As Spock Would Say?
From time to time I read about how planets in very elliptical orbits, orbits which take the planet in and out of the star's habitable zone, will probably not harbor life. Just too extreme. Of course if such a planet can support life, it would be, as that saying by Mr. Spock goes "it's life, Jim, but not as we know it." (Yes, I know that the line was not spoken by Spock in the series, but only in The Firms' song "Star Trekkin.'") But wait a minute. In pondering the report mentioned in the Creatures Frozen for 32,000 Years Still Alive post below maybe we should revisit those assumptions.
Bacteria have been found buried deep in solid rock - bacteria with very slow metabolic states and are probably thousands of years old. Penn State scientists discovered in Kalaallit Nunaat (Greenland) dormant ultra-small bacteria (Chryseobacterium greenlandensis) trapped 2 miles deep in 120,000 year old ice core samples. If Earth creatures can reanimate after being frozen for tens of thousands of years, if other Earth creatures can last for hundreds of thousands of years, or even millions, then 1) life can be possible in very elliptical orbits and 2) it still could be life as we know it. We have many example of extreme life on Earth, living under conditions scientists not long ago said were not able to support life: from deep in antarctic ice, to miles below the surface of the Earth, to boiling hot springs, to volcanic vents on the sunless depths of the ocean floor, to acidic mine drainage, to the stratosphere -- life is everywhere on this planet, and in many, many forms.
Kol-Ut-Shan, as Spock Would More Likely Say
So, is it truly implausible that life can evolve on planets that orbit in and out of the habitable zone? Evolution may possibly take longer, but the most common star, the red dwarf, develop very slowly, lasting up to hundreds of billions of years. Plenty of time for life to evolve and in its own fashion thrive. Most of the time we put a limit on where life can exist on the Earth, we later find we are wrong.
Maybe we should embrace the Star Trek Vulcan philosophy of IDIC: Infinite Diversity from Infinite Combinations (Kol-Ut-Shan according to an episode of ST: Voyager). Though if life has universal laws (like physics and chemistry, on which biology depends), I am not sure about the Infinite part. Natural laws do have some limits, boundaries, ranges. But even so, the range of diversity that can arise is still vast. Maybe it should have been ADAC: Astronomical Diversity from Astronomical Combinations. Or IDAC: Incredible Diversity from Astronomical Combinations. Of course, it is a trivial difference to be concerned over.
What matters is that there is an incredible array of life on this planet. Especially if we not only consider all the varied environments life can be found now on Earth, but all the varieties of life that have existed in all the varied Earth environments (some radically different) in the past as well. An incredible, astronomical diversity.
Coghlan, Andy. "'Resurrection Bug' Revived after 120,000 Years." Life. New Scientist. 15 June 2009. Web. 30 July 2009. <http://www.newscientist.com/article/dn17305-resurrection-bug-revived-after-120000-years.html>
Helmuth, Laura. "Top Ten Places Where Life Shouldn't Exist... But Does." Science & Nature. Smithsonian Magazine. 13 October 2009. Web. 5 September 2012. <http://www.smithsonianmag.com/science-nature/Top-Ten-Places-Where-Life-Shouldnt-Exist-But-Does.html#ixzz25e81Ip2i>
"IDIC" Memory Alpha, The Star Trek Wiki. n.d. Web. 5 September 2012. <http://en.memory-alpha.org/wiki/IDIC>
"Novel bacterial species found trapped in Greenland's ice." Penn State Live. Penn State University. 3 June 2008. Web. 30 July 2009. <http://live.psu.edu/story/31052>