How a 118-base stretch of ultraconserved DNA became HAR1, the fastest-evolving region of the human genome
iskander · x · 2026-11-06
A vivid greentext-style storytelling thread covering two classic computational biology discoveries:
- HAR1: After the chimp genome dropped in 2005, instead of hunting protein differences, researchers scanned regions conserved across mouse, rat, and chimp for 300 million years, then checked which had suddenly diverged in humans. 49 regions lit up—only 2 code for proteins. The top hit: HAR1, 118 bases, just 2 changes between chicken and chimp over 310 million years vs 18 between chimp and human over 6 million.
- From sequence to function: A wet-lab colleague in Brussels used a probe to stain embryonic brain tissue and found HAR1 expressed in Cajal-Retzius neurons at 7–9 weeks gestation—the critical window of human brain development.
- Vaults: A 1986 UCLA postdoc purifying rat liver vesicles stumbled on mysterious barrel-shaped structures, named them vaults, published with "function: unknown"—and decades later their function remains elusive.
A great narrative of how computation-first hypothesis generation leads to unexpected major biological discoveries.
More from Research
- Stanford paper proposes differentially private watermarks for LLMs — ChengleiSi · 2026-11-06
- Stanford PhD JulieKallini on testing Chomsky: can LMs learn a language no human could? — ChrisGPotts · 2026-11-06
- Exo paper: agents that rewrite their own harness at runtime, cutting model cost up to 82% — sarahcat21 · 2026-11-06
- Study: LLMs Notice Context Conflicts 73% of the Time but Tell Users 0% — rseroter · 2026-11-06
- Science's Last Exam: best of 8 frontier models scores 37.5/100, all score 0 on end-to-end research — anshulkundaje · 2026-11-06
- Tokenizer Myths and Where To Find Them: Stanford paper debunks three BPB myths — rohanpaul_ai · 2026-11-06