I read this very interesting article on physorg about how planetary tilt is essential to life and various things that can diminish axial tilt over time or not give rise to one; things that would make life less probable. But I came across this quote that I couldn't help but question the accuracy of its statement. "For an opposite case, consider Mars. Hulking Jupiter wreaks havoc with the Red Planet's obliquity, causing it to vary by perhaps as much as 60 degrees over the course of a million years, Heller said. Those disturbances lead to big swings in global temperatures and glacier cover, and on more habitable worlds that sort of climatic chaos could spell the end for life." I don't have the required mathematical and scientific knowledge to criticize [for lack of better words] this statement. Could a variance of 60 degrees over the course of a million years cause the end of life [not implying there was, of course]? Is it a constant rate of change?