I will show that contrary to an existing claim, the near equality between the lifetime of the sun and the timescale for biological evolution on earth does not necessarily imply that extraterrestrial civilizations are exceedingly rare. Furthermore, I will demonstrate that a near equality between these two timescales may be the most probable relation. A calculation of the cosmic history of carbon production suggests that the most likely time for intelligent civilizations to emerge, was when the universe was already older than about ten billion years (for an assumed current age of about thirteen billion years).