The US Navy did an experiment in which they kept a small group of volunteers underground for quite awhile without any access to a way to know what time it was. They settled into a “day” duration of about 27 hours. Some people take this as indicating that humans aren’t native to Earth. Or that day length has changed a lot since humans’ genetics were settled on a particular day length. Neither seems all that probable to me… but I have no idea why the experiment came out that way.
The US Navy did an experiment in which they kept a small group of volunteers underground for quite awhile without any access to a way to know what time it was. They settled into a “day” duration of about 27 hours. Some people take this as indicating that humans aren’t native to Earth. Or that day length has changed a lot since humans’ genetics were settled on a particular day length. Neither seems all that probable to me… but I have no idea why the experiment came out that way.