re: #41 reine.de.tout

Waaayyy back, when the ancestors of what would become today’s algae and the single cell ancestors of what would become us a day on the Earth was… much shorter.

The Earth day probably started out around 18hrs in duration, and by the time dinosaurs appeared it was 23 hours (and some minutes). Today each day is a barely shorter than exactly 24 hours.

This is due to the Moon-Earth interaction. As the moon inches (every year) away from the Earth our days will become longer. By the time the Moon reaches its destination (roughly a third farther from us than it is today) our days will probably be over 25 hours long.

So, if all living things today have a 24 hour rhythm at the cellular level then that time length isn’t hard coded into a shared (common descent) bit of DNA. Rather it suggests living cells’ metabolism is tied to the change in radiation that is sensed every day.

This makes a lot of sense if we realize that the earliest cells (that would have been away from a thermal vent) could have relied on the daily heating cycle to provide energy flow that is essential to metabolism.

A neat thing to ponder, unless one believes all species were created 6000 years ago…