Moon not necessary for reasonable stability
Computational study reveals that even without a moon, other planets' influence would limit Earth's axial wobble to about 10 degrees.
http://news.discovery.com/space/history-of-space/earth-moon-life-tilt-110808.htm : Discovery.com story, dateline 8/8/2011.
Note also that some hypothesize that life's origins were with chemolithotrophic organisms deep underground, and the fine details of climate were probably lost on these early wee beasties.
Biting the hand that feeds IT
