Welcome by CARTA Co-Director, Katerina Semendeferi. Opening remarks by Event Co-chair, Alysson Muotri.
The Idea Organ
Friday, February 27, 2026Abstracts
Abstracts
Paleoneurologists study the size, shape, and surfaces of the brains of human ancestors by producing casts of the interiors of their fossilized skulls (endocasts) and measuring the volumes of their braincases (cranial capacities). Cranial capacities from dated skulls show that brain size more than tripled in hominins during the Stone Age that began around 3.5 million years ago (ma). Endocasts replicate brain shape and, with luck, reproduce impressions of blood vessels and convolutions that were stamped on the inner walls of the braincase during life. However, the sulci that delimit convolutions often appear fragmentary and difficult to “read” on endocasts. Sulcal patterns differ noticeably in only two parts of the brains of great apes and humans –the lateral prefrontal cortex in the frontal lobes and the parieto-occipital association cortices located near the back of the brain. With respect to the latter, scholars have long debated whether a sulcus that approximates the anterior border of primary visual cortex in living monkeys and apes (the lunate sulcus) also did so in the brains of evolving hominins. This controversy has recently been addressed by considering what may have occurred underneath the surfaces of hominins’ evolving brains.
Because very few putative fossil hominins have been identified during the time between the origin of hominins, perhaps as early as 7.0 ma, and the beginning of the Stone Age, little is known about the size and morphology of hominin brains during approximately the first half of their evolution. However, brain evolution can still be studied during this period (the Botanic Age) by applying a variety of methods including comparative primatology and evolutionary developmental biology (evo-devo) that take into account not only brain development but also the evolution of locomotion including bipedalism. Such an extended paleoneurological synthesis (EPS) is applied here with special attention to the emergence of two related cognitive abilities that distinguish humans from other extant primates –the ability to sustain keeping a beat to an external auditory rhythm (auditory entrainment) and complex grammatical language that facilitates the expression of an open-ended number of ideas.
How do genes drive the development of cell types that build the human brain and give rise to cognition? More specifically, how does human cognitive behavior emerge from a set of evolutionarily adapted genomic programs? The human brain is comprised of heterogenous cell types and understanding the gene expression patterns and chromatin states within each of these cell types can provide important insights into both brain evolution as well as the development of cognitive disorders. We have used single cell genomics to compare human and nonhuman primate brains to uncover human brain innovations including changes in the proportions of immature oligodendrocytes in the neocortex. We have recapitulated this result in vitro using stem cell derived models from humans and nonhuman primates. Together, these data highlight the complex intersection of cellular genomics with brain evolution and function.
Humans excel at transmitting ideas, skills, and knowledge across generations, and at building on those competencies in a cumulative manner. 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.
The evolution of the human brain reflects the interplay between genetic innovation and environmental pressures. Neuro-oncological ventral antigen 1 (NOVA1) is an evolutionarily conserved splicing regulator essential for neural development and harbors a protein-coding substitution unique to modern humans compared with Neanderthals and Denisovans. To investigate the functional consequences of this human-specific change, we reintroduced the archaic NOVA1 allele into human induced pluripotent stem cells and examined neural development using cortical organoids. Organoids expressing the archaic variant exhibited accelerated maturation, increased surface complexity, altered synaptic marker expression, and changes in electrophysiological properties, indicating that the extinct human NOVA1 allele contributes to accelerated and distinct cortical development. To explore potential evolutionary pressures underlying the selection of the modern allele, we assessed long-term environmental exposure to lead using fossilized teeth from multiple hominid species spanning over two million years. Our analysis reveals pervasive lead exposure across extinct and extant hominids, challenging the notion that lead toxicity is exclusively a modern phenomenon. Notably, lead exposure selectively disrupted FOXP2 expression in cortical and thalamic organoids carrying the archaic NOVA1 variant, implicating a gene critical for speech and language development. These findings were independently validated in NOVA1 humanized mouse models with altered vocalization. Together, these fossil, cellular, and molecular findings suggest that gene–environment interactions involving NOVA1 and environmental neurotoxins may have influenced neural circuit development, social behavior, and complex language capacity, potentially conferring a selective advantage to modern humans during evolution.
My grandparents witnessed massive technology changes in energy and transportation, from steam to nuclear power, and horse and buggy to lunar rovers. My generation experienced the rise of networking and information technology. The generation to come is poised to encounter human transformation. The visions that many of us touted in the early days of ubiquitous/pervasive computing have largely come to pass in this age of IoT, and now sensors and interfaces of all kinds are embedded in smart devices across our environments that draw very little power and connect seamlessly to widespread networking infrastructure. Where do we go next? The crux of much of this will be in how this information connects to people, and how our perception, cognition, and identity effectively expand beyond our corporeal confines. Illustrated by the above speculations, this talk will explore the augmented human as viewed through the lens of recent projects happening in my Responsive Environments research group that involve sensing at various scales in the physical world (wearables, smart buildings, connected landscapes, and space missions) and how this information connects to people in different ways. Examples will include viewing 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.
Question and answer session with all speakers. Wrap-Up by symposium co-chair, Genevieve Konopka. Closing remarks by CARTA Executive Co-Director, Pascal Gagneux.
