Scientists Discover HAR123 — The DNA “Switch” That May Help Make Human Brains Unique
Scientists have zeroed in on HAR123, a short stretch of noncoding DNA classified as a human-accelerated region (HAR). In lab and animal models, HAR123 behaves like a transcriptional enhancer—a regulatory “volume control” that fine-tunes when and how nearby genes switch on during brain development. Tinkering with this enhancer shifts neural progenitor cell dynamics and alters performance on tasks linked to cognitive flexibility, offering a rigorous, testable clue to how human brains diverged from those of our primate relatives. What Are HARs—and Why HAR123 Matters Human-accelerated regions (HARs) are tiny DNA sequences that stayed stable across mammals for tens of millions of years, then changed unusually fast on the human lineage after we split from chimpanzees. Most HARs don’t code for proteins; instead, many act as regulatory elements that modulate gene expression—crucial during development. Think of them as control dials, not blueprints. The latest breakthrough pinpoints one ...