And blatant it is. I could use obvious if you like.
Faster heart rate = shorter lifespan, smaller animals tend to have faster heart rates. But that is about how genes know what to build and WHEN to build it because they can count. It's still about time, in the sense that you can upset a circadian rhythmn by simply altering the daylight hour exposure - the body will then re-calibrate itself taking into account the new rates of daylight hours and night time hours - similar to the seasons of course.