Day 35 has 50 protein-coding genes, including EPAS1 (Endothelial PAS domain-containing protein 1). The EPAS1 protein is a transcription factor that turns on certain genes when oxygen levels are low.
EPAS1 has recently gained fame because it is a beautiful example of local adaptation. When searching for genetic differences between high-altitude and surrounding populations in Tibet, researchers found a whopping mismatch in versions of the EPAS1 gene. The high-altitude version of EPAS1 equips people for low-oxygen conditions. Even more surprising, the actual mutations were not acquired in Tibet, but rather introgressed from an ancient extinct hominin species, the Denisovans.
Click here to see EPAS1 on Day 35.