Odd Life

I have written a few times in this blog about the origins of life on Earth, as well as the search for life elsewhere in the universe. (“Unlikely Alone,” 2/28/13, “Goldilocks Globe,”1/30/11, “Extra Terrestrial Life,” 1/22/10, and “Life Out There,” 11/20/08.) When scientists talk about looking for extraterrestrial life, they often qualify their efforts as seeking for “life as we know it.” They are cautious enough to recognize that alien life-forms may not resemble ours—especially since more and more examples of extreme forms of life have been discovered right here on our little planet. Just a few decades ago science did not expect to find examples of the so-called extremophiles that we now know flourish in hot, acidic, deep oceanic, and underground locations.

A new arm of research is currently examining the possibility of life-forms here on Earth that even further stretch our current concepts of what life is. Life, “as we know it,” (so far) is carbon based, water immersed, and uses proteins made up of 20 kinds of amino acids and DNA that uses four kinds of chemical bases. We know, however, that nature contains about 100 types of amino acids and a dozen or more kinds of bases. Why does our type of life employ only a small fraction of the available chemical compounds? Could it use more? Could other forms of life use other compounds? And is carbon the only basis of life—why not silicon? Could liquids other than water be the basis of life?

These questions are increasingly being asked and explored by some scientists. They feel that it is possible that there may be other types of life living right alongside us, but we have heretofore ignored them, because our expectations of what life is have been too narrow. These scientists' explorations are being broadened to seek life forms that may be odd (to us).

This issue of alternative kinds of life is even more relevant, as we go looking for life elsewhere in the universe. In the 1970s, two NASA Viking missions to Mars were explicitly designed to test for Martian life—past or present. The Viking landers took samples, ran tests, and at first seemed to indicate they'd found life. A closer look forced NASA to declare the tests negative, however. No Mars life in those samples...or so they thought.

At the present moment the rover Curiosity is rummaging around in Mars's Gale Crater, checking to see if conditions there could once have supported life. NASA is careful to caution that this time they are not looking for life, just signs that conditions could once have been amenable for it. They've learned the lesson of getting too specific in the hunt for life.

But the newest scientific studies suggest that we may still have biochemical blinders on, when it comes to looking for life elsewhere. If there are unrecognized life forms sharing Earth with us, what even more odd forms might exist somewhere “out there?” Perhaps we should open up our minds even more.

When life first emerged on Earth—some 3.5 billion years ago—it may well have consisted of more than one chemical basis. As time passed, our type—carbon and water based—may have come to dominate. Evolution may have favored our kind of life and either eliminated the others as unfit, or relegated them to the margins, where we simply haven't noticed them. During the 150-million-year reign of the dinosaurs, mammals existed only as small critters who kept under cover and avoided the big reptiles. If you were to ask a dinosaur about mammals, he'd probably have shrugged (I believe they did have shoulders), having no clue that mammals even existed.

It's amazing what we open ourselves to when we let go of our selfish, narrow-minded viewpoints—whether the object of our attention is life forms, religion, food, or musical tastes. We have so much to learn. One of the biggest barriers to wisdom is our inability to step outside ourselves.