our cumulative culture is assumed to depend on both language and mental perspective-taking, or theory of mind. If humans have specialized abilities in these domains, we must have neurobiological specializations to support them. Our research has used comparative primate neuroimaging to attempt to identify such specializations. The arcuate fasciculus is a white matter fiber tract that links Wernicke’s and Broca’s language areas. It is known to be involved in multiple, high level linguistic functions such as lexical semantics, complex syntax, and speech fluency. Using diffusion weighted imaging and tractography, we have demonstrated human specializations in the size and trajectory of the arcuate fasciculus that may partially explain human linguistic abilities. Theory of Mind depends on a set of cortical regions that belong to a neural network known as the default mode network that is functionally connected, highly active at rest, and deactivated by attention-demanding cognitive tasks. We and others have used functional neuroimaging to show that chimpanzees and other primates appear to have a default mode network that is similar to that of humans. However, the non-human primate default mode network seems to have weaker connectivity between certain key nodes, suggesting that these connections could play a role in human theory of mind specializations. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Science] [Show ID: 41329]

Closing remarks for CARTA’s Evolutionary Origins of Art and Aesthetics symposium held in March 2009. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Show ID: 16440]

The distinct biology of the human brain, scaffolded by language and culture, allows ideas to be formed, named, shared, and accumulated across generations. Dean Falk, Professor of Anthropology, Florida State University, explains how paleoneurologists study the brains of human ancestors by producing endocasts from fossilized skulls and measuring cranial capacities. Dated skulls indicate brain size more than tripled in hominins during the Stone Age that began around 3.5 million years ago, while endocasts can also preserve traces of blood vessels and convolutions, even though sulci are often fragmentary and difficult to interpret. Falk describes how sulcal patterns differ most noticeably between great apes and humans in the lateral prefrontal cortex and in the parieto-occipital association cortices, and she addresses long-running debate about whether the lunate sulcus in evolving hominins marked the anterior border of primary visual cortex as it does in living monkeys and apes. Because few fossils exist from the earlier “Botanic Age,” she outlines how comparative primatology and evolutionary developmental biology can extend the study of brain evolution by considering brain development and locomotion, including bipedalism. She applies this extended paleoneurological synthesis with special attention to auditory entrainment and complex grammatical language. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Science] [Show ID: 41328]

Our brains are engines of imagination—an “idea organ” that has transformed both our species and the planet. Genevieve Konopka, Chair of the Department of Neurobiology in the David Geffen School of Medicine at UCLA, asks how genes drive the development of the cell types that build the human brain and give rise to cognition, and how cognitive behavior emerges from evolutionarily adapted genomic programs. Because the human brain is comprised of heterogenous cell types, she examines gene expression patterns and chromatin states within specific cell types to gain insights into brain evolution and the development of cognitive disorders. Using single cell genomics to compare human and nonhuman primate brains, her work uncovers human brain innovations, including changes in the proportions of immature oligodendrocytes in the neocortex. She recapitulates this result in vitro using stem cell derived models from humans and nonhuman primates, highlighting the intersection of cellular genomics with brain evolution and function. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Science] [Show ID: 41298]