10 Reasons Why Humans May Not Have Come From Earth
6. We Can't Sleep
One of Silver's arguments is that the human circadian rhythm is out of whack with the actual day-night cycle on Earth.
The circadian rhythm is the thing that regulates your sleeping and eating patterns. It means that you're tired at night and awake in the morning and is the reason why you feel jet-lagged after a long haul flight. As the Earth's day and night cycle lasts for around 24 hours (not including leap seconds because come on), it would make sense for our circadian rhythm to also be on a 24 hour cycle, but it's not.
Dr. Silver uses the argument that the human circadian rhythm is on a 25-hour cycle, meaning that it makes more sense that we should have evolved on a planet with 25 hour days. Unfortunately, Silver is wrong with the 25-hour figure, but not about the fact that it doesn't match up.
It used to be thought that our circadian rhythm was a whole hour off, turns out it's actually anything from a quarter to half an hour off. This doesn't seem like much until you realise that (providing you stuck to your natural circadian rhythm) it would only take you a month to potentially be 7 hours out of whack. That's a whole night's sleep for most people.
This means that our home planet could have been slightly bigger than Earth, in order to have longer days (although, again, it's not quite that simple), and so this also feeds into Silver's theory that our home planet had slightly higher gravity.