Why aren't humans nocturnal?
https://www.science.org/doi/10.1126/science.ady2822

https://mrclmb.ac.uk/news-events/articles/cellular-switch-explains-why-humans-arent-nocturnal/

https://www.cam.ac.uk/research/news/the-cellular-switch-that-explains-why-humans-arent-nocturnal