The Question
Humans exhibit exceptional cognitive abilities and social skills, including complex forms of written and oral communication, our propensity to develop new technologies and explore and rapidly adapt to new ecological niches, and our ability to produce artistic representations of our imagination. These features emerged due to genetic modifications leading to known traits of brain development such as increased neocortical size and circuit complexity during human evolution and maybe to other currently unknown traits of brain development and function.
Research efforts have focused on two prominent classes of genomic innovations linked to the emergence of uniquely human traits of brain development: human accelerated regions (HARs) and human-specific gene duplications (HSGDs). HARs encode modifications to ancient gene regulatory elements that alter the level, timing and spatial patterns of gene expression in human development. HSGDs encode new proteins acting as modifiers of a range of known and unknown features of brain development and adult neuronal and circuit functions ranging from human neurogenesis to synaptic and circuit development.
The Human Brain Evolution Initiative aims to understand how human-specific genomic changes drove novel human-specific features of brain development and how these traits altered brain function and allowed the emergence of our unique cognitive abilities.
The Approach
The research team has already made significant discoveries that have provided novel insights into how HARs and HSGDs shaped human brain evolution. Their work includes developing model systems to study these genomic elements and uncovering how they influence gene regulation, brain development, and disease susceptibility in humans. Building on this knowledge, the Human Brain Evolution Initiative is now investigating four key areas:
1) Understanding how HARs and HSGDs interact to generate uniquely human brain features using combinatorial humanized mouse models.
2) Identifying and dissecting uniquely human brain features using human and nonhuman primate brain organoids and assembloids.
3) Understanding uniquely human features in neuronal development and function using xenotransplantation and ex vivo human brain tissue.
4) Understanding how human-specific genetic modifiers interact with genes implicated in human brain disorders.
Their findings will continue to provide unprecedented insights into the genetic and cellular mechanisms that influenced the evolution of the human brain and begin to reveal the events in our evolutionary history that made us human.
The Human Brain Evolution Initiative is being led by Franck Polleux at the Mortimer B. Zuckerman Mind Brain Behavior Institute at Columbia University (New York, US), James P. Noonan at Yale University (New Haven, US), and Pierre Vanderhaeghen at the VIB–KU Leuven Center for Brain and Disease Research (Leuven, Belgium).
Feature image: Catching human neurons in action: in vivo calcium imaging of human pluripotent stem cell–derived cortical pyramidal neurons transplanted in the mouse visual cortex. (Photo: Ben Vermaercke, Bonin and Vanderhaeghen Laboratories)
