Geneticists at a major university have identified a mutation in segments of human DNA that arose roughly a million years ago. This change is linked to cognitive differences that set early humans apart from other primates. The findings appear in a reputed science journal, underscoring a significant step in human evolution.
Some regions of the genome have remained stable through evolutionary time, yet humans show distinct alterations within these conserved zones. These differences, though embedded in regions shared with many mammals, point to a burst of change in our lineage over a relatively short span of evolution.
These regions are known as Human Accelerated Regions, or HARs. The same research team first identified HARs in the early 2000s by comparing the human genome with that of the chimpanzee. Scientists hypothesize that at least some HARs underlie traits that make humans distinct from our closest relatives, such as chimpanzees and bonobos. In the latest study, researchers highlight the three-dimensional folding of the human genome inside the cell nucleus as a critical factor during this pivotal moment in our species’ history.
To illustrate the concept, the researchers describe a long DNA strand as if it were a scarf inherited from a shared ancestor. If chimpanzees wore a version of the scarf while humans wore another, intricate patterns would not align perfectly when wrapped around the neck. In essence, the differences between human and chimpanzee DNA are structural, arising from how the genome is folded rather than from a single sequence change alone.
Many HARs function as enhancers, elements that boost the activity of nearby genes. The team aimed to determine whether structural changes influence the recruitment of these genes. To investigate, they compared the genomes of 241 mammalian species using advanced computational models. This approach led to the identification of 312 HAR-associated genes. About 30 percent of HARs were located in DNA regions where changes in folding alter the way the genome organizes itself relative to other primates.
The study also found that regions harboring HARs are rich in genes that distinguish humans from our closest relatives, chimpanzees. A substantial portion of HARs participates in embryonic development, especially in forming neural networks linked to cognitive function. As a result, these regions may contribute to characteristics that separate modern humans from our nearest kin.
Looking ahead, researchers plan to extend this work, refining models and exploring how HAR-associated changes influence developmental processes. The aim is to build a clearer picture of how genome architecture interacts with genetic regulation to shape human-specific traits and potential differences in neural development across species.